MD5 is a widely used hash function in the field of computer security, which is used to protect the integrity of messages. The file number of this algorithm is RFC1321(R. Riverst, Computer Science Laboratory of MIT and RSA Data Security Company, April 1992).
MD5 algorithm has the following characteristics:
1. Compressibility: For data with any length, the length of the calculated MD5 value is fixed.
2. Easy calculation: It is easy to calculate the MD5 value from the original data.
3. Anti-modification: any modification to the original data, even if only 1 byte is modified, the MD5 values obtained are quite different.
4. Weak anti-collision: knowing the original data and its MD5 value, it is difficult to find a data with the same MD5 value (that is, forged data).
5. Strong anti-conflict: It is difficult to find two different data and make them have the same MD5 value.
Extended data:
The simple description of MD5 algorithm can be as follows: MD5 processes the input information in 5 12 bit packets, and each packet is divided into 16 32-bit packets. After a series of processing, the output of the algorithm consists of four 32-bit packets, and concatenating these four 32-bit packets will generate a hash value of 128 bits.
Message summary 5
199 1 year, Rivest developed a more mature md5 algorithm. It adds the concept of "safety belt" on the basis of MD4. Although MD5 is more complicated than MD4, it is more secure.
This algorithm obviously consists of four steps, which is slightly different from MD4 design. In MD5 algorithm, the necessary conditions for the size and filling of information digest are exactly the same as MD4. Den boer and Bosselaers have discovered the pseudo-collision in MD5 algorithm, but there are no other discovered encryption results.
Reference: Baidu Encyclopedia -MD5