A Non-delegatable Strong Designated Verifier Signature without Random Oracles

We propose a scheme for non-delegatable strong designated verifier signature. The scheme is based on pairings, and utilizes an OR proof technique and a method of ensuring the integrity of a signature. In a standard model, the unforgeability property of the scheme is reducible to a computational Co-Diffie-Hellman problem. The scheme is perfect non-transferable, and its properties of privacy of signer´s identity and non-delegatability are reducible to the correctness of two variants of a knowledge of exponent assumption.