Security Analysis and Performance Evaluation of Certificateless proxy Re-Encryption for Blockchain Applications

Abstract

Secure data sharing is a fundamental requirement for
blockchain-based applications, particularly in decentralized
environments where users must exchange encrypted information
without relying on centralized authorities. Proxy Re-Encryption
(PRE) is a cryptographic technique that enables a semi-trusted proxy
to transform ciphertext encrypted for one user into ciphertext
decryptable by another user without revealing the underlying
plaintext. However, traditional PRE schemes often rely on Public Key
Infrastructure (PKI) or identity-based cryptography, which introduces
challenges such as certificate management overhead and key-escrow
problems. Certificateless Proxy Re-Encryption (CL-PRE) has
emerged as a promising alternative that eliminates certificate
management while mitigating key escrow issues.
Despite these advantages, existing CL-PRE schemes suffer from
security vulnerabilities and performance limitations that hinder their
practical deployment in blockchain environments. This paper presents
a comprehensive security analysis and performance evaluation of CLPRE
schemes for blockchain applications. The primary contribution
is the identification of a critical public key replacement attack against
Wang et al.’s CL-PRE scheme. In this attack model, a Type-I
adversary replaces legitimate public keys with maliciously generated
keys, enabling ciphertext decryption without access to the original
private keys and thereby compromising message confidentiality and
violating IND-CCA security guarantees.
In addition to the security analysis, this work conducts a systematic
performance evaluation of pairing-free proxy re-encryption schemes
tailored for blockchain environments. Extensive benchmarking of
three PRE schemes implemented in Go demonstrates that the self-
PRE scheme provides stronger security guarantees but incurs
approximately 13.7% higher execution time compared to
certificateless approaches. To mitigate the identified vulnerabilities,
this research proposes a secure CL-PRE framework with enhanced
validation mechanisms and strengthened public key verification.
Furthermore, the proposed framework is implemented on the
Ethereum platform to evaluate its practical feasibility in decentralized
systems. Experimental results show that the implementation reduces
on-chain storage requirements by approximately 40%, improves
computational efficiency by
...
14.1% compared to existing secure schemes, and reduces smart
contract gas costs by 14.3% while maintaining provable security
properties.
The findings establish important security benchmarks and
performance guidelines for blockchain developers, emphasizing the
importance of rigorous cryptographic analysis when designing
decentralized access control and secure data-sharing mechanisms.