Cryptanalysis Of Blue Midnight Wish Algorithm Of The Second Round Candidates Of The SHA-3

Cryptographic Hash function in modern cryptography occupy an important place, it can be an arbitrary length messages to fixed-length compression Hash value. Hash function the basic idea is the message digest as input a message such as a compact that used to uniquely identify the message. As the Hash function has a easy of computation, compressibility, preimage resistance, second-preimage resistance, collision resistance, so Hash functions are widely used in data integrity testing, digital signatures, message authentication, document verification, etc. Hash function is also a number of cryptographic algorithms and cryptographic protocol security, the basic prerequisite. Hash function is one of the most important uses for digital signatures. Hash function is due to have a wide range of applications, so Hash function design and analysis of the field of information security has become a hot issue. Differential analysis is currently the standard Hash function, the most effective methods of analysis. In recent years, for the analysis of Hash function has made a breakthrough. AS Prof. Xiaoyun Wang made in the Hash function analysis of the outstanding achievement, making the current standard Hash function MDx series and SHA series of the security is not longer able to meet actual requirements. Therefore, NIST in 2007 launched the Hash function is the collection of new standards activities, namely, SHA-3competition.As of October 31,2008 NIST received from all over the world organization or individual proposals submitted by 64 candidates. There are 51 algorithms in the first round of candidate and 14 algorithms in the second round of candidate. Currently the second of candidates is under way.BLUE MIDNIGHT WISH (BMW) hash function is the fastest among 14 algorithms in the second round of SHA-3 competition, therefore, their safety is also of concern, and this paper is on the BMW algorithm analysis and research. In this thesis, we use bit-tracing method and message modification to find different path of BMW-256 algorithm. Compression function of BMW algorithm is composed of three functions, in which the function f1 has two tweaked parameters, the sum of two parameters and should be equal to 16, when the first parameter value the greater the security of the whole algorithm will be more safety at the same time efficiency of the algorithm will fall. First, we will introduce bit-tracing method, then, let's take ExpandRounds1=0, ExpandRounds2=16, We call the parameters of such a value of the BMW-256 algorithm is a simplified edition of the BMW-256 algorithm; And then according to the recommendations of the original authors take ExpandRounds1=2, ExpandRounds2=14, We are the parameters of such a value of the BMW-256 algorithm is called a Original Edition of the BMW-256 algorithm.For simplified edition of the BMW-256 algorithm is to take the differential of message block of one word is 1, other words to 0, take the differential of initial value of one word is 1, other words to 0, the first zero-bits for the low in every word. Use Bit-tracking method can be found a differential path of simplified edition of the BMW-256 algorithm, the probability of the establishment of the differential path is 2-377, through message modification the probability of the differential path is 2-319. The same way, according to different initial differential, we can get the original edition BMW-256 algorithm for differential path, the probability of the establishment of the differential path is 2-468, through message modification the probability of the differential path is 2-402.As the BMW-256 algorithm is a wide pipe iterative structure, so our path is a distinguisher for the intermediate transformation of BMW-256 algorithm.