Quantum-Safe Blockchain: Mapping Research Fronts in Post-Quantum Cryptography, Quantum Threat Models, and QKD Integration

Abstract

Quantum computing challenges the long-term security assumptions of blockchain systems that rely on classical public-key cryptography, motivating the adoption of post-quantum cryptography and quantum key distribution (QKD). This review maps research fronts at the intersection of blockchain and quantum-safe security, linking threat assumptions to post-quantum mechanisms, blockchain layers, and QKD positioning. Records were retrieved from Scopus and Web of Science using a two-block query and filtered through a PRISMA-guided workflow for bibliometric mapping. The final corpus comprises 648 journal articles and shows accelerated publication growth after 2023, with scientific production concentrated in a small set of leading countries. Keyword structures indicate that IoT-centric deployments dominate the semantic backbone, where authentication and intelligent methods co-occur with blockchain security primitives, while post-quantum and privacy-preserving constructs form a cohesive technical stream. QKD appears as a distinct but more specialized theme, typically discussed at the system level and shaped by infrastructure and scalability constraints. Overall, the literature is moving from conceptual risk articulation toward engineering integration; however, progress is limited by inconsistent reporting of threat models, post-quantum parameter sets, and ledger-level cost trade-offs, highlighting the need for auditable and reproducible evaluation.

1. Introduction

Blockchain systems have become a foundational substrate for decentralized coordination in settings where multiple parties require a shared, tamper-evident record without relying on a single trusted administrator [1,2,3]. Through replicated ledgers, consensus protocols, and cryptographic validation of transactions, blockchains support integrity, traceability, and auditable execution of rules, including smart contracts [3,4,5]. These properties have motivated broad adoption beyond cryptocurrencies, spanning applications such as supply chain traceability, identity management, Internet of Things ecosystems, healthcare data governance, and industrial automation [6,7,8,9]. However, blockchain security is not a single-layer problem: trust assumptions span key management and digital signatures, transaction validation and smart contract logic, consensus and network communication, and the operational realities of distributed deployments [4,7,10,11]. As a result, the security posture of blockchain-enabled systems depends on both the cryptographic primitives they instantiate and how these primitives interact with protocol design, resource constraints, and adversarial capabilities [4,5,10].

In parallel, advances in quantum information science have reshaped long-term security planning for classical cryptography [12,13]. The central concern is not that quantum computers are universally available today, but that credible progress in quantum computation challenges the longevity of widely deployed public-key systems [14]. In conventional threat models, quantum algorithms can asymmetrically undermine cryptographic hardness assumptions, motivating a transition to post-quantum cryptography and renewed interest in quantum communication approaches [14,15]. Consequently, quantum readiness has become a systems-level requirement that affects protocol design, infrastructure planning, and the lifecycle management of cryptographic dependencies, particularly in long-lived platforms where migration costs are non-trivial [13,16].

The intersection between blockchain and quantum-era security is therefore structurally important [1,5,10,15,16]. Blockchain platforms rely on cryptographic primitives for identity binding, transaction authorization, integrity assurance, and, in many designs, incentives and consensus mechanisms [1,5,10]. If the cryptographic trust layer is destabilized, the system-level consequences can propagate across ledger operation, governance, and application correctness [10,17]. Quantum-safe blockchain is thus not reducible to a single substitution step, such as replacing a classical signature with a post-quantum signature [16,17]. Instead, it is a coupled design problem that includes (i) explicit threat models and the quantum capabilities they assume, (ii) the selection and parametrization of post-quantum primitives under performance and resource constraints, (iii) compatibility with blockchain layers and deployment contexts, and (iv) the potential role of quantum key distribution and quantum networking when information-theoretic key establishment is considered [1,5,15,16,17,18].

Prior secondary studies have approached quantum-safe blockchain from complementary but partially disjoint angles, highlighting both progress and fragmentation. A first strand frames the problem primarily as a post-quantum cryptography transition challenge across blockchain and adjacent Internet of Things deployments, emphasizing standardization context, adoption constraints, and, in some cases, hybrid migration patterns that combine classical and post-quantum primitives to preserve interoperability during the transition [19]. Closely related surveys extend this perspective to networking and infrastructure by focusing on widely deployed protocol stacks, authentication infrastructures, and deployment constraints under realistic networking conditions [20,21]. A second strand consolidates cryptographic foundations and mechanism-level choices by revisiting lattice-based hardness assumptions that motivate leading candidates [22], and by cataloging post-quantum signature constructions and supporting primitives while linking algorithm choices to implementation costs and benchmarking practices relevant for system integration [21,23,24]. A third strand shifts attention to architecture-level implications in blockchain settings, including privacy-preserving designs that examine how mechanisms such as zero-knowledge proofs interact with post-quantum primitives under performance and scalability constraints [23,25], as well as domain-oriented syntheses in healthcare Internet of Medical Things contexts where resource limits and sensitive data governance foreground post-quantum privacy preservation [26]. Comparative studies also examine strategies for mitigating large key and signature footprints, for example by separating bulky artifacts from the ledger while anchoring compact commitments on-chain [27]. A fourth strand adopts a broader systems and infrastructure perspective, in which security surveys for next-generation networked environments and science mapping studies increasingly position distributed ledgers and quantum-resilient cryptography as co-evolving paradigms [28,29,30,31,32], sometimes also discussing quantum key distribution as a prospective element for future key establishment and communication security [28,29,30,31]. Finally, reviews on the maturation of quantum computing, including fault-tolerant trajectories and application-driven developments, reinforce the need to treat cryptographic readiness as a lifecycle problem rather than a one-time upgrade [33,34].

Despite this growing body of review literature, a more integrated, blockchain-centered synthesis remains limited in three respects. First, quantum threat assumptions are often treated at a generic level rather than being systematically examined across blockchain layers and trust dependencies. Second, the parametrization and system-level costs of post-quantum mechanisms are rarely analyzed together with ledger design choices and heterogeneous deployment contexts. Third, quantum key distribution and quantum networking are often addressed only peripherally, or outside a consolidated framework that links them to post-quantum migration strategies and concrete blockchain architectures. To address these limitations, this review maps the research space at the intersection of blockchain systems and quantum-era security by jointly examining three dimensions that are frequently treated in isolation: post-quantum cryptography as a transition pathway for cryptographic trust, explicit quantum threat models as the assumptions that motivate and shape that transition, and quantum key distribution integration as a distinct security direction that can reshape key-establishment and authentication architectures. In this way, the review provides a structured and transparent synthesis that clarifies how the field is framed, which technical elements are most often examined together, and where the empirical basis remains limited, fragmented, or inconsistent.

The review is therefore designed not only to document publication growth or thematic recurrence, but also to improve interpretability at both the corpus and study levels. At the corpus level, it identifies structural connections among blockchain and quantum-related security themes across countries, sources, and keyword formations. At the study level, it applies a focused qualitative synthesis to examine how the most salient contributions operationalize threat assumptions, post-quantum mechanisms, blockchain-layer effects, and QKD positioning. This combined perspective helps clarify what is currently comparable, what remains fragmented, and where the empirical foundation is still insufficient for robust system-level claims.

Accordingly, the review is guided by five research questions that define its analytical scope. First, it examines how the quantum-safe blockchain research landscape is structured and which research fronts emerge at the intersection of blockchain systems and quantum-era security considerations. Second, it investigates the quantum threat models and associated assumptions adopted in the literature, emphasizing their relation to specific blockchain layers and application contexts. Third, it identifies the post-quantum cryptographic mechanisms proposed or adopted in blockchain-related settings and evaluates whether algorithm selection and parametrization are reported with sufficient specificity to support meaningful technical comparability. Fourth, it considers contributions that include quantum key distribution, clarifying the forms of integration discussed and how quantum communication is positioned relative to post-quantum migration strategies. Fifth, it synthesizes the evaluation practices most commonly used and distills the constraints and open problems most frequently reported when quantum-safe mechanisms are introduced into blockchain-oriented architectures and deployments.

To operationalize this scope, the review pursues three objectives. First, it maps the field transparently and reproducibly, providing an evidence-based overview of how blockchain research and quantum-related security themes co-evolve in the literature. Second, it characterizes the technical content of quantum-safe proposals by linking threat assumptions to concrete cryptographic mechanisms and to the blockchain layers they affect, thereby strengthening interpretability beyond generic transition narratives. Third, it consolidates the state of quantum key distribution integration in blockchain-adjacent research by distinguishing conceptual positioning from architectural-level integration patterns and by synthesizing reported system constraints. These objectives are pursued through a bibliometric review design that combines a PRISMA-guided retrieval and filtering workflow with bibliometric mapping and a focused qualitative synthesis, thereby linking corpus-level structure with study-level technical claims within a coherent analytical narrative.

The remainder of this article is organized as follows. Section 2 describes the review design, including the reporting framework, data sources, search strategy, eligibility criteria, and analytical approach. Section 3 reports the mapped structures derived from performance indicators and thematic analyses and also synthesizes representative contributions to clarify how quantum threat models, post-quantum mechanisms, and quantum key distribution integration are treated in the literature. Section 4 interprets the mapped evidence to articulate implications for research maturity, evaluation practice, and system design priorities. Finally, Section 5 summarizes the main contributions of the review and outlines directions for future research on quantum-safe blockchain architectures and deployments.

2. Methodology

2.1. Reporting Framework and Overview

In order to enhance traceability and transparency throughout all stages of this bibliometric review, the retrieval, filtering, and corpus-construction workflow was organized in accordance with the PRISMA 2020 statement. The full corpus-construction process, including identification, filtering, and final inclusion counts, is presented in Figure 1. This review was not registered, and no review protocol was prepared.

As this study employs a bibliometric review design based on bibliographic metadata and science-mapping outputs, it does not estimate intervention effects. Consequently, study-level risk of bias assessments, effect measures, and certainty assessments were not conducted. Additionally, meta-analysis, heterogeneity modelling, sensitivity analyses, and reporting-bias assessments were not performed. The synthesis is descriptive and structural, emphasizing publication dynamics, collaboration patterns, source dissemination, and the thematic organization of the field. For clarity, the references cited in the Introduction for conceptual background and gap framing were not treated as a separately selected analytical subset. Some of them also belong to the final bibliometric corpus, but their use in the Introduction reflects contextual relevance rather than a formal salience criterion such as that applied later in Section 3.5.

2.2. Data Sources and Retrieval

Records were retrieved from Scopus and Web of Science on 9 February 2026. In Scopus, the search was executed in the TITLE-ABS-KEY field, whereas in Web of Science it was executed using TS (Topic), ensuring comparable topical coverage across databases. No initial time cutoff was applied, and the corpus therefore spans from the earliest indexed record in the two databases to the search date.

The review was intentionally restricted to journal articles in order to construct a corpus with more stable peer-review status, metadata consistency, and bibliographic comparability across sources. This decision was particularly important for the present bibliometric design, which combines performance indicators, keyword-based thematic mapping, and a focused qualitative synthesis. By limiting the analytical corpus to journal literature, we aimed to reduce heterogeneity associated with conference-driven publication cycles, variable review depth, and uneven indexing practices across databases.

2.3. Search Strategy and Query Design

The search strategy was organized into two Boolean concept blocks and executed using conjunctive logic (G1 AND G2). The design prioritized high sensitivity to map research fronts at the intersection of blockchain systems and quantum-related security threats and countermeasures. Subsequently, the specificity was ensured in two stages: (i) thematic selection and (ii) keyword cleaning and classification during thematic analysis.

