A Forward Secure Ring Signature Scheme

Exposure of secret keys is fatal to the security of a signature scheme. Digital signature with forward security is proposed in order to reduce the loss arisen by the exposure of secret keys, in which even the attacker obtains the current secret key of some user illegally, he still can not forge the signature of the past time period. This is the first forward secure ring signature scheme which is based on the difficulty of quadratic root modulo composite problem and RSA problem.