Threshold Proxy Signature Scheme with Strong Real-Time Efficiency

The threshold proxy signature scheme with strong real-time efficiency is proposed based on a trapdoor hash function and the sharing secret technology. In the scheme, the procedure of generating threshold proxy signature is performed in two phases. The off-line phase generates a threshold proxy pre-signature before the message to be signed is even known. The pre-signature is independent of the particular message to be signed and is stored for future in the on-line phase. While on-line phase generates quickly a threshold proxy signature using the pre-signature once the message to be signed is presented. The on-line phase is typically very fast and strong real-time efficiency since it only needs a few modular additions and multiplications and one round of communication among proxy signers. Furthermore, the scheme not only has strong real-time efficiency, but also withstands the conspiracy attack existed in the previous schemes and requires no trusted third party. The scheme is particularly useful for requiring the strong real-time efficiency and fully distributed networks such as electric wallet or smart cards etc.