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.

The characteristic code has the following characteristics. First of all, it is irreversible. For example, I have a ciphertext like My Secret Language. After algorithm conversion, I got the MD5 code (B9944E9367D2e40DD1F0C4040D4 daaf7). Tell others this code, and others will know what your original text is according to this MD5 code.

In 2004, MD5 algorithm was proved to be unable to prevent collisions, so it is not suitable for security authentication, such as SSL public key authentication or digital signature.