A Study On Two Kinds Of Proxy Blind Signature Scheme

Cryptographic technique is the core of the Information security. In addition toproviding information encryption and decryption, cryptographic techniques alsoprovides identification of sources of information, and ensure information integrity andnon-repudiation functions. These three functions are realized by a digital signature.Depending on the practical needs, digital signature is divided into many differenttypes. Proxy blind signature is one of them. Proxy blind signature is a digital signaturethat combine the proxy signature with blind signature. Because the proxy blindsignature has advantage of both proxy signature and blind signature, their applicationscover a very wide range. Contents of this paper consist of following：1. First, we analysis the proxy blind signature scheme based on discrete logarithm[44]. We find out the scheme can not meet unforgeability. This paper proposes animprovement scheme on the basis of the original one. We give a proof of thecorrectness and unforgeability of the new scheme.2. Second, we analysis the certificateless proxy blind signature scheme [53]. Wefind out that the dishonest key generation center can change the system parametersin this signature scheme. And public key safety is not considered in algorithmsprocess. Eventually the scheme leds to malicious-but-passive KGC attacks andpublic key replacement attacks. This paper has made improvements in the detail.The new scheme can resist public key replacement attacks and malicious KGCattacks. And there is no change in the efficiency.