# An Improved Digital Signature Protocol to Multi-User Broadcast Authentication Based on Elliptic Curve Cryptography in Wireless Sensor Networks (WSNs)

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## Abstract

**:**

## 1. Introduction

## 2. Related Works

#### Design Goal

## 3. Preliminary Material

#### Binary Elliptic Curve Cryptography

^{m}) by two parameters, b ≠ 0 and a, b ∈ GF(2

^{m}), where m is a positive integer. An elliptic curve over GF(2

^{m}) is the point at infinity, denoted as O, as well as all points (x, y) with the proviso that x, y ∈ GF(2

^{m}) and also satisfies Equation (1).

^{m}), then the main points, in the encryption system, are the following:

- $O+O=O.$
- $O+P=P$ for all values of $P=\left(x,y\right)\in Z$.
- $P+Q=O$ for all values of $P=\left(x,y\right)\in Z$ and $Q=\left(x,-x-y\right)\text{}\in Z$.
- Point addition operation in an Elliptic Curve

_{1}, y

_{1}) on the elliptic curve to obtain another point L = (x

_{2}, y

_{2}) = 2P on the same elliptic curve [27,28].

## 4. Adversary Model

**Active Attack**

**Compromise Attack**

**Denial-of-Service Attack (DoS)**

**User Anonymity**

## 5. An Improved Proposed Protocol Based on Elliptic Curve Cryptography

#### 5.1. Pre-Distribution Phase

_{x},G

_{y}) on the elliptic curve with the proviso that G is a finite point on the elliptic curve and also has the largest order n.

#### 5.2. Key Generation Phase

#### 5.3. Signed Production Phase

#### 5.4. Signature Verification Phase

## 6. Proposed Scheme for Broadcast Authentication in Wireless Sensor Network

- (1)
**System initialization phase:**Before deploying sensor nodes, each of them is preloaded with system parameters such as elliptic curve parameters and public key of sink and also $<{Q}_{i},I{D}_{i}>$ for all users. ID denotes the identity and Q denotes the public key of a user.- (2)
**User addition:**A user chooses a unique identifier ID and sends it to the sink. Next, the sink generates a public key and private key $<{Q}_{i},{d}_{i}>$ in the key generation phase of the proposed protocol for $use{r}_{i}$. The sink delivers $<{Q}_{i},{d}_{i}>$ for $use{r}_{i}$ and also broadcasts $<{Q}_{i},I{D}_{i}>$ to sensor networks using secure channel.- (3)
**Broadcast authentication message**: In order to broadcast an authenticated message to the sensor networks, the $use{r}_{i}$ with identifier $I{D}_{i}$ sends the following message:$<M,{T}_{i},Sig(M,{T}_{i},I{D}_{i}),{Q}_{i}>$, where M denotes the message, ${T}_{i}$ denotes the timestamp, and $Sig(M,{T}_{i},I{D}_{i})$ is the signature generation phase of proposed protocol over $(M,{T}_{i},I{D}_{i})$. When the message is received, the sensor node takes the following action:- (a)
- Check whether the timestamp ${T}_{i}$ is fresh.
- (b)
- Verify the received signature using the proposed protocol if ${T}_{i}$ is fresh, otherwise drop the message.
- (c)
- If the signature verification on the received message succeeds, then disseminate the authenticated message to the adjacent sensor nodes, otherwise reject the message and report the potential attack to the sink immediately.

- (4)
**User revocation:**When a user is compromised by an attacker, the sink may revoke her/him from the WSN. As a result, in order to revoke a user, the sink broadcasts a revoke message to the sensor network. Sensor nodes listen to the sink’s broadcast and remove the ID and the public key of the compromised user. After that, if each sensor node that received the broadcast message is from the same user, it will drop it and report the potential attack to the sink.

