关键词: 基于证书的密码体制, 多代理签名, 双线性对, 公钥替换攻击, 随机预言机模型

Abstract: Certificate-based cryptosystem can not only reduce the high cost of public key management, but also solve the key escrow problem. Multi-proxy signature allows an original signer to delegate his signing rights to a proxy group, and only the cooperation of all signers in the proxy group can generate a valid proxy signature. This paper presents a new formal definition and a new security model of certificate-based multi-proxy signature, and proposes a concrete scheme without using bilinear pairings. Based on the discrete logarithm assumption, this paper proves the scheme to be unforgeable in the random oracle model. The efficiency analysis shows that the scheme has higher efficiency. At last, this paper gives the application examples.

Key words: certificate-based cryptosystem, multi-proxy signature, bilinear pairings, public key replacement attacks, random oracle model