No ex ante filter was imposed to privilege publications focused on implementation or experimentation. This was deliberate because the objective of the review was to map the broader research space at the intersection of blockchain systems and quantum-related security, including survey, conceptual, architectural, and implementation-oriented contributions. By the same logic, the inclusion of the term “quantum computing” in G2 was intended to preserve sensitivity for studies that articulate the risk at a strategic or systems level without necessarily using narrower post-quantum or threat-specific terminology.

2.3.1. Concept Blocks

• G1: Blockchain and ledger systems. Captures blockchain-related architectures and applications, including distributed ledgers, cryptocurrencies, smart contracts, and DeFi.
• G2: Quantum threat models and quantum-safe security. Captures quantum-era threat signals and countermeasure lines, including post-quantum and quantum-resistant framing, canonical quantum algorithms used in threat discussions, quantum computing, and QKD.

2.3.2. Operational Query

G1: (blockchain OR “distributed ledger*” OR cryptocurrency OR “smart contract*” OR DeFi)

G2: (“post-quantum” OR “quantum-safe” OR “quantum safe” OR “quantum-resistant” OR “quantum resistant” OR “quantum attack*” OR shor OR grover OR “quantum computing” OR “quantum key distribution” OR QKD)

Final query: G1 AND G2

2.4. Eligibility Criteria

Eligibility criteria were defined a priori to ensure replicability and were applied after data export and deduplication as part of the PRISMA-guided retrieval and filtering workflow presented in Figure 1.

The eligibility assessment was conducted independently by two authors after data export and deduplication, using the predefined inclusion and exclusion criteria. Disagreements regarding inclusion or exclusion were resolved through discussion until consensus was reached.

2.4.1. Inclusion Criteria

Records were included if they met all of the following conditions:

• Document type: journal articles, including items indexed as early access.
• Language: English.

2.4.2. Exclusion Criteria

Records were excluded if they met any of the following conditions:

• Language: non-English publications (Chinese, Korean, and Spanish records were excluded).
• Document type: conference papers, books and book chapters, review articles, proceeding papers, retracted items, and editorial material.

2.5. Record Management, Deduplication, and PRISMA Flow

All retrieved records were consolidated in RStudio 2025.09.1 using Bibliometrix and Biblioshiny v5.0. Records from Web of Science and Scopus were merged and deduplicated using mergeDbSources. Under this configuration, duplicates are removed deterministically from the merged collection by applying a hierarchical rule: duplicated documents are first identified via DOI when available and, otherwise, through matching on a normalized document title combined with publication year; when duplicates are detected, a single canonical record is retained.

Deduplication removed 690 records. After deduplication, 1801 records remained in the merged dataset. Language filtering removed 29 records in total (Chinese: 25, Korean: 1, Spanish: 3), yielding 1772 records for bibliometric processing. All of these records were retained in the corpus-construction workflow, and document-type filtering was then applied to define the final analytical corpus.

Eligibility filtering excluded the following document categories: conference papers (392), books and book chapters (321), reviews (250), proceeding papers (154), retracted items (4), and editorial material (3). The final analytical corpus comprised 648 records, including 629 articles and 19 with early access, as shown in Figure 1.

2.6. Bibliometric Performance Indicators and Selection of Highly Cited Contributions

The performance analysis first examined the following indicators: scientific production by year, production by country, international collaboration between countries, countries of corresponding authors, leading institutions, leading sources, and the most relevant articles. Article relevance was operationalized using TC (total citations). To support an interpretable synthesis of the field, highly cited contributions were prioritized for complete reading and focused discussion, using the thresholds TC > 100 or TC per year > 20.

2.7. Thematic Analysis Based on Author Keywords

The thematic component was conducted using Author Keywords. The analysis proceeded sequentially through: a word cloud, a keyword co-occurrence network, and a thematic map of Author Keywords. For both the co-occurrence network and the thematic map, the configuration used the Louvain clustering algorithm and the Association normalization method.

2.8. Keyword Preprocessing for Thematic Mapping

Before constructing the co-occurrence network and the thematic map, a keyword-cleaning step removed terms that tended to be generic, methodological, or overly broad anchors that obscured finer thematic structure, including several terms already present in the search query. The following terms were removed from the Author Keywords space:

blockchain, blockchains, technology, technologies, system, systems, architecture, framework, model, models, modeling, security, cryptography, quantum, post-quantum, post quantum, quantum computing, protocol, protocols, algorithm, algorithms, scheme, schemes, approach, methods, performance, evaluation, validation, testing, implementation, design, development, management, issues, future, proposals, state, communication, computing, computation, computers, computer, networks, network, servers, devices, data, information, vectors, costs, efficient/efficiency, secure, smart, artificial, internet of, na, privacy, internet, challenges, efficient, things, 0, current, article, review, reviews, surveys, literature review, systematic, systematic review, bibliometrics, bibliometric analysis, analysis, taxonomy, research, research trends, trends, intelligence, protection, optimization, signature, signatures, functions.

This preprocessing step was applied to prevent the thematic structure from being dominated by high-frequency, low-specificity descriptors and by oversized anchor terms, thereby improving interpretability in the subsequent network and thematic mapping outputs. The cleaning step was intentionally conservative, despite its broad scope. Its purpose was not to suppress important concepts, but to reduce the influence of generic anchor terms already present in the search query and likely to recur throughout the corpus. The goal was to improve thematic discrimination and reveal substructures within the mapped field, rather than to redefine the conceptual boundaries.

The next section reports the Results obtained from the performance indicators and from the thematic structures derived from Author Keywords under the configurations described above.

3. Results

3.1. Scientific Production by Year

Figure 2 summarizes the temporal evolution of scientific production by combining annual output (bars, left axis) and cumulative output (black line with markers, right axis). Annual publications increased from one article in 2017 to eight in 2018, eleven in 2019, then to twenty-five in 2020 and thirty-five in 2021. The upward trend continued in 2022 (53) and 2023 (64), followed by a marked acceleration in 2024 (131) and 2025 (263). For 2026, the figure reports 57 articles as of 9 February.

The cumulative curve confirms the concentration of output in recent years, rising from 1 article in 2017 to 197 by 2023, then to 328 in 2024 and 591 in 2025, reaching a total of 648 articles by early 2026. Because the 2026 count corresponds only to records retrieved up to 9 February 2026, it should be interpreted as a partial-year value rather than as directly comparable to complete annual totals.

The next subsection complements this temporal perspective by examining how this output is distributed across countries, thereby identifying the main geographic contributors to the field.

3.2. Geographic Distribution

3.2.1. Publications by Country

Figure 3 presents the geographic distribution of scientific production under a full counting scheme, where each country receives credit whenever it appears in the author affiliations. The map indicates a highly concentrated output in Asia, led by China (679) and India (409), followed by Saudi Arabia (143), South Korea (95), Pakistan (53), Japan (29), Malaysia (29), Bangladesh (9), Indonesia (9), Vietnam (6), Kazakhstan (6), Azerbaijan (5), and additional countries with lower frequencies, including Qatar (8), Jordan (11), Iran (16), Iraq (20), Bahrain (4), Oman (4), Israel (4), Lebanon (3), Cambodia (1), Sri Lanka (1), and Uzbekistan (3).

Beyond Asia, North America is represented by the United States (123) and Canada (27), while Europe shows a broad, multi-country footprint, including the United Kingdom (89), Italy (30), Ireland (19), Russia (19), France (18), Spain (17), Poland (16), Germany (9), Sweden (9), Portugal (8), Estonia (8), Greece (8), the Czech Republic (6), Finland (6), Romania (6), Austria (4), Denmark (4), Norway (4), Switzerland (4), Hungary (3), Slovenia (3), Turkey (3), Cyprus (2), Lithuania (2), Serbia (2), the Netherlands (1), and Croatia (1). Oceania is represented by Australia (41), New Zealand (4), Fiji (2), and Papua New Guinea (1). Africa appears through Egypt (20), Morocco (11), Tunisia (9), Nigeria (4), South Africa (4), Algeria (3), Ethiopia (3), Kenya (2), Libya (3), and Somalia (1). Latin America is also present, led by Chile (8), Brazil (7), Mexico (7), Colombia (2), and Peru (2).

Building on this country-level distribution, the next subsection examines how these geographically dispersed contributions connect through international collaboration patterns.

3.2.2. International Collaboration Network Between Countries

Figure 4 depicts the international coauthorship network at the country level. In this visualization, nodes represent countries, and edges denote coauthored publications between pairs of countries. Larger nodes indicate more prominent participation in the collaboration network, whereas thicker edges indicate stronger coauthorship ties. Colors differentiate communities in the network, thereby outlining groups of countries that collaborate more densely with each other than with the rest of the network. The structure is organized around a small set of highly visible hubs. China and India are the most prominent nodes, each connected to multiple partners across the network. India shows particularly strong ties with Saudi Arabia and Korea, and maintains additional links with several countries in Asia, Europe, and the Middle East. China also maintains strong links, including prominent ties with the United Kingdom and Pakistan, as well as additional connections with other partners.

Beyond these hubs, the community structure highlights regionally coherent and cross-regional collaboration patterns. A blue community is centered on India and Saudi Arabia. It includes Korea, Malaysia, Jordan, the United Arab Emirates, Egypt, Morocco, Ukraine, Bahrain, Indonesia, Afghanistan, Iraq, Tunisia, Vietnam, the Czech Republic, Brazil, Chile, and additional links among these nodes. China anchors a red community and includes the United Kingdom, Pakistan, Singapore, Greece, Ireland, Finland, Sweden, Denmark, Poland, Russia, Israel, and Kazakhstan, with several bridging connections extending toward other communities. A green community is organized around the United States and includes Japan, Germany, Spain, Italy, Portugal, Austria, Canada, Australia, New Zealand, Mexico, and Qatar, reflecting a broad collaboration footprint with multiple outward links. Smaller peripheral nodes, including Estonia, Azerbaijan, and Iran, as well as Romania and Georgia, appear with fewer visible connections, indicating more limited integration into the main collaboration pathways.

In order to complement these coauthorship patterns, the next subsection focuses on the countries of corresponding authors and distinguishes single-country publications and multiple-country publications to clarify leadership and internationalization profiles.

3.2.3. Corresponding Authors by Country

Table 1. Countries of corresponding authors.

Country	Publications	Publications (%)	SCP	SCP (%)	MCP	MCP (%)
China	178	27.5%	144	80.9%	34	19.1%
India	144	22.2%	102	70.8%	42	29.2%
Saudi Arabia	34	5.2%	21	61.8%	13	38.2%
Korea	33	5.1%	21	63.6%	12	36.4%
United States	27	4.2%	20	74.1%	7	25.9%
United Kingdom	21	3.2%	10	47.6%	11	52.4%
Australia	16	2.5%	15	93.8%	1	6.3%
Pakistan	13	2.0%	6	46.2%	7	53.8%
Italy	10	1.5%	9	90.0%	1	10.0%
Canada	9	1.4%	7	77.8%	2	22.2%
Iraq	9	1.4%	7	77.8%	2	22.2%
Japan	8	1.2%	4	50.0%	4	50.0%
Malaysia	7	1.1%	2	28.6%	5	71.4%
Spain	7	1.1%	4	57.1%	3	42.9%
Iran	6	0.9%	6	100.0%	0	0.0%
Poland	6	0.9%	5	83.3%	1	16.7%
Ireland	5	0.8%	2	40.0%	3	60.0%
Morocco	5	0.8 %	5	100.0%	0	0.0%
Kazakhstan	4	0.6%	3	75.0%	1	25.0%
Russia	4	0.6%	3	75.0%	1	25.0%
United Arab Emirates	4	0.6%	0	0.0%	4	100.0%
Egypt	3	0.5%	2	66.7%	1	33.3%
France	3	0.5%	2	66.7%	1	33.3%
Germany	3	0.5%	1	33.3%	2	66.7%
Indonesia	3	0.5%	2	66.7%	1	33.3%
Jordan	3	0.5%	1	33.3%	2	66.7%
Portugal	3	0.5%	3	100.0%	0	0.0%

summarizes the countries of corresponding authors and distinguishes between single-country publications (SCP) and multiple-country publications (MCP). Corresponding author output is concentrated in a limited set of countries, led by China (178; 27.5%) and India (144; 22.2%), both of which retain SCP as the dominant profile. A second tier includes Saudi Arabia, Korea, and the United States, which also remain predominantly SCP-oriented. By contrast, the United Kingdom, Pakistan, and Malaysia display comparatively stronger MCP shares, indicating a more internationalized corresponding author profile. Additional cases reflect either balanced patterns, as in Japan, or fully domestic corresponding authorship among selected lower-output countries.

