Abstract: The security of the bidirectional blind proxy re-signature scheme proposed by Deng et al. (DENG Y Q, DU M H, YOU Z L, 〖WTBX〗et al.〖WTBZ〗 A blind proxy re-signatures scheme based on standard model [J]. Journal of Electronics and Information Technology, 2010, 32(5): 1119-1223) was analyzed, and the scheme was found insecure. Meanwhile, a forgery attack on this scheme was given, in which the delegatee could produce the valid signature of the delegator without the help of the proxy. To overcome the weakness of this scheme, an improved blind proxy re-signature scheme was proposed, which was proved secure in the standard model. It can efficiently resist the forgery attack. The delegatee and the proxy can not obtain the contents of the message to be signed in order to better protect the privacy of the message. The proposed scheme is blind, bidirectional, multi-useful, transparent and key optimal.

Key words: bidirectionally blind proxy re-signature, multi-use, blindness, standard model, provable security

摘要： 分析了Deng等(DENG Y Q, DU M H, YOU Z L, et al. A blind proxy re-signatures scheme based on standard model [J]. Journal of Electronics and Information Technology, 2010, 32(5): 1119-1223)提出的双向盲代理重签名方案，发现该方案是不安全的，并给出了一种伪造攻击，受托者不需要与代理者合谋就能成功伪造委托者的签名。为了克服该方案存在的安全缺陷，提出了一个在标准模型下可证安全的双向盲代理重签名方案，可以有效地抵抗这类伪造攻击，并且受托者和代理者都无法获知所签消息的内容，能够更好地保护消息的隐私。分析结果表明，改进的新方案具有盲性、双向性、多用性、透明性和密钥最优性。

关键词: 双向盲代理重签名, 多用性, 盲性, 标准模型, 可证明安全