The Theoretical Research Of Message Authentications Codes

Message authentication code (mac) is an authentication scheme based on symmetrical cryptographic system, which provides a cryptographic scheme to protect data integrity and source authentication during communication over an open network. Research on mac has been a hot topic in modern cryptography.This dissertation studies on the analysis and design of mac.We obtain the main results as follows:1. Analysis the construction of xor-mac based on the block cipher, give a simple security proof of xor-mac based on information theory using shared random funciton model. Being splited into two parts:a pseudo-random funtion and a universal hash, xor-mac is can be regarded as a kind of carter-wegman mac by adopting a new method that applies a pseudo-random function directly to the output of a universal hash family. We point out that it is insecurity when pmac operates in two or more block cipher modes using the same keys, although pmac is provable security generically under the traditional attack models.2. Design a novel hbmac against related-key attacks using hash function and block cipher as basic modules. To avoid the vulnerabilities of hmac both to related-key attack and in multi-user environment,we modify hmac and build hbmac.Security proof for hbmac has been given on the basic assumptions that block cipher is pseudo-random permutation and the compression function used by hash function is a pseudo-random one, which uses the shared random model. Realization of hbmac and hmac algorithm is introduced. A contrastive analysis on the quality and efficiency of these two algorithms based on some typical data is proposed.3. Design a new homomorphic message authentication code (hommac) built on block cipher by combining the property of linear hash function using the idea form carter and wegman.An elegant and simple proofs-of-retrievability scheme is construced with the above hommac.In this scheme,the cost of computation and key management can be reduced using not many keys and complex setup course but a single key and a single state value.Futhermore,the proofs-of-retrievability scheme has its simplest form,which obtain the state value by cutting the input intelligently.4. The defects of existing spacemac, tracemac and hommac based on the linear map are pointed out.We present comprehensive analysis on tracemac and point out tracemac has inherent flaw so that adversary can make a forgery of message easilly in its scheme.To avoid this problem, people should take some measures given by this paper to improve security.And, an generic method to construct hommac is proposed.5. From the security model of hommac, a new carter-wegman hommac based on polynomial hash function is designed.The domain of this hommac algorithm is finite field which can make the security bound of scheme negligible.Meantime, by cutting down on the amount of key, using a single key, key storage and key distribution are easy.This hommac scheme has a common encoding efficiency and it achieves a rapid implementation by lookup tables and rapid calculation in finite field,which can be used online.