Taken together, the corresponding author distribution complements the affiliation-based country profile by distinguishing broad geographic participation from corresponding author leadership and by showing that internationalization varies substantially across the main contributors. The next subsection shifts from countries to institutions, identifying the most influential organizations shaping the field.

3.3. Leading Institutional Affiliations

Table 2. Most relevant affiliations.

Affiliation(s)	Articles/Affiliation
Beihang University, Beijing University Posts and Telecommunications	38
King Saud University	24
International Institute of Information Technology	21
Xi’an University Posts and Telecommunications, Zhengzhou University of Light Industry	19
Beijing Electronic Science and Technology Institute	16
Majmaah University, University of Salerno	13
Guizhou University, North China University of Technology, School of Artificial Intelligence, Shanghai Jiao Tong University	12
Central University of Himachal Pradesh, Korea University, North China Electric Power University	11
Deakin University, Guangzhou University, The Hong Kong Polytechnic University, National Institute of Technology, Seoul National University of Science and Technology, Shenzhen University	10
Amrita School of Computing, Kyungpook National University, Manipal University Jaipur, National Institute of Technology Hamirpur, University of Oxford	9
Chongqing University Posts and Telecommunications, Ege University, King Faisal University, Kumoh National Institute of Technology, Lovely Professional University, Muroran Institute of Technology, Nanjing University of Information Science and Technology, School of Cyberspace Science and Technology, University of Sfax	8
Communication University of China, Feng Chia University, Prince Sattam bin Abdulaziz University, Qufu Normal University, SRM Institute of Science and Technology, Sun Yat-sen University, Texas A&M University, Thapar Institute of Engineering and Technology, University of Tabuk, University of Tartu, University of Warsaw, Xidian University	7

summarizes the most relevant affiliations using the Articles/Affiliation metric. The institutional profile is concentrated in a limited group of highly visible organizations, led by Beihang University and Beijing University of Posts and Telecommunications, followed by King Saud University and the International Institute of Information Technology. Beyond these leading affiliations, the table shows a broad distribution of institutions tied at intermediate production levels, indicating that the field combines a small set of prominent institutional hubs with a wider tail of contributing organizations.

Overall, this institutional pattern is consistent with the geographic concentration and cross-country connectivity reported in the preceding subsections, while also showing that scientific production is not confined to a single institutional core. The next subsection examines the most relevant sources to characterize the primary dissemination channels for this institutional output.

3.4. Most Relevant Sources

Table 3. Most relevant sources. Quartile labels are provided according to the SCImago Journal Rank (SJR) database for the 2025 reporting year.

Source(s)	Articles/Journal
IEEE Access (Q1)	44
IEEE Internet of Things Journal (Q1)	18
Scientific Reports (Q1)	17
IEEE Transactions on Consumer Electronics (Q1)	16
CMC-Computers, Materials & Continua (Q2)	15
Computers & Electrical Engineering (Q1), Quantum Information Processing (Q1)	13
Sensors (Q1)	12
Applied Sciences (Switzerland) (Q2), IEEE Transactions on Intelligent Transportation Systems (Q1)	10
Cryptography (Q2)	9
Entropy (Q2), Internet of Things (Q1), Journal of Information Security and Applications (Q1), Security and Communication Networks (Q2; discontinued)	8
Cluster Computing (Q1), Computer Networks (Q1), IEEE Transactions on Information Forensics and Security (Q1), Information Sciences (Q1), The Journal of Supercomputing (Q2)	7
IEEE Communications Surveys & Tutorials (Q1), IEEE Transactions on Dependable and Secure Computing (Q1), IEEE Transactions on Network Science and Engineering (Q1), Journal of Discrete Mathematical Sciences and Cryptography (Q3), Mathematics (Q2), SN Computer Science (Q2)	6
Concurrency and Computation: Practice & Experience (Q2), IEEE Open Journal of the Communications Society (Q1), International Journal of Advanced Computer Science and Applications (Q3), Peer-to-Peer Networking and Applications (Q2)	5

summarizes the most relevant publication venues using the Articles/Journal metric. The source distribution is concentrated in a limited set of leading outlets, with IEEE Access clearly occupying the most prominent position, followed by several high-visibility journals in engineering, Internet of Things, security, and applied computing. Beyond these leading venues, the table shows a broader second tier of sources distributed across Q1 to Q3, indicating that the field is disseminated through both high-impact multidisciplinary engineering outlets and more specialized journals in cryptography, networking, and applied systems research.

Overall, the source profile suggests that the corpus is disseminated primarily through engineering and security-oriented publication channels, with a smaller but still visible contribution from specialized cryptography and applied computing journals. Building on these dissemination patterns, the next subsection examines the most cited documents to identify the contributions that have exerted the strongest citation influence within the corpus.

3.5. Overview of the Most Salient Studies

Table 4 reports the subset of studies selected for focused qualitative synthesis. The selection was designed to capture both cumulative citation prominence and rapidly emerging influence. Specifically, we included (i) the ten highest-TC documents in the corpus and added two complementary inclusions to reduce recency bias: (ii) one recent study with a high TC/year despite a lower cumulative TC, and (iii) the most cited contribution published in the most recent year represented in the selection (2025). In this way, the subset combines high cumulative visibility with sensitivity to more recent contributions that are attracting attention at a faster rate.

The resulting set is led by [35] (2021; TC = 322; TC/year = 53.67) and [36] (2021; TC = 240; TC/year = 40.00), and it also includes early contributions explicitly centered on quantum-resilient ledger security, such as [37] (2018; TC = 180; TC/year = 20.00) and [38] (2018; TC = 117; TC/year = 13.00), together with more recent studies showing strong citation dynamics. To broaden coverage beyond cumulative citation counts, we additionally include [39] (2024; TC = 86; TC/year = 28.67) due to its elevated citation rate, and [40] (2025; TC = 21; TC/year = 10.50) as the most cited contribution from the latest year in the selection.

In the remainder of this subsection, we provide a structured synthesis of these studies covering: (i) purpose, scope, and contribution; (ii) blockchain context and affected layer; (iii) threat model and quantum threat assumptions; (iv) post-quantum mechanism and parameterization (when reported); (v) QKD integration (when applicable); (vi) results, claims, and limitations; and (vii) the gap explicitly identified by each study.

Table 4. Most salient studies.

Title	Year	TC	TC/Year	Study
Security and Privacy for 6G: A Survey on Prospective Technologies and Challenges	2021	322	53.67	[35]
The Roadmap to 6G Security and Privacy	2021	240	40.00	[36]
Metaverse for Healthcare: A Survey on Potential Applications, Challenges and Future Directions	2023	202	50.50	[41]
Quantum-secured blockchain	2018	180	20.00	[37]
Advancements in Computing: Emerging Trends in Computational Science with Next-Generation Computing	2024	180	60.00	[42]
Cybersecurity in logistics and supply chain management: An overview and future research directions	2021	121	20.17	[43]
A Secure Cryptocurrency Scheme Based on Post-Quantum Blockchain	2018	117	13.00	[38]
Applications of Distributed Ledger Technologies to the Internet of Things: A Survey	2020	116	16.57	[44]
AI-Empowered Fog/Edge Resource Management for IoT Applications: A Comprehensive Review, Research Challenges, and Future Perspectives	2024	115	38.33	[45]
Security Considerations for Internet of Things: A Survey	2020	113	16.14	[46]
Modern computing: Vision and challenges	2024	86	28.67	[39]
Integrating Post-Quantum Cryptography and Blockchain to Secure Low-Cost IoT Devices	2025	21	10.50	[40]

Table 4. Most salient studies.

Title	Year	TC	TC/Year	Study
Security and Privacy for 6G: A Survey on Prospective Technologies and Challenges	2021	322	53.67	[35]
The Roadmap to 6G Security and Privacy	2021	240	40.00	[36]
Metaverse for Healthcare: A Survey on Potential Applications, Challenges and Future Directions	2023	202	50.50	[41]
Quantum-secured blockchain	2018	180	20.00	[37]
Advancements in Computing: Emerging Trends in Computational Science with Next-Generation Computing	2024	180	60.00	[42]
Cybersecurity in logistics and supply chain management: An overview and future research directions	2021	121	20.17	[43]
A Secure Cryptocurrency Scheme Based on Post-Quantum Blockchain	2018	117	13.00	[38]
Applications of Distributed Ledger Technologies to the Internet of Things: A Survey	2020	116	16.57	[44]
AI-Empowered Fog/Edge Resource Management for IoT Applications: A Comprehensive Review, Research Challenges, and Future Perspectives	2024	115	38.33	[45]
Security Considerations for Internet of Things: A Survey	2020	113	16.14	[46]
Modern computing: Vision and challenges	2024	86	28.67	[39]
Integrating Post-Quantum Cryptography and Blockchain to Secure Low-Cost IoT Devices	2025	21	10.50	[40]

To complement the focused qualitative synthesis,

Table 5. Order-of-magnitude resource profile of representative digital-signature families relevant to quantum-safe blockchain integration.

Signature Family	Representative Scheme	Public Key Size (Bytes)	Signature Size (Bytes)	Typical Magnitude for Blockchain Integration	Expected Ledger-Level Impact	Evidence Status in the Reviewed Literature
Classical baseline	Ed25519	32	64	Byte-scale footprint; practical baseline for interpreting post-quantum overhead.	Minimal per-transaction footprint; limited pressure on block occupancy, propagation bandwidth, and long-term ledger growth.	Contextual classical benchmark included for scale comparison.
Lattice-based PQ signatures	CRYSTALS-Dilithium-5	2592	4595	Few-kilobyte public key and signature; substantially larger than classical baselines but still within a comparatively moderate post-quantum range.	Clear transaction-footprint inflation; fewer transactions per block, higher propagation overhead, and stronger storage pressure, especially in constrained IoT or long-lived blockchain deployments.	Directly reported in the implementation-oriented corpus and explicitly discussed as a scalability concern in blockchain-enabled IoT settings [40].
Stateless hash-based PQ signatures	SPHINCS+/ SLH-DSA	32–64	7856–49,856	Small public key but very large signature output; signature-dominated overhead regime.	Strongest block-space and bandwidth pressure among the representative rows; likely substantial transaction inflation and long-term ledger growth penalties in high-volume chains.	Contextual stateless-hash benchmark included for cross-family comparison; useful for interpreting trade-offs between statelessness and ledger footprint.

provides an order-of-magnitude comparison of representative digital-signature families relevant to quantum-safe blockchain integration. The purpose is to make ledger-level scalability trade-offs more interpretable by showing how signature-family choice can affect transaction footprint, block occupancy, propagation overhead, and long-term ledger growth. The reviewed corpus provides implementation-grounded size evidence explicitly for Dilithium-5, whereas the Ed25519 and SPHINCS+/SLH-DSA rows are included as contextual benchmarks for cross-family comparison. In addition, the broader literature represented in the salient corpus distinguishes stateful hash-based signatures such as XMSS and LMS from stateless designs, a difference that is operationally relevant in blockchain settings because stateful schemes require correct persistent state progression, whereas stateless alternatives avoid state-reuse risk but may impose stronger transaction-size overhead.

