Anonymous Agent Signer Based On Quadratic Residual

With the globalization of information, security has been the most concerned issues. In the process of communication, we should ensure confidentiality and authentication of the message at the same time. The traditional approach is to sign the message first and then encrypt it.Signcryption realizes the process of signature and encryption at the same time. The cost of signcryption is lower than "sign and encrypt". Traditional signcrypton don’t work when a signcrypter cannot give a signcryption due to travel or other reasons. Carnage proposed the notion of proxy signcryption to solve the problem. It means a signcrypter can authorize his right to the proxy signcrypter. Most existing proxy signcryption schemes do not take the anonymity into consideration because the entrustment information must include the information about the original signcrypter and the proxy signcrypter and other limitations to verify the legitimacy of a proxy signcryption.In some special occasions, the original signcrypter do not want the verifier to get the identity of the proxy signcrypter. In electronic trading, user A will warrant his account to user B,but user A does not want the bank to track information of the user B. There are similar scenarios in real life, such as "close to pay" on Taobao. On such occasions, we must make the proxy signcrypter hided.Focusing on these problems, the innovation points of this article are as follows:·Through the analysis of existing schemes, we construct a proxy signcryption scheme with anonymous proxy signcrypter combined with the advantages of the existing scheme. Verifier cannot obtain the identity of proxy signcrypter from signcryption without the help of original signcrypter. When dispute arise, the verifier can ask the original signcrypter to uncover the identity of the proxy signcrypter.·This thesis constructs an anonymous proxy signcrypter scheme based on quadratic residue. The scheme has the features of public verifiability, anonymity, unforge ability under adaptively chosen message attack and indistinguish ability under adaptive chosen ciphertext attack. Moreover, it can resist authentication attacks. In addition, it is more effective in computation compared with other scheme.