Security Analysis of Two ID-based Ring Signature Schemes in Standard Model

Ring signature is the cryptographic primitive for signer's privacy protecttion. The ring signature scheme must meet some security requirements, such as unconditional anonymity, unforceability and so on. In this paper, the security analysis of two existed ID-based ring signature schemes in the standard model is made. The security analysis show that these two ring signature schemes cannot satisfy the unforgeabilty of ring signature. The corresponding forgery attack methods are given.