We propose a convertible undeniable signature scheme without random oracles. Our construction is based on the Waters signatures proposed in Eurocrypt 2005. The security of our scheme is based on the CDH and the decision linear assumption. Comparing only the part of undeniable signatures, our scheme uses more standard assumptions than the existing undeniable signatures without random oracles due to Laguillaumie and Vergnaud.
Tsz Hon Yuen, Man Ho Au, Joseph K. Liu, Willy Susi