Security Analysis of the Pomykala-Barabasz Scheme

Article type: Research Article

Authors: Li, Fagen | Hu, Yupu

Affiliations: School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan, P.R. China. E-mail: [email protected] | Key Laboratory of Computer Networks and Information Security, Xidian University, Xi'an 710071, Shaanxi, P.R. China

Abstract: In 2006, Pomykala and Barabasz [Fundamenta Informaticae 69 (2006) 411–425] proposed an elliptic curve based threshold proxy signature scheme which requires shorter cryptographic keys. They claimed that their scheme satisfies the secrecy, the proxy protected, the unforgeability, the non-repudiation, and the known signers. However, in this paper, we show that their scheme cannot achieve the proxy protected, the unforgeability and the non-repudiation by demonstrating a conspiracy attack. In this attack, any t malicious proxy signers can collusively impersonate some other proxy signers to generate proxy signatures.

Keywords: cryptography, proxy signature, threshold proxy signature, conspiracy attack

Journal: Fundamenta Informaticae, vol. 80, no. 4, pp. 453-459, 2007