摘要：

条件隐私保护认证(CPPA)是一种车载自组网(VANET)中支持安全通信的有效途径。针对VANET中消息认证低效以及数据隐私存在敌手威胁的问题, 提出基于区块链的轻量级CPPA方案。该方案在消息验证过程中采用改进的基于椭圆曲线加密的非交互式Schnorr签名算法, 避免使用耗时的密码学操作; 采用实体自行生成的短假名进行匿名通信, 系统架构引入联盟区块链, 在消息验证过程中利用智能合约技术自动验证发送者身份, 减少了方案的通信开销。安全性分析结果表明, 在随机预言模型(ROM)中, 提出的方案在自适应选择消息攻击下具有抗伪造的安全性, 且满足条件隐私保护要求。通过MIRACL密码学库测量了提出的方案和现有CPPA方案使用密码学操作的执行时间, 并运用Hyperledger Caliper评估了区块链测试网络的交易延迟和吞吐量。实验结果表明, 提出方案在签名生成和单条消息验证阶段的计算开销和通信开销均达到轻量级, 且有效支持批量消息验证。

关键词: 车载自组网, 条件隐私保护, 联盟区块链, Schnorr签名, 随机预言模型

Abstract:

Conditional Privacy-Preserving Authentication (CPPA) effectively supports secure communication in Vehicular Ad-hoc Network (VANET). To address the issues of inefficient message authentication and adversarial threats to data privacy in VANETs, a lightweight blockchain-based CPPA scheme is proposed. The proposed scheme utilizes an improved noninteractive Schnorr signature algorithm based on elliptic curve cryptography in the message verification phase, which avoids time-consuming cryptographic operations. The scheme employs entity-generated short pseudonyms for anonymous communication and introduces a consortium blockchain into the system architecture. The sender's identity is automatically verified during the message verification process using smart contract technology, thereby reducing the communication overhead of the scheme. Security analysis shows that the proposed scheme is secure against forgery under an adaptive chosen-message attack in the Random Oracle Model (ROM) while satisfying the requirements of conditional privacy preservation. Performance analysis measures the execution time of the proposed scheme and the existing CPPA scheme using cryptographic operations with the MIRACL cryptographic library. A Hyperledger Caliper is used to evaluate the transaction latency and throughput of the blockchain test network. The results demonstrate that the proposed scheme achieves lightweight computation and communication overhead in the signature generation and single-message verification phases and effectively supports batch message verification.

Key words: Vehicular Ad-hoc Network (VANET), conditional privacy-preserving, consortium blockchain, Schnorr signature, Random Oracle Model (ROM)