Hashing in MySQL

Password Hashing in MySQL

MySQL lists user accounts in the user table of the mysql database. Each MySQL account can be assigned a password, although the user table does not store the cleartext version of the password, but a hash value computed from it.

MySQL uses passwords in two phases of client/server communication:

When a client attempts to connect to the server, there is an initial authentication step in which the client must present a password that has a hash value matching the hash value stored in the user table for the account the client wants to use.

After the client connects, it can (if it has sufficient privileges) set or change the password hash for accounts listed in the user table. The client can do this by using the PASSWORD() function to generate a password hash, or by using a password-generating statement (CREATE USER, GRANT, or SET PASSWORD).

In other words, the server checks hash values during authentication when a client first attempts to connect. The server generates hash values if a connected client invokes the PASSWORD() function or uses a password-generating statement to set or change a password.

Password hashing methods in MySQL have the history described following. These changes are illustrated by changes in the result from the PASSWORD() function that computes password hash values and in the structure of theuser table where passwords are stored.

Example