The study by [35] (TC = 322 and TC/year = 53.67) provides a layered survey of security and privacy for sixth-generation mobile networks by organizing the discussion across the physical, connection, and service layers. In doing so, it also derives lessons from legacy security architectures, thereby offering a consolidated view of how emerging sixth-generation technologies expand the attack surface and why corresponding defenses must evolve accordingly.

Within this framework, blockchain is discussed as a prospective enabler of decentralized trust, particularly for mutual authentication and integrity assurance among key network entities. However, the study simultaneously positions blockchain as an early-stage technology in sixth-generation settings, mainly due to scalability and resource constraints; consequently, its role is framed as predominantly service-layer oriented, with emphasis on trust functions and related assurance mechanisms.

From a threat-model perspective, the analysis considers heterogeneous adversaries operating across integrated space–air–ground environments and, in that broader context, highlights quantum computing as a strategic risk to public-key cryptography and associated protocols. These quantum assumptions follow the standard model, in which Shor’s algorithm compromises RSA and elliptic curve cryptography, thereby motivating migration strategies toward quantum-resilient alternatives.

Accordingly, post-quantum mechanisms are presented at the level of candidate classes and exemplars. These include lattice-based cryptography such as NTRU, hybrid key exchange that combines elliptic curve Diffie–Hellman over NIST P-256 with a quantum-safe key encapsulation mechanism such as Kyber512, and a hash-based combiner using SHA-256. Moreover, when quantum communication is considered, QKD is introduced as an information-theoretic source of key establishment; nevertheless, the study emphasizes practical barriers, including long-distance transmission, repeater availability, and cost.

Overall, the results are primarily taxonomic and prospective. The limitations stem from the conceptual maturity of sixth-generation security and the early operational status of the enabling technologies discussed. Consistent with this assessment, the study highlights gaps in deployable quantum-safe architectures, in standardization readiness, and in the practical integration of blockchain and quantum-safe mechanisms under strict latency and energy constraints.

Study [36] (TC = 240 and TC/year = 40.00) develops a roadmap for security and privacy in sixth-generation networks by articulating anticipated requirements, key security performance indicators, architectural components, enabling technologies, the threat landscape, and candidate mitigations. In this sense, its main contribution is the consolidation of early guidance for research and standardization at a stage when sixth-generation concepts remain fluid and therefore subject to revision.

Within that roadmap, blockchain is introduced through the lens of distributed ledger technology, particularly in relation to blockchainized sixth-generation services and smart contract automation. This discussion is situated primarily in the service and management plane, where decentralization is expected to enhance trust and auditability; nevertheless, the study also notes that these benefits may come at the cost of additional vulnerabilities that must be incorporated into the overall risk assessment.

Consistently, the threat model first enumerates classical blockchain attacks, including majority-control attacks, double-spending, and smart contract vulnerabilities such as reentrancy. It then broadens the landscape to include quantum-based attacks by assuming adversaries may exploit future quantum capabilities. In particular, the analysis underscores that discrete logarithm-based cryptography could become tractable in polynomial time under Shor’s algorithm, which in turn motivates a shift toward post-quantum keying mechanisms and, more broadly, toward stronger end-to-end security designs.

In that context, post-quantum cryptography is seen as a necessary research direction and is often discussed alongside physical-layer security. However, the study does not advance to a concrete instantiation or parameter set. Similarly, QKD is mentioned as a quantum communication protocol with potential applicability to sixth-generation links—notably in satellite and terrestrial systems—but is treated as a forward-looking option rather than an implemented component.

Overall, the results are conceptual and organizational, emphasizing requirements, challenges, and projects rather than empirical validation. Accordingly, the limitations follow from the early stage of sixth-generation design and from the absence of deployment-level evidence. In line with these constraints, the paper identifies gaps in quantifiable sixth-generation security metrics, in feasible quantum-safe security for constrained devices, and in the robust integration of distributed ledgers without undermining latency, reliability, and manageability goals.

The study by [41] (TC = 202 and TC/year = 50.50) surveys metaverse-oriented healthcare by synthesizing enabling technologies, application scenarios, related initiatives, and adoption challenges. In this way, the contribution is primarily organizational: it connects immersive interaction modalities with healthcare workflows and data governance requirements, while also outlining prospective research directions for an emerging, interdisciplinary domain.

Within this framing, blockchain is presented as an enabler of decentralization, integrity, and transparency, as well as a mechanism for managing digital assets—including non-fungible tokens and cryptocurrencies—inside metaverse environments. Consequently, the discussion situates blockchain mainly at the application and data management layer, where persistent records and identity-linked assets are handled and where traceability-oriented functionalities are expected to play a supporting role.

Regarding threats, the study focuses on general security and privacy issues in metaverse systems, emphasizing risks associated with centralized storage and, more broadly, the need for trustworthy data handling across complex socio-technical settings. However, it does not define a quantum adversary or a quantum threat model; instead, quantum computing is referenced as an enabling technology rather than as a cryptanalytic attacker. Consistent with this scope, no post-quantum cryptographic mechanisms or parameterizations are provided, and no QKD integration is proposed.

Accordingly, the results are framed in terms of potential benefits and anticipated challenges rather than verified performance. The limitations stem from the emergent character of the area, its interdisciplinary coupling, and the lack of validated deployments. In line with these constraints, the study highlights gaps in secure and interoperable healthcare metaverse architectures, in privacy-preserving data governance, and in validated designs that scale blockchain-enabled components without compromising usability or regulatory compliance.

The study by [37] (TC = 180 and TC/year = 20.00) proposes a quantum-safe blockchain platform and reports an experimental realization in which quantum key distribution supplies keys for information-theoretically secure authentication. The scope is a Byzantine fault-tolerant distributed ledger setting; accordingly, the main contribution is a concrete demonstration that a blockchain-style consensus protocol can operate without digital signatures by relying instead on authenticated broadcast supported by secret keys.

In this context, the blockchain design is a permissioned protocol that prioritizes consensus and message authentication. Therefore, the affected layer is primarily the communication and consensus layer, rather than application-level smart contract execution.

From a security standpoint, the threat model explicitly considers adversaries equipped with quantum computation. Under this assumption, classical public-key signatures become vulnerable, and quantum search can also provide mining-related advantages. In response, the study discusses mitigating the Grover-related risk by increasing the block hash length beyond the non-quantum safety conventions.

Consistent with these assumptions, the cryptographic mechanism replaces public-key signatures with message authentication based on shared keys and universal hashing, thereby providing information-theoretically secure message authentication. In addition, QKD integration is substantive: the experimental platform employs a modular QKD device with optical pulses at the telecommunication wavelength of 1.55 μm and a 10 MHz repetition rate, using single-photon detectors, and it supplies authentication keys for selected links in a small network experiment.

The reported results include the successful operation of a four-node blockchain experiment in which a malicious node attempting double-spending is filtered out during the broadcast protocol, enabling the formation of a block containing only legitimate transactions. Nevertheless, the limitations are primarily scalability- and infrastructure-related, including key rates, link provisioning, and the need for efficient consensus as the node count grows. Consequently, the study identifies a gap in developing efficient and scalable consensus and authentication designs that remain practical as quantum-safe requirements interact with QKD network constraints.

The study by [42] (TC = 180 and TC/year = 60.00) surveys emerging trends in computational science by jointly discussing quantum computing, artificial intelligence, high-performance computing, edge computing, and cybersecurity considerations. In this sense, the contribution is integrative and agenda-oriented, with emphasis on interdisciplinary collaboration, education, scalability, and ethical dimensions that cut across these paradigms.

Within this broad synthesis, blockchain is included as a form of distributed ledger technology discussed beyond cryptocurrencies, with attention to decentralization and to consensus processes such as proof of work and proof of stake. However, the treatment remains conceptual and does not isolate a specific blockchain layer as the target of a concrete modification or design choice.

Similarly, the threat framing is broad, focusing on evolving cybersecurity risks and operational challenges. Although quantum computing is addressed for its potential security implications, it is discussed as a transformative paradigm rather than through a fully specified attacker model. Consistent with this level of abstraction, no post-quantum cryptographic mechanism is proposed or parameterized, nor is QKD integration discussed.

Accordingly, the results are presented as synthesized observations and future directions rather than experimental findings, which limits technical specificity. Nevertheless, the paper highlights gaps in the rigorous, data-driven evaluation of security impacts across these computing paradigms, as well as in practical guidance for implementing secure, scalable systems as next-generation computing becomes operational.

The study by [43] (TC = 121 and TC/year = 20.17) provides an overview of cybersecurity in logistics and supply chain management by reviewing defensive measures and identifying future research directions. In this regard, its contribution is a structured synthesis that not only maps the current state of the field but also highlights methodological shortcomings and underexplored areas in a domain where technology adoption is accelerating and, consequently, the attack surface is expanding.

Within this technology landscape, blockchain is considered a viable option for logistics and supply chains, particularly for traceability and integrity objectives. However, the study characterizes blockchain as being at an early stage of adoption in transport and logistics; therefore, its feasibility is primarily assessed at the operational and information management layers, where implementation constraints and integration challenges are particularly salient.

From a security perspective, the threat model focuses primarily on classical cybersecurity risks in logistics, including increased exposure driven by internet-based technologies. At the same time, it raises a forward-looking quantum risk by noting that many studies rely on one-way encryption schemes while overlooking threats in a future shaped by quantum computing techniques. Nevertheless, the analysis does not advance to concrete countermeasure design in this direction: no post-quantum cryptographic mechanism or parameter set is proposed, and no QKD integration is discussed.

The results are presented as key findings and research directions rather than as deployment-level evidence. Specifically, the study reports limited use of real cybersecurity data, scarcity of logistics-focused cybersecurity studies, limited adoption of quantitative approaches, a tendency to emphasize precautionary measures over recovery measures, and limited research attention to digital forensics. Accordingly, the limitations follow from the underlying evidence base, particularly the lack of real incident datasets. Consistent with these constraints, the study identifies gaps in empirical data access, quantitative modeling, recovery and forensic capabilities, and proactive consideration of quantum-era cryptographic resilience for logistics systems.

The study by [38] (TC = 117 and TC/year = 13.00) introduces a definition of post-quantum blockchain and proposes a secure cryptocurrency scheme built on a lattice-based signature mechanism intended to resist quantum computing attacks. In particular, the contribution combines (i) a new signature scheme based on lattice basis delegation and preimage sampling—including a double-signature structure intended to reduce correlation between messages and signatures—with (ii) a cryptocurrency transaction workflow that integrates the signature into a blockchain setting.

In terms of system scope, the blockchain context is a cryptocurrency ledger in which transaction validity and traceability depend on signatures. Accordingly, the affected layer is transaction authentication and key management, rather than the consensus or application-execution layers.

Regarding adversarial assumptions, the threat model explicitly targets quantum-capable attackers and considers canonical quantum-algorithm risks, including Shor’s and Grover’s algorithms, while simultaneously requiring resistance to classical attack methods. Moreover, the proposed definition of post-quantum blockchain imposes additional requirements on signature functionality, namely that signatures be linkable or traceable.

