Certificateless Multisignature And Certificateless Blind Signature

Certificateless public key cryptology is firstly proposed by Al-Rayami and Paterson in Asiacrypt 2003, which is a new paradigm between traditional certificate-based public key cryptology and identity-based public key cryptology. Contrary to traditional certificate-based cryptosystem, the new paradigm does not need certificate to ensure the authentication of user's public key, so it overcomes the problem of certificate management; Different to identity-based cryptosystem, the new paradigm only needs a semi-trusted third party, so it does not exist the problem of inherent key escrow.Multisignature is introduced by Irakura et. in 1983. Multisignature allows multi- signers to cooperate to generate one signature for some message, and any one can verify the signature. It can decrease the total length of signatures and the cost of verification.Blind signature is proposed by Chaum in Crypto 1982. The signature scheme can make user obtain a valid signature without knowing the signed message and the final signature. It has been widely used in electronic voting and electronic cash system.Combining the concept of certificateless signature with multisignatue and blind signature, this paper proposes the new concepts of certificateless multisignature and blind signature, gives the according formal definition and security requirements, then constructs the concrete certificateless multisignature scheme and certificateless blind signature scheme. Finally under the random oracle model, the paper analyzes the security of the proposed schemes.