Blockchains

Document validation and authenticity remain critical challenges due to the risk of fraud and the need for secure and trustworthy processes. This paper presents RadChain, a system that links physical documents to a blockchain record through radio-frequency tags. The proof of concept implements the Near-Field Communication (NFC) pathway; other Radio-Frequency Identification (RFID) tags that can provide the same URL or hash are supported by design but were not tested. RadChain places a lightweight edge service close to the user, with the intended benefit of reducing latency and load on the blockchain node, and uses Alastria, a hybrid public–private blockchain platform, to balance security, privacy and transparency. Each physical document carries an NFC tag storing a URL that embeds the SHA-256 hash of the document, which can be certified, signed and queried against a smart contract through a decentralized application. A successful verification shows that the hash was registered, and by which accounts and when; whether those accounts are trusted is decided by an explicit on-chain authorization registry plus the verifier’s policy, and the check relies on the assumption that the tag is securely bound to the physical document, since retrieving a registered hash does not verify the current printed content. A functional evaluation on the Alastria network covers valid, modified, unregistered and duplicate-operation cases and reports preliminary measurements of the edge service on a Raspberry Pi 4 and a Raspberry Pi 5 (a registered-hash verification takes a median of 28 and 14.5 ms, respectively, measured on the device with a localhost client and therefore excluding the smartphone-to-device hop) and of the blockchain operations. The results show that combining NFC tags with blockchain provides a practical mechanism to trace documents and check the registration of their hash, which may help reduce document fraud in sectors that demand high levels of security, such as the legal system.

A common worry about depeg predictors is that an adversary who manipulates oracle prices can blind them. We test it on a new multi-source corpus of twelve historical stress episodes across nine assets and three chains. Under retrospective leave-one-event-out testing, the reconstructed models span 0.558–0.772 ROC-AUC, with our reference predictor at 0.762; the source papers report different metrics and tasks that are not directly comparable. Manipulable price features hurt out-of-event generalization: on the seven-episode live-feed subgroup, retained features reach 0.75 AUC versus 0.72 for the full model, directional, not significant at seven events. We define the Oracle Manipulation Index (OMI), prove that shifting the aggregate by $\delta$ while one honest feed survives forces the unnormalized cross-feed price range to be at least $\delta /L$ for L-Lipschitz aggregators, and measure on a Foundry mainnet fork (Curve 3pool, block 25,238,878) that a 0.1% move requires about USD 50 M in deployed capital. Excluding individually affordable channels gives a sufficient input-invariance rule under fixed channel costs; the robust subset matches clean accuracy and degrades less under tested synthetic attacks in point estimate (directional, not significant at seven events). OMI’s empirical lift is modest and regime-dependent (pooled 0.0037, not significant; it helps off-chain and multi-venue settings, not single-venue on-chain ones), and precision is low (about 33 false-positive windows per true-positive window at 10% recall). Within this early-warning setting, oracle manipulation is a weak evasion vector because the tested subset is empirically less sensitive to the evaluated perturbations.

Double counting in supply-chain carbon accounting can arise when an emission-related claim remains usable after splitting or integration. Existing systems can strengthen traceability, evidence integrity, or ex-post auditing without defining whether a consumed claim remains valid for reuse. We model this gap as a lifecycle-state consistency problem and present a three-tier framework compatible with Ethereum Request for Comments 1155 (ERC-1155), with three non-fungible token (NFT) lifecycle roles: parent NFT (P-NFT), child NFT (C-NFT), and integrated NFT (I-NFT). The execution-time control layer enforces quantity conservation, immediate parent retirement, and complete-set same-transaction consumption, rejecting violations before state commitment. I-NFT verification binds each integrated claim to its consumed input set through a compact header and issuance-transaction events. Functional validation shows that quantity inflation, parent reuse, partial integration, and consumed-child reuse revert with unchanged checked post-state, while a valid lifecycle passes consistency checks. Gas evaluation over shows near-linear growth: Split at $n=50$ uses 12.91 M gas, while $n=100$ uses 25.75 M and exceeds the current 16.78 M Ethereum transaction cap. Blockchain and ERC-1155 are deployment and representation choices rather than correctness mechanisms. The security claim is limited to on-chain lifecycle consistency; physical-world input authenticity remains external.