Consistent with these aims, the post-quantum mechanism is lattice-based and reduces security to the short integer solution (SIS) problem. The parameterization is explicit: a security parameter n, a prime modulus $q\ge 2$, and a lattice dimension satisfying $m\ge 5nlgq$, together with a collision-resistant hash function $H:{\{0, 1\}}^{*}\to {\mathbb{Z}}_q^{m\times m}$. The construction uses TrapGen to generate a public matrix and a short-basis trapdoor; basis delegation is then employed to derive user keys, while signing relies on preimage sampling with a Gaussian parameter chosen to satisfy the trapdoor requirements.

In contrast to the explicit post-quantum signature design, no QKD integration is considered. The results are primarily analytical, including correctness and one-more unforgeability under the SIS assumption, as well as a size-based efficiency comparison against other lattice signatures. However, the limitations follow from the absence of implementation-level evaluation and from the lack of system-level performance measurements under realistic network and storage constraints. Consequently, the study emphasizes that post-quantum blockchain research remains limited and that deployment-oriented evaluation and optimization are required beyond signature replacement.

The study by [44] (TC = 116 and TC/year = 16.57) surveys the integration of distributed ledger technologies with the Internet of Things by reviewing how ledger-based mechanisms can address IoT challenges across domains such as smart homes, transportation, supply chains, healthcare, and energy. In this sense, the contribution is a structured mapping that links application-level challenges to representative distributed ledger solutions and, subsequently, consolidates open issues, including security, scalability, multi-ledger interoperability, and post-quantum resilience.

Against this backdrop, the blockchain context spans both permissioned and permissionless designs used for IoT data sharing, coordination, and incentive mechanisms. Consequently, the affected layers are not confined to a single component; rather, they range from device identity and data provenance to consensus and application services, reflecting the heterogeneity of IoT deployment settings.

From a security standpoint, the threat framing includes conventional blockchain dependencies on cryptographic protocols as well as operational concerns associated with resource-intensive mining. Furthermore, it highlights quantum computing as a potential risk because it may undermine elliptic curve signature schemes and challenge proof-of-work assumptions via quantum speedups, as discussed in the prior-cited analyses. In response, post-quantum approaches are addressed at the level of candidate families, with lattice-based schemes particularly promising. However, the study emphasizes the difficulty of achieving energy-efficient and computationally efficient implementations on IoT devices and, therefore, does not advance to concrete parameter sets.

In parallel, no QKD integration is evaluated. The survey only notes conceptual proposals involving quantum networking ideas for ledger tamper resistance and acknowledges that implementations remain an open problem. Accordingly, the results reflect a survey perspective, emphasizing breadth of applications and open challenges rather than empirical benchmarks. Consistent with this synthesis, the study identifies gaps in large-scale validation of distributed ledger trust for IoT collaborations, in practical interoperability among multiple ledgers, and in deployable post-quantum security for constrained IoT environments.

The study by [45] (TC = 115 and TC/year = 38.33) reviews resource management in fog and edge computing for IoT applications by categorizing the problem space into computing resource provisioning, task offloading, scheduling, service placement, and load balancing, and by comparing artificial intelligence-based and non-artificial intelligence-based solutions. In addition, the contribution includes a systematic selection of articles, a synthesis of quality-of-service metrics and datasets, and an explicit identification of limitations and open challenges that shape current research directions.

Within this landscape, blockchain is discussed as a thrust technology that can be integrated with fog and edge frameworks, for instance, in IoT management to strengthen security aspects. Nevertheless, the treatment remains at the level of a potential integration option: it is not developed into a blockchain protocol design, and no specific blockchain layer is targeted for modification.

In parallel, the study does not define a quantum threat model. Instead, quantum computing is presented as a cutting-edge field whose practical applicability is still at an early stage in the surveyed corpus. Consistent with this positioning, no post-quantum cryptographic mechanism or parameterization is proposed, nor is any QKD integration advanced.

Accordingly, the results emphasize observed research trends, the distribution of evaluation tools and simulators, and the limited availability of real-time fog testbeds for validating deployed models. The limitations, therefore, follow from the scarcity of realistic experimental infrastructure in the underlying evidence base. In line with these constraints, the study highlights gaps in realistic experimental infrastructure, in clearer conceptualization of the emerging paradigm and the role of artificial intelligence, and in rigorous evaluation environments for integrating additional technologies—including blockchain and quantum computing—into resource management systems.

The study by [46] (TC = 113 and TC/year = 16.14) surveys security considerations for Internet of Things ecosystems by identifying threat vectors, attack types, weak points in devices and networks, and mitigation and risk reduction practices. Accordingly, the contribution is a consolidated security overview complemented by forward-looking design suggestions that consider disruptive technologies as potential building blocks for future IoT security architectures.

Within this framing, blockchain is presented as a foundation for decentralized machine-to-machine trust, enabling device identification and authentication without relying on central brokers. In addition, it is described as an integrity mechanism for firmware and data, based on continual hashing and verification anchored in blockchain records. Consequently, the affected layer is IoT identity and integrity management, rather than a specific public-blockchain consensus layer.

In parallel, the threat model remains broad and covers adversaries exploiting impersonation, spoofing, malware, and systemic weaknesses in IoT products. At the same time, quantum computing is explicitly identified as a future threat to classical cryptography: Shor’s algorithm is cited as enabling attacks on RSA and elliptic curve systems, motivating attention to post-quantum cryptography. In that context, post-quantum mechanisms are discussed at the family level rather than instantiated schemes, including code-based, lattice-based, hash-based, multivariate, and isogeny-based approaches, without parameterization. Moreover, no QKD integration is proposed.

Overall, the results are survey-based, emphasizing guidance and design considerations rather than empirical validation. Therefore, the limitations follow from the absence of system-level implementation evidence within the reviewed material. Consistent with these constraints, the study highlights gaps in scalable, manageable IoT security architectures, in standard identity and trust protocols for heterogeneous devices, and in practical migration plans for quantum-resistant cryptographic solutions coupled with blockchain-enabled trust management.

The study by [39] (TC = 86 and TC/year = 28.67) provides a broad, integrative review of the evolution of modern computing and its current challenges by synthesizing paradigms, trends, and open issues across a wide range of computing. In this sense, the contribution is conceptual and organizational: it offers a unified narrative that contextualizes emerging paradigms—including blockchain and quantum computing—within the broader landscape of computing systems.

Within this overarching synthesis, blockchain is discussed at a high level as a distributed ledger approach that supports security- and integrity-oriented data handling in IoT and real-time systems. Moreover, it is framed as an enabling element in service models such as blockchain as a Service and marketplace-style resource sharing. Consequently, the discussion primarily focuses on the system and service layers in distributed and fog settings, while consensus and operational resource constraints are treated as practical bottlenecks rather than targets for protocol redesign.

In parallel, the study does not define a formal threat model for blockchain systems. Instead, it provides a conceptual warning that advances in quantum computing could undermine contemporary encryption assumptions and, by extension, affect cryptography-dependent ecosystems, including those that rely on cryptocurrencies. However, the quantum threat framing remains qualitative and is not operationalized into explicit adversary capabilities or attack surfaces tied to particular blockchain layers.

Consistent with this level of abstraction, no post-quantum cryptographic mechanism is specified, implemented, or parameterized, and the study does not provide design guidance for selecting concrete post-quantum primitives for blockchain. Likewise, quantum key distribution is not integrated, modeled, or discussed as an architectural component.

The study, therefore, provides qualitative synthesis rather than experimental results. It highlights resource limitations and protocol instability in edge and fog environments, and notes the need for more efficient consensus techniques that reduce the burden of block sharing and copying. Accordingly, the limitations are inherent to the broad survey scope and to the absence of threat-model-driven evaluation linked to specific blockchain implementations. In line with these constraints, the study identifies open research needs for operationalizing blockchain in constrained distributed settings, particularly consensus approaches compatible with limited fog resources and unstable environments, and also indicates a broader gap in translating awareness of quantum impacts on encryption into concrete system-level migration pathways for cryptography-dependent platforms.

The study by [40] (TC = 21 and TC/year = 10.50) addresses the practical deployment gap between post-quantum cryptography and blockchain-enabled IoT by implementing a post-quantum digital signature pipeline on a low-cost microcontroller and demonstrating how a blockchain can validate signed IoT transactions. Accordingly, the scope is implementation-oriented: it combines an embedded realization with an application-facing interaction model and a domain case study, thereby contributing empirical evidence on feasibility under constrained resources.

In this setting, the blockchain component is framed as an IoT-to-ledger workflow in which the IoT device signs transaction payloads, and a blockchain-side component validates authenticity and integrity before ledger inclusion. Consequently, the primary affected layer is the cryptographic trust layer for transaction authentication and integrity. At the same time, the data layer is indirectly affected, as larger signatures and keys increase transaction and block footprints, potentially impacting storage and throughput constraints.

The design motivation is articulated under an adversarial assumption that includes quantum-capable attackers who can invalidate the security margin of widely deployed classical public-key mechanisms and can weaken hash-based security. Furthermore, the attacker model is extended to embedded threats: adversaries may exploit side-channel leakage and fault injection to recover secrets or to induce erroneous signing behavior, which the study treats as a practical risk in microcontroller deployments.

Within this threat context, the post-quantum mechanism is instantiated as a lattice-based digital signature, namely CRYSTALS-Dilithium at parameter set 5. The size profile is reported explicitly as a public key of 2592 bytes, a private key of 4864 bytes, and a signature of 4595 bytes. Moreover, the implementation uses a portable codebase suitable for embedded integration and is paired with countermeasures intended to reduce exposure to implementation attacks.

In contrast, no QKD integration is proposed or evaluated, and the quantum-readiness strategy is confined to post-quantum digital signatures within the described workflow. The study reports that the embedded implementation is viable on an ESP32-class platform and supports an end-to-end interaction in which the device can autonomously produce post-quantum signed transactions for blockchain-side validation. Nevertheless, it also emphasizes that key and signature sizes remain substantially larger than classical counterparts, which can inflate storage requirements and constrain scalability in long-lived or high-volume deployments. Accordingly, the evaluation is bounded by the selected algorithmic family, parameter set, and hardware platform, and broader scalability analyses and assessments of alternative algorithms are positioned as necessary extensions.

Overall, the study both identifies and addresses the lack of implementation-grounded evidence for integrating post-quantum signatures into blockchain-oriented IoT workflows on low-cost devices, while treating side-channel and fault threats as first-order concerns. In addition, it highlights the need for systematic scalability analysis of post-quantum signature size effects on blockchain storage and long-term operation across diverse IoT architectures and domains.

The following subsection examines how the broader semantic profile of the corpus is reflected in the Author Keywords space by identifying the most recurrent terms and the thematic configurations that characterize the domain’s evolution.

3.6. Author Keywords Word Cloud

Figure 5 summarizes the Author Keywords landscape through a word cloud in which term salience reflects keyword occurrence counts. The most frequent term is internet of things (90), followed by artificial intelligence (48) and authentication (48). Other recurrent terms in the post-quantum and quantum-security space include lattice-based cryptography (46), quantum key distribution (42), and quantum-resistant cryptography (33), together with more specific constructs such as learning with errors (10), ntru (9), and dilithium (7). Privacy-related terms are also frequent, including privacy-preserving (40), federated learning (37), zero-knowledge proofs (32), and homomorphic encryption (16), complemented by attribute-based encryption (10), access control (9), data privacy (12), and data integrity (10).

