A Generic Conversion from Proxy Signatures to Certificate-based Signatures

A Generic Conversion from Proxy Signatures to Certificate-based Signatures

The proxy signature (PS) and the certificate-based signature (CBS) are both popular cryptographic protocol. The former is a special signature which allows an entity to delegate his signing rights to another, while the later is another attractive cryptography primitive whose original motivation is to simplify certificate’s management and to eliminate key escrow problem. However, there is a drawback in the existing security model of PS, and there are something in common between the CBS and the PS. In the paper, we first analyze the drawback of the existing security model of PS. Secondly, we propose an improved security model for PS which is stronger than the existing one to overcome its drawback, new model allows an adversary of PS to issue both queries for different proxy signers but the same original signer. Thirdly, we proposed a new paradigm PS-2-CBS which is a generic conversion from an existing secure PS to a secure CBS after analyzed the relationship between the CBSs and the PSs. and prove that our PS-2-CBS is secure if the underlying PS is secure under improved security model of PS. Finally, an example of PS-2-CBS is gave.