MD5 algorithm Research (1)

Review
The full name of MD5 is message-digest algorithm 5 (Information-Digest algorithm), in the early 90 by MIT Laboratory for Computer and RSA Data Security Inc, Ronald L. Riv EST developed and developed by MD2, MD3 and MD4. Its role is to allow bulk information to be "compressed" into a confidential format (that is, to transform a byte string of any length into a long, large integer) before signing the private key with the digital signature software. Whether they are MD2, MD4, or MD5, they need to obtain a random length of information and produce a 128-bit summary of the information. Although the structures of these algorithms are more or less similar, the design of MD2 is completely different from MD4 and MD5 because MD2 is designed for 8-bit machines, while MD4 and MD5 are 32-bit computers. The descriptions of these three algorithms and the C language source code are described in detail in the Internet RFCs 1321 (http://www.ietf.org/rfc/rfc1321.txt), which is the most authoritative document by Ronald L. Rivest submitted to Ieft in August 1992.
Rivest developed a MD2 algorithm in 1989. In this algorithm, the data is first made to complement the information, so that the byte length of the information is 16 multiples. Then, with a 16-bit check and append to the end of the message. And the hash value is computed based on the newly generated information. Later, Rogier and Chauvaud found that if the test was omitted and a MD2 conflict would arise. The MD2 algorithm's encryption results are unique-there is no duplication.
In order to enhance the security of the algorithm, Rivest developed a MD4 algorithm in 1990. The MD4 algorithm also needs to fill the information to ensure that the byte length of the message plus 448 can be divisible by 512 (Information byte length mod 512 = 448). Then, a 64-bit binary representation of the initial length of information is added in. Information is processed into blocks of 512-bit damg?rd/merkle iterative structures, and each block is processed by three different steps. Den Boer and Bosselaers and others quickly discovered vulnerabilities in the first and third steps of the attack MD4 version. Dobbertin shows you how to use a common personal computer to find a conflict in a MD4 full version in a few minutes (this conflict is actually a vulnerability that will result in encryption of different content and possibly the same encrypted result). There is no doubt that MD4 was eliminated from the matter.
Although the MD4 algorithm has such a big loophole in security, it can not ignore the emergence of several kinds of information security encryption algorithms that have been developed since then. In addition to MD5, the more famous among them are SHA-1, RIPE-MD and Haval.
A year later, in 1991, Rivest developed a more technologically sophisticated MD5 algorithm. It adds the concept of "security-straps" (safety-belts) on the basis of MD4. Although MD5 is slightly slower than MD4, it is more secure. This algorithm is clearly composed of four and MD4 designs with a few different steps. In the MD5 algorithm, the size of the information-digest and the necessary conditions for filling are exactly the same as the MD4. Den Boer and Bosselaers have discovered a fake conflict (pseudo-collisions) in the MD5 algorithm, but there are no other encrypted results found.