Within the blockchain-related space, the word cloud includes terms associated with infrastructure and protocol concerns, such as smart contracts (29), distributed ledger (21), cryptocurrency (20), bitcoin (15), consensus algorithm (17), proof of work (11), and decentralization (10), as well as platform references such as hyperledger fabric (6) and consortium blockchain (6). Terms associated with deployment and performance are also present, including scalability (17), edge computing (16), and cloud computing (22). Application-oriented descriptors include healthcare (34), internet of medical things (19), vehicular adhoc networks (vanets) (11), internet of vehicles (11), internet of drones (iod) (8), unmanned aerial vehicles (6), and industrial iot (9).

3.7. Co-Occurrence Network of Author Keywords

Complementing the frequency-oriented view provided by the Author Keywords word cloud, the co-occurrence network in Figure 6 shows how the most recurrent terms are jointly used within the same articles. Nodes represent keywords, links indicate co-occurrence relations, and the four color-coded clusters identify distinct but partially overlapping thematic concentrations.

The blue cluster is centered on internet of things (90), which appears as the main hub and is closely connected with artificial intelligence (48) and authentication (48). Other terms in this cluster include cybersecurity (30), machine learning (26), cloud computing (22), edge computing (16), healthcare (34), and internet of medical things (19).

The red cluster is organized around post-quantum and privacy-related terms. It is dominated by post-quantum cryptography and includes lattice-based cryptography (46), privacy-preserving (40), federated learning (37), zero-knowledge proofs (32), quantum-resistant cryptography (33), homomorphic encryption (16), and data privacy (12).

The green cluster is centered on quantum key distribution (42) and includes related terms such as quantum cryptography (22), quantum entanglement (12), 5g (12), 6g (25), e-voting (13), and quantum blockchain (20).

The purple cluster groups blockchain-related security and transaction terms, with digital signature (36) and encryption (29) as prominent nodes, linked to smart contracts (29), distributed ledger (21), cryptocurrency (20), bitcoin (15), proof of work (11), and public key (14). The network also shows visible links between this cluster and the IoT- and post-quantum-related clusters.

Taken together, the co-occurrence network shows that the keyword space is structured around four partially overlapping thematic concentrations, with visible links among IoT-related, post-quantum, privacy-oriented, quantum-communication, and blockchain-security terms. The following subsection extends this relational view by presenting the thematic map derived from Author Keywords, which positions the main themes according to their centrality and density.

3.8. Thematic Map of Author Keywords

Building on the relational evidence provided by the co-occurrence network, the thematic map in Figure 7 synthesizes the Author Keywords space into macro-themes positioned by relevance degree (centrality) and development degree (density). This representation distinguishes themes located in the motor themes, niche themes, basic themes, and emerging or declining themes quadrants.

In the motor themes quadrant, two highly central and dense themes are visible. One group’s blockchain transaction and security-related terms, including digital signature, smart contracts, quantum cryptography, quantum blockchain, and scalability. The second group of IoT- and AI-related security and deployment terms, including artificial intelligence, cybersecurity, machine learning, cloud computing, and 6g.

In the niche themes quadrant, the map shows a cluster centered on privacy- and lattice-related terms, including privacy-preserving, lattice, lattices, internet of medical things, and data privacy. A smaller grouping located near the horizontal boundary on the left side includes quantum key distribution, blockchain technology, smart grid, data integrity, and smart city.

The basic themes quadrant contains a cluster focused on post-quantum and privacy-related mechanisms, grouping post-quantum cryptography, lattice-based cryptography, federated learning, quantum-resistant cryptography, and zero-knowledge proofs. A second cluster near the centrality axis includes internet of things, authentication, healthcare, encryption, and iot security.

Finally, the emerging or declining themes quadrant includes terms such as distributed ledger, cryptocurrency, bitcoin, deep learning, and peer-to-peer (p2p) networks.

4. Discussion

This section interprets the evidence reported in the performance and thematic results by linking corpus construction choices to observed growth dynamics, the geographic and institutional structure of production, dissemination channels, the influence profile of highly cited contributions, and the semantic organization of the field through Author Keywords. The overall aim is to clarify what the mapped structures imply for the development of quantum-safe blockchain research and for consolidating research fronts at the intersection of ledger systems and quantum-era security assumptions.

4.1. Acceleration of the Field and the Consolidation of a Recent Research Surge

The temporal evidence indicates that quantum-safe blockchain has evolved from a nascent topic into a rapidly expanding research domain within a short period. As shown in Section 3.1, publication output remained limited in the early years, increased steadily through 2022 and 2023, and then accelerated sharply in 2024 and 2025, with the corpus reaching 648 records by early 2026. Because the 2026 value corresponds to records retrieved only up to 9 February, it should be interpreted as a partial-year count rather than as directly comparable to the preceding full-year totals.

In substantive terms, this growth suggests that quantum threat framing and post-quantum mitigation are no longer treated as peripheral concerns, but increasingly operate as recurrent design constraints across applied blockchain contexts. The surge also indicates that quantum-safe requirements are becoming embedded in mainstream blockchain-adjacent domains, particularly in large-scale connected and resource-constrained environments, rather than remaining confined to cryptography-centered discussions or isolated proof-of-concept studies. This interpretation is consistent with recent security reviews that position quantum-resilient mechanisms as a near-term requirement in the Internet of Everything and next-generation network environments, where distributed ledger technologies and AI-enabled security are treated as enabling components [30,31,32,34].

At the methodological level, the corpus is the result of a high-sensitivity search design that explicitly targets the intersection between blockchain systems and quantum threat models or countermeasures. The PRISMA-guided retrieval and filtering workflow clarifies that the final analytical set comprises 648 records after deduplication (690 removed) and standardized filtering by language and document type, as described in Section 2. This workflow supports an interpretation in which the observed growth is unlikely to be a mere artifact of broad blockchain or broad quantum research, because it is tied to conjunctive retrieval (G1 AND G2) and is further refined by eligibility controls and subsequent keyword preprocessing for thematic mapping.

4.2. Geographic Concentration, Collaboration Structure, and Leadership Profiles

The geographic distribution confirms that the field is globally distributed but strongly concentrated in a subset of countries, particularly in Asia, as displayed in Section 3.2.1. China and India clearly anchor the country-level production map, followed by a smaller second tier of contributors and a broader international footprint spanning North America, Europe, Africa, Latin America, and Oceania. This pattern suggests that quantum-safe blockchain is not confined to a single regional ecosystem; however, the leading volume is concentrated in countries that also tend to sustain strong research activity in IoT, 6G, and applied security, which is consistent with the IoT-centric thematic backbone observed in the Author Keywords space, displayed in Figure 5. Complementary scientometric studies centered on secure IoT and IoT security paradigms report a similarly concentrated country-level structure, with India and China consistently appearing among the leading contributors in quantum-safe and blockchain-adjacent IoT security directions [28,29].

The international collaboration network further indicates that production is not only concentrated but also organized around a small set of hubs that structure cross-country connectivity, as shown in Figure 4. China and India are the most prominent nodes, and the community structure indicates that collaboration is not uniform but clustered around regionally coherent and cross-regional linkages. In substantive terms, the field appears to be shaped by both geographically concentrated collaboration blocs and bridging ties that connect Asia, the Middle East, Europe, and North America. This pattern may influence the diffusion of technical choices such as post-quantum primitive selection, system integration targets, and evaluation practices.

Corresponding author country profiles provide an additional leadership lens that complements affiliation-based production (Table 1). As shown in the table, the leading contributors do not share a uniform internationalization profile: some remain predominantly single-country-publication oriented, whereas others display comparatively stronger multiple-country-publication participation. This distinction matters because MCP-oriented profiles may reflect stronger cross-institutional and cross-country integration of expertise, which is often required in quantum-safe blockchain research where cryptography, networking, embedded systems, and domain deployment constraints intersect. At the same time, the coexistence of SCP-dominant and MCP-oriented profiles suggests that visible leadership in the field is compatible with different organizational modes of research production.

These indicators, based on country output and corresponding authorship, should be interpreted as descriptive signals of publication concentration and collaboration structure, rather than as direct measures of scientific quality, causal leadership, or technical superiority. In particular, within the full counting and corresponding author frameworks used here, the reported values are most informative for identifying visible participation patterns across the mapped corpus.

4.3. Institutional Structure and Dissemination Channels

At the institutional level, the most relevant affiliations show concentration in a small set of organizations with strong links to communications, cybersecurity, and applied computing ecosystems, as described in Section 3.3. The leading affiliations are accompanied by a broader tail of institutions at intermediate production levels, indicating that the field combines a limited number of highly visible institutional hubs with a wider contributing base. The prominence of institutions from China, Saudi Arabia, and India is consistent with the country-level concentration in Figure 3 and the hub structure in Figure 4, suggesting that large parts of the field are shaped by institutional clusters that likely share common applied contexts such as IoT infrastructures, next-generation networks, and security engineering.

The source distribution further indicates that the field is disseminated primarily through engineering, security, and applied computing outlets rather than being confined to specialist cryptography venues, as shown in Section 3.4. The leading sources are concentrated in high-visibility journals, while a broader second tier spans Q1–Q3 outlets in networking, information security, cryptography, and applied systems research. This dissemination structure is consistent with a field in which quantum-safe blockchain is frequently treated as an engineering and deployment problem, including IoT, edge, networked, and smart-contract-oriented settings, rather than solely as a formal cryptographic design problem.

At the same time, source-level frequencies should be interpreted cautiously. They indicate where the mapped corpus is most visibly disseminated, but they do not by themselves establish the intrinsic methodological quality, technical depth, or field-defining status of any individual venue. From a reader-access perspective, it is also worth noting that source visibility does not necessarily coincide with practical accessibility. Although open-access status was not treated as a coded analytical variable in this review, access conditions may still influence how easily readers can consult, reuse, and disseminate the literature mapped in this field.

4.4. Influence Profile of Highly Cited Contributions and What It Implies for Research Maturity

The focused set of most salient studies clarifies the influence structure of the corpus by combining highly cited foundational contributions with more recent works that show strong citation dynamics, as presented in Section 3.5. Overall, the influence profile indicates that quantum-safe blockchain research develops through two coupled pathways. The first pathway is integrative and survey-driven, embedding quantum risk as a cross-cutting constraint within large application ecosystems such as 6G, IoT, and emerging socio-technical platforms. This pathway is represented by broad surveys and roadmaps in 6G security and privacy [35,36], the high-impact survey on metaverse-oriented healthcare [41], and other widely cited overviews that frame quantum-safe blockchain within broader deployment and governance agendas. The second pathway is mechanism-centered, focusing on explicit quantum-resilient security components at the ledger trust layer, including post-quantum signature replacement and, in selected cases, QKD-supported authentication designs. This pathway is reflected most clearly in the early quantum-resilient ledger studies [37,38] and, more recently, in implementation-oriented evidence such as [40]. In this sense, the predominance of survey and roadmap-oriented studies within the salient set should not be interpreted as a mismatch in the selection logic, but rather as a signal of the current maturity profile of the field. Specialized surveys focusing specifically on post-quantum signature families and comparative quantum-resistant blockchain constructions complement this picture by providing mechanism-focused consolidation that is typically outside the scope of application-driven roadmaps [24,27]. Complementary surveys on post-quantum adoption at the protocol and infrastructure layers reinforce the same point, showing that implementation realism is often governed by integration and benchmarking constraints in networking protocols and public key infrastructures rather than by primitive selection alone [20,21].

