Research On Irreversible Transformation Of Fingerprint Safety Authentication

Traditional biometric feature recognition technology is becoming more and more mature these days, take fingerprint recognition for example, it has completely reached the practical requirements no only in accuracy but also in speed. Normally biometric feature recognition is treated as the final solution of identity recognition, it has been widely respected and applied in fields of public security, banking, e-commerce. However, with the rapid growth of secure requirements, the identity should be digital and recessive; and people still haven’t pay enough attention to the security of the biometric template itself. Some biological features(fingerprint, for example) won’t change in all life-time, which means once they are lost, the damage is irreversible. These security threats have severely restricted the further development of the identity authentication technology which based on biometric feature recognition. As one of classic biometric features, more and more researchers have focus on study of security on fingerprint feature. Therefore, fingerprint security recognition technology which combines fingerprint feature recognition with cryptography emerges as the times require.Biometric feature recognition technology is relatively mature and it gets a very wide application foreground. Although it has made great progress about fingerprint security recognition technology in recent years, most of them still can’t prevent all types of attacks that listed in the thesis. In order to eliminate the anxious about the safety of biometric feature recognition and promote the further development of biometric feature recognition technology, research of how to protect biometric feature templates which includes fingerprint becomes one of the hot issues. Fingerprint security recognition technology is studied from several aspects respectively, such as the improvement of hash compression function, the improvement of hash iterative structure, the design of fingerprint feature information which bases on the relativity of minutiae, the design of irreversible transformation, the construction of fingerprint encryption and decryption. The main work of this thesis is listed as follows:(1)The research progress of fingerprint security recognition technology is surveyed, the research status and development trend are summarized, the research and application value are evaluated, the security requirements of this technology are investigated, on the basis of the characteristics of the technology, security goals such as irreversibility, local smoothness, cancelability are treated as the forefront, the improvement of irreversibility of transform technology by applying irreversible transformation which is constructed by improved hash function, local smoothness of authentication is satisfied by using boundary box matching technology, the realization of the revocation of fingerprint template of authentication technology by applying the reset of security parameter, as well, the relevant cryptography foundation and fingerprint security authentification technology are summarized.(2)In this thesis, classic hash function SHA1 and SHA2 have been studied and improved respectively, improved SHA1 and SHA2 algorithms which can resist differential attack have been designed by analyzing the essence of differential attack, SHA1 algorithm has been improved in four aspects: First, the initial value of register is optimized, second, the constant parameters of addition is optimized, third, the logical function is improved, fourth, the compression function is improved. In addition,SHA2 algorithm is improved in two aspects: one is the compression function, the other is extension algorithm of messages. Property of avalanche, irreversibility and collision resistance in improved algorithm are proved through security analysis.(3)Starting with various attacks which MD structure of classical iteration structure of traditional hash function is suffered, many kinds of attacks are introduced and analyzed. The MD iteration structure is improved; two safety parameters are added in the process of iteration, improving the message padding scheme and designing double-serial iteration structure, since the link variables in the process of calculation are influenced by more message blocks, therefore, this structure not only can avoid traditional secondary collision attack, multi-collision attack, second-preimage attack to long messages, but also accelerate the avalanche of message spreading. its efficiency is proved to be equal to double–pipe structure while improving the safety of MD iteration structure by improvement.(4)Researching fingerprint security authentication scheme which bases on irreversible function, analyzing the flaws of feature matching scheme which is based on fingerprint minutiae, designing fingerprint features which bases on the relativity of minutiae information, during the matching process, there is no need to execute pre-alignment operation of two fingerprint images, therefore, the matching time is saved, errors that come from pre-alignment operation are also eliminated. Later, fingerprint features that based on Delaunay triangle are also designed. Fingerprint features which are constructed by combining Delaunay triangle with Delaunay quadrangle not only solve the problem of alignment, but also improve GAR and matching speed. It solved the problem of low matching speed of large-scale fingerprint database. Then a one-way irreversible transformation function is constructed by using the improved hash function which is designed previously. In the analysis of security, we can see that the constructed irreversible transformation has irreversibility, local smoothness, transformation and distinctiveness, fingerprint encryption and decryption scheme are constructed on this basis. The result shows that the scheme has better FAR and FRR.With the widespread use of fingerprint recognition and other biometric feature recognition technology, a feature template protection scheme which is based on cryptography structure is required, so that it can meet the security requirements for privacy protection which in the process of identity authentication. Since the fingerprint will not change in people’s all life-time and the mass data of fingerprint database, research of secure fingerprint authentication are severely challenged, especially on strict secure requirements such as GAR, FRR and authentication speed. Facing the challenges, irreversible transformation technology for fingerprint security authentication technology has been researched the need of security requirements, and then threat of property security on account of privacy information leakage can be avoided, people can enjoy the great convenience that comes from fingerprint or other biometric feature recognition technology in the process of identity authentication.