- First, the attacker creates a fake message $\widehat{m}$.
- In this step, the potential attacker calculates ${R}_{result}=hash\left(m\right)\xf7hash\left(\widehat{m}\right)$ (if $hash\left(m\right)$ can be divided by $hash(\widehat{m})$).
- Also, the attacker calculates the ${X}^{\prime}={R}_{result}\times X$.
- Finally, the attacker uses $(\widehat{X},s)$ as the signature of the message $\widehat{m}$ and broadcasts the fake package $\left({X}^{\prime},s,\widehat{m}\right)$ into wireless sensor networks.
- Finally, the intended victim receives the fake package $\left({X}^{\prime},s,\widehat{m}\right)$ and calculates and compares the values $u={e}^{\ast}{X}^{\prime}+Q$ and $v=s\times G$ to each other. Since $v$ and $u$ are equal, as a result, the intended victim approves the fake message $\widehat{m}$ as a valid message.

#### 6.1. When Output $e$ mod ${e}^{\ast}$ = 0 with the Condition that $e>{e}^{\ast}$

#### 6.2. When Output ${e}^{\ast}$ mod $e$ = 0 with the Condition that $e<{e}^{\ast}$

#### 6.3. When Output $e$ mod ${e}^{\ast}\ne $ 0 with the Condition that $e>{e}^{\ast}$

#### 6.4. When Output ${e}^{\ast}$ mod $e$ ≠ 0 with the Condition that $e<{e}^{\ast}$

**Signature Generation**

- Selects an integer number k randomly in the range of 1 to n − 1, where $k\ne d$.
- Computes $F=kG$.
- Extracts the integer $e$ from the message $m$ using a hash-function operation, $e=hash\left(m\right)$ and sets the most significant bit (MSB) of $e$ to 1.
- Computes $s=\left(kre+d\right)modn$.
- Finally, the generated signature for the message $m$ by the signer $A$ is $\left(s,F,X\right)$.

**Signature Verification**

- Computes ${e}^{\ast}=hash\left(m\right)$ and sets the most significant bit (MSB) of ${e}^{\ast}$ to 1.
- Computes $v=s\times G$ and u=${e}^{\ast}$X + Q.

**1**1111111 mod

**1**1111111 is 0. It means that the content of message $m$ is not altered. Moreover, this example can be extended to N-bits. As a result, we can easily prevent the mentioned attack.

## 7. Security Analysis

#### 7.1. Security Analysis of Proposed Protocol

#### 7.2. Security Strength of Proposed Scheme

**Active Attack**

**Compromise Attack**

**Denial-of-Service Attack (DoS)**

**User Anonymity**

## 8. Results and Evaluations

- T
_{Mul}: time complexity of implementing a modular multiplication. - T
_{Add}: time complexity for implementing a modular add operation. - T
_{EC Mul}: time complexity for implementation of multiplying points in an elliptic curve. - T
_{EC Add}: time complexity to implement the sum of two points of the elliptic curves. - T
_{Inv}: time complexity for executing a reverse acting modular. - T
_{Hash}: time complexity to run a one-way hash function.

- The Cao et al.’s time complexity scheme equals ${T}_{excute}\cong 30{T}_{Mul}+1000\left(87.24{T}_{Mul}\right)=87270{T}_{Mul}$.
- The Ren et al.’s time complexity scheme equals ${T}_{excute}\cong 31{T}_{Mul}+1000\left(60.12{T}_{Mul}\right)=60151{T}_{Mul}$.
- Time complexity of our proposed scheme equals ${T}_{excute}\cong 60{T}_{Mul}+1000\left(58.12{T}_{Mul}\right)=58180{T}_{Mul}$.

