Attack on Han et al.'s ID-based confirmer (undeniable) signature at ACM-EC'03

At the fourth ACM conference on electronic commerce (EC'03), S. Han, K.Y. Yeung and J. Wang proposed an ID-based confirmer signature scheme using pairings (actually, this is an ID-based undeniable signature scheme). However, in this paper, we will show that this signature scheme is not secure. The signer can deny any signature, even this signature is his valid signature and any one can forge a valid confirmer signature of a signer with identity ID on an arbitrary message and confirm this signature to the verifier. Key words Confirmer signature, Undeniable signature, Attack, Bilinear pairings, ID-based cryptography.

• Type: Journal
• Year: 2005
• Where: AMC
• Authors: Fangguo Zhang, Reihaneh Safavi-Naini, Willy Susilo
• Keywords: AMC 2005, Confirmer Signature, Signature, Signature Scheme