The qualitative synthesis of the salient studies further shows that quantum threat framing is unevenly operationalized across the most influential contributions. Several highly cited surveys treat quantum computing primarily as a strategic risk to public-key cryptography, often referencing canonical algorithmic implications such as Shor-related compromises of RSA and elliptic curve cryptography, while leaving post-quantum instantiation at the level of candidate classes rather than parameterized implementations [35,36,44,46]. By contrast, mechanism-driven studies provide more direct technical evidence. Study [37] replaces digital signatures with information-theoretic message authentication supported by QKD-supplied shared keys in a Byzantine fault-tolerant ledger setting, thereby offering the clearest blockchain-level experimental validation within the salient set. Study [38] proposes a lattice-based signature construction reduced to the SIS problem and specifies key parameters and construction elements. More recently, ref. [40] provides implementation-grounded evidence by deploying a lattice-based signature pipeline using CRYSTALS-Dilithium parameter set 5 on a low-cost microcontroller and demonstrating a blockchain-side validation workflow, explicitly reporting public key, private key, and signature sizes together with the associated storage and scalability implications. Taken together, these contrasts indicate that the field is expanding in breadth through surveys while advancing in technical depth through a smaller set of mechanism-centered and implementation-oriented contributions.

From a maturity standpoint, this influence profile reveals a persistent transition gap. A substantial share of high-impact work remains taxonomic, prospective, or agenda-oriented [35,36,39,42], whereas empirically grounded quantum-safe integration is still comparatively limited and localized to specific architectural choices, notably QKD-supported permissioned designs in [37] and lattice-signature integration in [40]. This asymmetry suggests that broad recognition of quantum-era risk has advanced faster than the production of parameterized, deployment-ready quantum-safe architectures that account for resource constraints, system-layer interactions, and operational attack surfaces.

4.5. Thematic Structure: Coupling of IoT Deployment, Post-Quantum Migration, Privacy, and Quantum Communication

Taken together, the Author Keywords results indicate that quantum-safe blockchain research is organized around a strongly application-driven thematic backbone in which IoT deployment contexts provide the main integrative setting for security and trust design. Across the thematic outputs reported in Section 3.6, Section 3.7 and Section 3.8, internet of things consistently occupies a central position, accompanied by artificial intelligence, authentication, and a broader set of deployment and security terms. This convergence suggests that the field is shaped less by abstract cryptographic transition alone than by the need to sustain trust, coordination, and data protection under resource-constrained, networked, and application-facing conditions. In this sense, quantum-safe blockchain appears thematically embedded in broader IoT-oriented security ecosystems rather than developing as an isolated cryptographic niche.

A second recurrent pattern is the close association between post-quantum migration and privacy-preserving design. The combined evidence from keyword frequency, co-occurrence structure, and thematic positioning indicates that lattice-based cryptography, quantum-resistant cryptography, privacy-preserving, federated learning, and zero-knowledge proofs form a stable conceptual grouping rather than separate lines of discussion. This matters interpretively because it suggests that the field is moving beyond a narrow substitution narrative in which classical signatures are merely replaced by post-quantum alternatives. Instead, migration is increasingly framed as part of a broader systems problem in which cryptographic transition, privacy preservation, and data-governance requirements must be addressed jointly. The presence of more specific terms such as learning with errors, ntru, and dilithium further indicates that at least part of the corpus reaches a non-trivial level of cryptographic specificity, which is consistent with the broader post-quantum landscape in which lattice-based constructions remain a central design space for quantum-resilient primitives [22]. Likewise, the recurrent association with privacy-enhancing mechanisms is consistent with focused syntheses that position ZKP-enabled and related privacy-preserving designs as co-requirements for post-quantum blockchain migration, including in IoMT-oriented settings [25,26], while recent work on commitment-oriented primitives also suggests that migration increasingly involves auxiliary building blocks beyond signatures and KEMs [23].

A third thematic implication concerns the position of quantum communication, particularly QKD. The keyword evidence shows that QKD is neither absent nor marginal; rather, it appears as a visible but comparatively specialized direction. Its thematic placement, together with its co-occurrence links to terms such as 6g, e-voting, smart grid, and smart city, suggests that it is more often framed in infrastructure-oriented and system-level discussions than in large-scale implementation-centered blockchain studies. This distinguishes QKD from the more central IoT-driven and post-quantum migration themes: whereas the latter occupy broader and more connected positions in the thematic structure, QKD remains more context-dependent and less fully integrated into the dominant application backbone. The result is a thematic field in which quantum communication is conceptually important, but structurally less central than post-quantum cryptographic migration tied to IoT and privacy requirements.

Finally, the thematic map helps clarify the maturity profile of these interactions. The motor themes show that the most field-shaping activity is concentrated at the intersection of blockchain security primitives and IoT- or AI-oriented deployment environments, where trust, scalability, and operational performance remain tightly coupled. By contrast, the privacy- and lattice-related niche theme appears cohesive but comparatively specialized, suggesting an internally mature line that has not yet become the dominant organizing center of the field. The basic themes reinforce this reading by showing that post-quantum and privacy-enhancing constructs are broadly relevant but not yet fully consolidated into a single dense macro-theme. In parallel, the placement of distributed ledger, cryptocurrency, bitcoin, and related terms in the emerging or declining quadrant suggests that, within this corpus, generic blockchain descriptors no longer function as the primary thematic drivers of the quantum-safe intersection. Overall, the combined thematic evidence indicates that quantum-safe blockchain is evolving as a coupled systems-oriented research space in which IoT deployment, post-quantum migration, privacy-preserving design, and selected quantum communication directions interact unevenly but persistently across the literature.

4.6. Data-Lifetime-Sensitive Interpretation of Quantum Threats in Blockchain Systems

A recurring limitation in the reviewed literature is that quantum threat is often framed at a strategic or generic level, without clearly distinguishing the temporal profile of the asset at risk. In blockchain-related systems, however, quantum exposure is not uniform across the stack. Some risks concern the future confidentiality of protected information that may remain sensitive for long periods, whereas others concern active integrity and authorization failures during live operation. Treating these exposures as analytically equivalent obscures migration priorities, because not all blockchain layers become critical under the same threat timing or for the same security property.

A first category concerns retrospective confidentiality risks affecting long-lived protected data. These risks arise when information encrypted or otherwise protected today may still need to remain confidential at a later time when more capable quantum adversaries become available. In blockchain settings, this issue is not restricted to on-chain records, many of which are intentionally public, but extends to sensitive off-chain data, credential material, key-establishment processes, and application contexts in which the ledger anchors access, provenance, or integrity for data that retains value over long protection horizons. This perspective is particularly relevant in IoT-, healthcare-, and infrastructure-oriented settings, where blockchain is used as a trust layer while the underlying data ecosystem may include persistent sensitive information [40,44,46]. From a migration standpoint, these confidentiality-sensitive contexts may justify earlier transition planning even when active transaction forgery is not yet the dominant concern.

A second category concerns active integrity and authorization risks during live blockchain operation. Here, the primary issue is not delayed disclosure of past information, but the possibility that a quantum-capable adversary could compromise transaction authorization, identity binding, or state-transition integrity once classical public-key assumptions no longer hold. This threat directly affects the cryptographic trust layer of blockchain systems, especially transaction signatures, ownership transfer, and key management. Several studies in the salient set approach the problem from this perspective, either by proposing post-quantum signatures for cryptocurrency settings or by implementing quantum-resistant signing workflows for blockchain-enabled IoT devices [38,40]. Under this exposure model, migration priority concentrates on those functions whose failure would undermine immediate system correctness, including transaction validity, account control, and authorization semantics.

A related implementation-level risk within this live authorization layer concerns stateful hash-based signature schemes. Although hash-based signatures are an important post-quantum direction, not all such schemes impose the same operational conditions. In particular, stateful constructions such as XMSS and LMS require strict one-time state progression, so that each signing state or index is consumed only once. In blockchain-oriented deployments, this creates an additional systems-level dependency that differs from classical signature replacement: security depends not only on the soundness of the primitive, but also on correct persistent state handling under real operating conditions, including rollback, backup restoration, synchronization failures, and concurrent transaction generation. As a result, wallet-, device-, or validator-side state discipline becomes part of the effective security model. From a migration perspective, the transition toward stateless alternatives removes this category of state-reuse failure and therefore offers greater operational robustness when reliable state persistence cannot be guaranteed. However, this shift may come at the cost of larger signatures and stronger transaction-footprint inflation, which can intensify pressure on block occupancy, propagation overhead, and long-term ledger growth. In this sense, migration from stateful to stateless hash-based signatures should be interpreted as a trade-off between operational safety and ledger-level overhead rather than as a purely cryptographic substitution.

A third category concerns consensus- and control-plane risks, which are related but not reducible to either long-term confidentiality or user-level signature forgery. These include quantum-enabled advantages against hash-based mining assumptions, message authentication between nodes, and communication-layer trust mechanisms that sustain consensus formation. The salient evidence shows that this layer deserves separate attention. In particular, the experimental quantum-secured blockchain reported in [37] explicitly distinguishes the vulnerability of digital signatures from the mining-related implications of quantum search advantage and responds by shifting authentication toward shared-key mechanisms supported by quantum key distribution. This indicates that quantum-safe migration is not always exhausted by replacing user-facing signature algorithms; in some architectures, it also requires revisiting node authentication, consensus assumptions, and the trust model of the communication substrate.

A further point follows from the control-plane perspective and deserves explicit clarification when QKD is considered as a quantum-safe direction for blockchain systems. QKD is not trust-neutral. In current realizations, QKD networks typically rely on pre-established communication infrastructure, trusted-node assumptions, or tightly controlled link configurations for key distribution and authentication support. This creates a fundamental tension with the trust model of public blockchains, whose security logic is built around open participation and the absence of prior trust between network actors. The salient evidence illustrates this tension clearly. Study [37] does not treat QKD as a direct drop-in enhancement for a fully open blockchain; rather, it implements QKD-supported authentication in a permissioned Byzantine fault-tolerant setting, where the communication substrate and participating nodes can be more tightly governed. Accordingly, the relevance of QKD to blockchain should be interpreted as architecture-dependent. It is more naturally aligned with permissioned or consortium environments in which network control, institutional governance, and trusted relay assumptions can be made explicit, whereas its integration into public blockchains raises a deeper conflict between physical-layer trust dependencies and the decentralized security model of open ledger participation.

Table 6. Data-lifetime-sensitive structuring of quantum threats in blockchain systems.

Threat Category	Typical Blockchain Layer Affected	Migration Implication
Retrospective confidentiality risks to long-lived protected data	Off-chain data ecosystem, access-control and credential layers, key-establishment interfaces, and blockchain-supported trust architectures in long-horizon application contexts.	Prioritize earlier migration in contexts where secrecy duration matters, even if immediate transaction forgery is not yet the dominant operational concern.
Active signature and authorization risks in live blockchain operation	Transaction-signing layer, key management, account control, and user- or device-level authorization mechanisms.	Prioritize post-quantum signatures and related identity mechanisms where failure would directly compromise transaction validity, state-transition correctness, or asset control.
Consensus- and control-plane risks	Consensus, mining or validation logic, node authentication, message-authentication workflows, and communication-trust substrate.	Prioritize protocol-level redesign where needed, including stronger authentication assumptions, revised hash-security margins, and, in selected permissioned settings, specialized mechanisms such as QKD-supported authentication.

summarizes this distinction by relating each threat category to the typical blockchain layer affected and its corresponding migration implication.