## 9. Conclusions

## Author Contributions

## Conflicts of Interest

## References

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Time Complexity of an Operation Unit | Time Complexity Based on Modular Multiplication |
---|---|

${\mathit{T}}_{\mathit{E}\mathit{C}\_\mathit{M}\mathit{u}\mathit{l}}$ | $\mathbf{29}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$ |

${\mathit{T}}_{\mathit{E}\mathit{C}\_\mathit{A}\mathit{d}\mathit{d}}$ | $\mathbf{0.12}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$ |

${\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}$ | $\mathbf{0.073}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$ |

${\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}$ | Negligible |

${\mathit{T}}_{\mathit{M}\mathit{i}\mathit{n}\mathit{u}\mathit{s}}$ | Negligible |

${\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | Negligible |

Various Protocols | Signature Generation Phase | Computation Complexity Based on ${\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}$ | Signature Verification Phase | Computation Complexity Based on ${\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}$ |
---|---|---|---|---|

Rabah, 2005, [37] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}$ | $\mathbf{31.073}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{3}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{87.12}{\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ |

ECDSA Johnson et al., 2001, [34] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}$ | $\mathbf{31.073}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}$ | $\mathbf{60.193}{\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ |

Chung et al., 2007, [38] | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{60.12}{\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{3}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{87.24}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

Nikooghadam et al., 2008, [35] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{31}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{59.12}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

Hu Junru, 2011, [39] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}$ | $\mathbf{31.073}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{60.12}{\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ |

TR0311, 2012, [40] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{M}\mathit{i}\mathit{n}\mathit{u}\mathit{s}}$ | $\mathbf{30}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{M}\mathit{i}\mathit{n}\mathit{u}\mathit{s}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{I}\mathit{n}\mathit{v}}$ | $\mathbf{60.193}{\mathit{T}}_{\mathit{M}\mathit{U}\mathit{L}}+{\mathit{T}}_{\mathit{H}\mathit{a}\mathit{s}\mathit{h}}$ |

Our proposed protocol | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{30}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{58.12}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

Schemes | Signature Generation Phase | Time Complexity in ${\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$ | Signature Verification Phase | Time Complexity in ${\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$ |
---|---|---|---|---|

Cao et al.’s scheme [18] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$$+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{30}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{3}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{87.24}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

Ren et al.’s scheme [8] | ${\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{i}\mathit{n}\mathit{v}}$ | $\mathbf{31.073}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+\mathbf{2}{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}$$+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}+{\mathit{T}}_{\mathit{i}\mathit{n}\mathit{v}}$ | $\mathbf{60.193}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

Our proposed scheme | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+\mathbf{2}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}$$+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{60}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{A}\mathit{d}\mathit{d}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{2}{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{E}\mathit{C}-\mathit{A}\mathit{d}\mathit{d}}$$+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ | $\mathbf{58.12}{\mathit{T}}_{\mathit{M}\mathit{u}\mathit{l}}+{\mathit{T}}_{\mathit{h}\mathit{a}\mathit{s}\mathit{h}}$ |

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**MDPI and ACS Style**

Bashirpour, H.; Bashirpour, S.; Shamshirband, S.; Chronopoulos, A.T. An Improved Digital Signature Protocol to Multi-User Broadcast Authentication Based on Elliptic Curve Cryptography in Wireless Sensor Networks (WSNs). *Math. Comput. Appl.* **2018**, *23*, 17.
https://doi.org/10.3390/mca23020017

**AMA Style**

Bashirpour H, Bashirpour S, Shamshirband S, Chronopoulos AT. An Improved Digital Signature Protocol to Multi-User Broadcast Authentication Based on Elliptic Curve Cryptography in Wireless Sensor Networks (WSNs). *Mathematical and Computational Applications*. 2018; 23(2):17.
https://doi.org/10.3390/mca23020017

**Chicago/Turabian Style**

Bashirpour, Hamed, Saman Bashirpour, Shahaboddin Shamshirband, and Anthony T. Chronopoulos. 2018. "An Improved Digital Signature Protocol to Multi-User Broadcast Authentication Based on Elliptic Curve Cryptography in Wireless Sensor Networks (WSNs)" *Mathematical and Computational Applications* 23, no. 2: 17.
https://doi.org/10.3390/mca23020017