On the Security of a Certificateless Strong Designated Verifier Signature Scheme

Recently, Chen et al. proposed the first non-delegatable certificateless strong designated verifier signature scheme and claimed that their scheme achieves all security requirements. However, in this paper, we disprove their claim and present a concrete attack which shows that their proposed scheme is forgeable. More precisely, we show that there exist adversaries who are able to forge any signer s signature for any designated verifier on any message of his choice.

Keywords:

Certificateless cryptography , Cryptanalysis , Designated verifier signature , Non-delegatability