The validate_password plugin (available as of MySQL 5.6.6) can be used to test passwords and improve security. This plugin implements two capabilities:

For example, the cleartext password in the following statement is checked. Under the default password policy, which requires passwords to be at least 8 characters long, the password is weak and the statement produces an error:

mysql> SET PASSWORD = PASSWORD('abc');
ERROR 1819 (HY000): Your password does not satisfy the current policy
requirements

Passwords specified as already hashed values are not checked because the original password value is not available:

mysql> SET PASSWORD = '*0D3CED9BEC10A777AEC23CCC353A8C08A633045E';
Query OK, 0 rows affected (0.01 sec)

The parameters that control password checking are available as the values of the system variables having names of the form validate_password_xxx. These variables can be modified to configure password checking; see Section 2.2.6.2, “Password Validation Plugin Options and Variables”.

The three levels of password checking are LOW, MEDIUM, and STRONG. The default is MEDIUM; to change this, modify the value of validate_password_policy. The policies implement increasingly strict password tests. The following descriptions refer to default parameter values; these can be modified by changing the appropriate system variables.

If the validate_password plugin is not installed, the validate_password_xxx system variables are not available, passwords in statements are not checked, and VALIDATE_PASSWORD_STRENGTH() always returns 0. For example, accounts can be assigned passwords shorter than 8 characters.