An ID-based Server-aided Verification Short Signature Scheme Avoid Key Escrow *

A server-aided verification signature, some complex computation for verification of a signature is carried out by a server. Thus, it is very suitable for low-power computation devices. In this paper, by combining ID-based cryptography and server-aided verification signature, we propose an ID-based server-aided verification signature scheme, and give two SA-Verifying ways to realize server-aided verification. The scheme has the following advantages: (1) short signature length; (2) avoiding key escrow problem of ID-base cryptography; (3) less computational cost for a verifier. After we formally define the existential unforgeability security model of ID-based server-aided verification signature to capture the attack of the dishonest signer and the dishonest PKG, a detail instance is given. And we show that our scheme is secure in the random oracle model. To the best of our knowledge, it is the first ID-based server-aided signature scheme. By comparison with SAV-BLS, we show that our schemes have the same signature length 160bits and the approximately computational cost. Especially, the verifier doesn’t require pairing operator in the second SA-verifying way.