## Cryptology ePrint Archive: Report 2005/240

Attack on Okamoto et al.'s New Short Signature Schemes

Fangguo Zhang and Xiaofeng Chen

Abstract: We present an attack on a new short signature scheme from bilinear pairing proposed by Okamoto $et$ $al.$ at ITCC'05. We show that any one can derive the secret key of the signer from any two message-signature pairs and so can forge the signer's signature for any message. This means the scheme is totally broken.

Category / Keywords: Short Signature, Bilinear Pairing, Attack

Publication Info: 2005 China National Computer Conference