This synthesis is derived from the reviewed corpus rather than from a uniformly articulated taxonomy in the literature. Although quantum risk is often framed at a broad strategic level, the salient studies indicate that exposure is not temporally uniform across blockchain systems. In particular, study [37] distinguishes signature-related and mining-related quantum vulnerabilities while relocating authentication to QKD-supported shared-key mechanisms; studies [38,40] foreground active signature and authorization exposure; and studies [44,46] situate the problem in IoT-oriented trust architectures where long-lived protected data and identity functions remain relevant.

Taken together, these distinctions suggest that quantum-safe blockchain migration should be interpreted as a data-lifetime- and layer-sensitive transition problem rather than as a single undifferentiated upgrade. If the dominant exposure concerns long-lived protected data, the relevant priority is to protect confidentiality before delayed compromise becomes feasible. If the dominant exposure concerns live authorization and transaction integrity, migration priority shifts toward post-quantum signatures and related identity mechanisms. If the dominant exposure lies in the control plane, then protocol-level redesign, stronger assumptions for node authentication, and, in selected permissioned settings, specialized mechanisms such as QKD-supported authentication may become more relevant than signature replacement alone [37,38,40]. A clearer distinction among these temporal and functional threat profiles would improve comparability across studies and make migration priorities more interpretable across blockchain layers and deployment contexts.

4.7. Implications for the Development of Quantum-Safe Blockchain Research

Across the performance, influence, and thematic evidence, the mapped field suggests a transition from broad problem recognition toward a more demanding phase of system-oriented consolidation. The central implication is that future progress will depend less on reiterating the relevance of quantum risk and more on translating that awareness into technically explicit and context-sensitive design choices. In practical terms, this means that blockchain-related quantum-safe research should increasingly specify which blockchain layer is being protected, which threat exposure is prioritized, which cryptographic mechanism is adopted, and under which deployment conditions the proposed solution is expected to remain viable. Without this level of articulation, the literature risks continuing to grow in visibility while remaining difficult to compare, reproduce, and aggregate into reusable system knowledge.

A second implication concerns evaluation maturity. The current evidence shows that the field still combines survey-dominant influence with a smaller body of mechanism-centered and implementation-grounded contributions. This asymmetry suggests that the next stage of development should prioritize benchmarkable and auditable studies that move beyond conceptual positioning or family-level references to post-quantum cryptography. In particular, stronger progress will require explicit parameter reporting, workload-aware evaluation, and systematic analysis of ledger-level trade-offs in storage, throughput, latency, propagation overhead, and operational complexity. This need is reinforced by surveys on post-quantum integration in networking protocols and public key infrastructures, which show that deployment realism is often constrained not only by primitive selection, but also by certificate formats, protocol negotiation, benchmarking methodology, and implementation context [20,21].

A third implication is that architectural differentiation should become more explicit across the literature. The reviewed corpus indicates that quantum-safe blockchain cannot be treated as a single migration pathway equally suitable for all settings. Instead, different architecture classes face different integration logics. In constrained and application-facing environments, especially those involving IoT and edge-oriented deployments, practical feasibility depends on balancing cryptographic robustness with resource limits, communication overhead, and long-term storage effects, as reflected in both the salient studies and the broader thematic structure [35,36,40,44,46]. In parallel, approaches that involve quantum communication should be assessed under architecture-specific trust assumptions rather than treated as universally transferable solutions. In particular, substantive QKD integration remains concentrated in specific protocol designs and experimental settings [37], which indicates that its practical value depends on whether the underlying blockchain environment can accommodate the corresponding infrastructure, governance, and communication requirements.

Finally, the interaction between dissemination patterns and evidence maturity suggests that the research front is increasingly shaped in engineering and applied security venues that emphasize deployability, integration, and performance constraints. This venue structure can accelerate the movement from conceptual roadmaps toward implementable architectures, but it also raises the standard for what should count as persuasive evidence. A key developmental trajectory for the field is therefore the conversion of broad quantum-safe narratives into validated, scalable, and context-aware blockchain designs supported by reproducible evaluation practices and technically transparent reporting [31,32]. Under this trajectory, the most valuable future contributions will likely be those that connect threat assumptions, exact cryptographic instantiations, blockchain-layer effects, and measurable system outcomes within clearly delimited deployment scenarios.

4.8. Limitations of This Review

This bibliometric review has several limitations that should be acknowledged when interpreting the scope of the mapped evidence. First, it is constrained to two databases and to journal articles, which may limit the representation of relevant contributions disseminated through other indexing environments or publication formats. This restriction also implies that some early-stage or implementation-oriented contributions disseminated through conference venues may be underrepresented, particularly in fast-moving technical areas where conference publication is common. It may also affect the geographic profile of the mapped corpus, because reliance on journal articles can underrepresent regions or research communities in which high-quality conference dissemination plays a comparatively stronger role.

Second, the mapping relies primarily on bibliographic metadata and keyword-level structures rather than full-text modeling, which conditions the granularity of the thematic representation. In addition, the preprocessing of Author Keywords necessarily involved analytical judgment. Although the cleaning step was intended to improve thematic discrimination by reducing generic anchor terms, alternative preprocessing decisions could produce some variation in cluster prominence, thematic boundaries, or the relative visibility of specific descriptors.

A further limitation concerns the search design. Although the query was intentionally designed for high sensitivity at the intersection of blockchain systems and quantum-related security, it still relies on explicit lexical markers in titles, abstracts, and indexed keywords. Consequently, relevant studies may be underrepresented when they address cryptographic migration, future security resilience, or architecture-level adaptations without using the selected blockchain- and quantum-oriented terminology directly. In addition, studies centered on specific post-quantum schemes, implementation contexts, or blockchain platforms may not be fully captured if they do not frame their contribution through the vocabulary operationalized in G1 and G2. The resulting corpus should therefore be interpreted as a structured and transparent map of the explicitly articulated intersection, rather than as an exhaustive representation of all adjacent work that may be relevant to quantum-safe blockchain design.

5. Conclusions

This bibliometric review provides an evidence-based map of the quantum-safe blockchain landscape by linking three elements that are often examined in isolation: quantum threat assumptions, post-quantum cryptographic building blocks, and blockchain-oriented integration contexts, including quantum key distribution. By consolidating 648 journal articles retrieved through a PRISMA-guided workflow from Scopus and Web of Science, the study establishes a structured baseline that supports positioning new contributions, selecting representative subareas, and designing comparable evaluation pathways. Its added value lies in combining bibliometric structure with targeted technical interpretation, thereby moving beyond a purely descriptive mapping and offering a clearer basis for evaluating how threat models, cryptographic choices, and blockchain-layer implications are currently articulated across the literature.

Three overarching implications emerge from the mapping. First, research activity has transitioned from predominantly conceptual risk articulation toward engineering-oriented integration questions, where feasibility, overhead, and deployment constraints become first-order drivers of research emphasis. Second, the semantic backbone of the field is anchored in IoT, facing trust establishment and authentication challenges, while post-quantum mechanisms and privacy-preserving primitives are broadly relevant enablers that cut across application contexts. Third, quantum key distribution forms a coherent but more specialized stream whose practical relevance depends on explicit articulation of network constraints, trust assumptions, and scalability interactions with ledger operations, rather than on generic claims of quantum security.

A central conclusion is therefore not merely that quantum-era risk is recognized, but that comparability and maturity are currently constrained by uneven reporting discipline. Progress toward deployable quantum-safe blockchain designs will depend on making system claims auditable. In practical terms, this requires consistent specification of threat assumptions, explicit post-quantum parameter sets, and transparent translation of cryptographic choices into ledger-level costs in storage, throughput, latency, and operational complexity. Without these elements, the literature remains difficult to aggregate and to translate into reusable design patterns.

In order to operationalize this requirement,

Table 7. Minimum reporting set for auditable and reproducible evaluation of PQC integration in blockchain systems.

Reporting Dimension	Minimum Information to Report	Why It Matters
Threat model and blockchain context	Blockchain type (public, permissioned, or hybrid), affected layer (e.g., transaction signing, consensus, smart contracts, control plane, off-chain trust layer), exposure type (retrospective confidentiality, active authorization/integrity, or consensus/control-plane), and assumed adversarial capabilities (e.g., Shor-type, Grover-type, side-channel, fault injection).	Makes security claims interpretable and allows readers to determine which blockchain layer and threat timing the evaluation actually addresses.
PQC mechanism and parameterization	Exact scheme name, cryptographic family, parameter set, security level, hybrid composition if applicable, and sizes of public key, private key, signature, ciphertext, or other relevant cryptographic artifacts.	Prevents vague references to “post-quantum” mechanisms and enables technically meaningful comparison across studies.
Implementation environment	Hardware platform, processor class, memory profile, operating system or firmware environment, software stack, compiler settings, cryptographic library or codebase version, and number of nodes if a distributed experiment is involved.	Establishes the execution context needed to reproduce performance results and interpret feasibility claims.
Blockchain and workload configuration	Consensus mechanism, block size or equivalent capacity constraint, transaction format, workload type, transaction rate, benchmark duration, validation setting, network topology, and whether results derive from simulation, emulation, testbed, or deployed prototype.	Ensures that ledger-level effects are not interpreted in isolation from the operational conditions that generate them.
Ledger-level performance metrics	Transaction footprint, block occupancy or block-space usage, throughput, end-to-end latency or finality latency, propagation overhead, and storage growth over time.	Translates cryptographic design choices into system-level blockchain costs, which are central to deployment viability.
Cryptographic execution metrics	Key generation time, signing time, verification time, encapsulation or decapsulation time if applicable, and any batching or aggregation behavior used in the evaluation.	Allows assessment of whether the proposed mechanism is viable for the intended application layer and workload profile.
Resource and energy metrics	CPU utilization, memory consumption, communication overhead, and energy consumption or power profile, especially for constrained IoT, edge, or embedded environments.	Clarifies whether a scheme is practical under resource-constrained deployment conditions rather than only in abstract security terms.
Security-relevant implementation details	Countermeasures against side-channel or fault attacks if applicable, key-management assumptions, authentication assumptions between nodes, hash-security margins, and observed scalability or failure limits.	Makes implementation security explicit and prevents system claims from relying on hidden or unrealistic assumptions.
Reproducibility artifacts	Availability of code, scripts, configuration files, datasets or benchmark workloads, measurement procedure, random seeds when relevant, and sufficient documentation to reconstruct the experiment.	Enables independent verification and turns isolated demonstrations into reusable evidence for cumulative research.

proposes a minimum reporting set for future studies that evaluate post-quantum cryptographic integration in blockchain systems. The purpose is not to impose a single benchmarking protocol across heterogeneous architectures, but to identify the technical information that should be reported at a minimum in order to make system claims auditable, reproducible, and comparable across deployment contexts. The proposed set covers threat assumptions, exact cryptographic instantiation, implementation environment, blockchain and workload configuration, ledger-level performance effects, computational overhead, security-relevant implementation details, and reproducibility artifacts.

It is important to note that the proposed reporting set is intended as a minimum common baseline for studies evaluating PQC integration in blockchain systems. It is not meant to replace domain-specific benchmarking practices, but to ensure that claims about feasibility, scalability, and quantum resilience are stated with enough technical detail to support auditability and cross-study comparison.

Future work can be organized around three priority directions. The first is reproducibility and comparability, including standardized reporting templates and benchmarkable workloads. The second is system co-design, in which protocol integration, governance constraints, and security objectives are treated as coupled design variables rather than sequential add-ons. The third is targeted QKD integration, focused on clearly delineating when QKD-supported components provide incremental value under realistic network and operational constraints, and how that value interacts with blockchain scalability and trust models.