Notes onsecurity proof of digital signature scheme
QI Ya-ping, Liu Wen-hua, Yong Hong Yu · Computer Engineering and Applications Journal · 2007
Recently,Willy、Zhang and Yi proposed an identity-based strong designated verifier signature scheme(noted as WZY scheme) and gave the security proof of the scheme.Unfortunately,We find that their security proof is improper:in the proof of the unforgeability of the scheme,they supposed that the adversary has the secret key of the designated verifier.Under a simple assumption that the hash function is considered as an oracle that on each valid input known to the adversary beforehand produces a random value,a new proof that the unforgeability of WZY scheme relies on the Bilinear Diffie-Hellman Problem is given.