MD5 was designed by American cryptographer Ronald Linn Rivest and published in 1992 to replace MD4 algorithm. The program of this algorithm is standardized in RFC 132 1 standard.
After 1996, this algorithm has been proved to be weak and can be cracked. For data requiring high security, experts generally recommend using other algorithms, such as SHA-2. 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.
Used for password management
When we need to save some password information for identity confirmation, if the password information is directly stored in the database in plain code without any security measures, the system administrator can easily obtain the original password information, and once this information is leaked, the password will be easily cracked.
In order to increase security, it is necessary to encrypt the information that needs to be kept secret in the database, so that even if someone gets the whole database, the original password information cannot be obtained without decryption algorithm. MD5 algorithm can solve this problem well, because it can calculate the input string of any length and get the output of fixed length, and the premise is that the plaintext is the same.
We can only wait for the same ciphertext, and this algorithm is irreversible. Even if the encrypted ciphertext is obtained, it is impossible to calculate the plaintext by decryption algorithm.