A New Highly Secure Directed Signature Scheme.

This paper presents a new directed signature scheme based on hybrid problems; factoring and discrete logarithm. The scheme allows only an intended verifier to verify the produced signature and provides a mechanism to prove the validity of the resulted signature to any third party whenever necessary. Up to now, the security of many existing directed signatures was based on a single hard problem like factoring, discrete logarithm or elliptic curve discrete logarithm and these schemes appear secure today but in a near future, if an adversary finds a solution of these hard problems then the schemes will no longer be secure. Thus, the newly directed signature is developed to provide greater security level than that any directed signature schemes since it is impossible for the adversary to solve the two hard problems simultaneously. [ABSTRACT FROM AUTHOR]