|
Trusted Computing Group believes that privacy protection is one of necessary elements of trusted computing systems, and users must have the rights to choose and control their private information. In 2003, to ensure the anonymity in authentication and resolve the problems of Privacy CA scheme, Trusted Computing Group issued DAA scheme. However, the DAA scheme is not very satisfactory in real systems for its spending too much time.In this paper, some special schemes which can be achieved anonymity, such as signature proxy signature schemes, blind signature schemes and group signature schemes, are studied. Then the background, the stage of development and the achieving mechanisms of DAA scheme are also studied. In the framework of DAA anonymous mechanism, the main method of reducing time expense is to shorten the length of parameters. But only to shorten the parameters length, will the security be decreased too. To shorten the length of parameters and guarantee the security and anonymity of new scheme, we may change the discrete logarithm problem into elliptic curves cryptosystem. However, DAA scheme is the scheme which is integrated by factoring integers and discrete logarithm problem, just changing the discrete logarithm problem into elliptic curves cryptosystems, will make the scheme unsafe. For these reasons, a new scheme has been offered. In the new scheme, factoring integers and discrete logarithm problem are discarded, and a new method was joined, so the requirements of the original scheme would be achieved by elliptic curves cryptosystem.Finally, we compares the new scheme with the original scheme on the security, the anonymity and the efficiency. In order to carry out the efficiency analysis, the new scheme and the original scheme are simulated. In the implementation, the operation of communication is omitted and a stand-alone version is carried out. In the simulation programs, the class of set-up for producing a public key, the class of Hash for constructing hash function, the class of TPM for implementing the functions of TPM, the class of host, the class of issuer, the class of verification, the class of daa, and the class of ecc are all constructed.Comparing with the original scheme, the new scheme does not decrease the safety and anonymity. At the same time, it improves efficiency by reducing the time expense.
|