Certificateless Proxy Signature and Its Extension to Blind Signature

Abstract

In traditional public key infrastructure (PKI), a trusted third party called certificate authority (CA) is required in order to assure the correctness of a user’s public key. ID-based cryptosystem solves this problem since a user’s public key is just its identity. However, it suffers the key escrow problem. In 2003, Al-Riyami and Paterson introduced the certificateless cryptosystem which inherits both the advantages of traditional cryptosystems and ID-based cryptosystems. That is, a certificateless cryptosystem doesn't require a certificate and it can solve the key escrow problem. In this paper, we introduce a certificateless proxy signature scheme. Proxy signature is useful in many applications. The advantage of our scheme is that it is very easy and very efficient to extend our scheme into a certificateless proxy blind signature scheme. We emphasize that this is the first work that successfully constructing a certificateless proxy signature scheme.