Abstract
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In Asiacrypt 2003, the concept of universal designated
verifier signature (UDVS) was introduced by
Steinfeld, Bull, Wang and Pieprzyk. In the new paradigm,
any signature holder (not necessarily the signer) can designate
the publicly verifiable signature to any desired designated
verifier (using the verifierÿs public key), such that only
the designated verifier can believe that the signature holder
does have a valid publicly verifiable signature, and hence,
believes that the signer has signed the message. Any other
third party cannot believe this fact because this verifier can
use his secret key to create a valid UDVS which is designated
to himself. In ACNS 2005, Zhang, Furukawa and Imai
proposed the first UDVS scheme without random oracles. In
this paper,we give a security analysis to the scheme of Zhang
et al. and propose a novel UDVS scheme without random
oracles based on Watersÿ signature scheme, and prove that
our scheme i