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Security in MySQL  /  ...  /  Password Validation Options and Variables

6.3.2 Password Validation Options and Variables

This section describes the system and status variables that validate_password provides to enable its operation to be configured and monitored.

Password Validation Component System Variables

If the validate_password component is enabled, it exposes several system variables that enable configuration of password checking: 

mysql> SHOW VARIABLES LIKE 'validate_password.%';
+-------------------------------------------------+--------+
| Variable_name                                   | Value  |
+-------------------------------------------------+--------+
| validate_password.changed_characters_percentage | 0      |
| validate_password.check_user_name               | ON     |
| validate_password.dictionary_file               |        |
| validate_password.length                        | 8      |
| validate_password.mixed_case_count              | 1      |
| validate_password.number_count                  | 1      |
| validate_password.policy                        | MEDIUM |
| validate_password.special_char_count            | 1      |
+-------------------------------------------------+--------+

To change how passwords are checked, you can set these system variables at server startup or at runtime. The following list describes the meaning of each variable.

  • validate_password.changed_characters_percentage

    Command-Line Format --validate-password.changed-characters-percentage[=value]
    Introduced 8.0.34
    System Variable validate_password.changed_characters_percentage
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 0
    Minimum Value 0
    Maximum Value 100

    Indicates the minimum number of characters, as a percentage of all characters, in a password that a user must change before validate_password accepts a new password for the user's own account. This applies only when changing an existing password, and has no effect when setting a user account's initial password.

    This variable is not available unless validate_password is installed.

    By default, validate_password.changed_characters_percentage permits all of the characters from the current password to be reused in the new password. The range of valid percentages is 0 to 100. If set to 100 percent, all of the characters from the current password are rejected, regardless of the casing. Characters 'abc' and 'ABC' are considered to be the same characters. If validate_password rejects the new password, it reports an error indicating the minimum number of characters that must differ.

    If the ALTER USER statement does not provide the existing password in a REPLACE clause, this variable is not enforced. Whether the REPLACE clause is required is subject to the password verification policy as it applies to a given account. For an overview of the policy, see Password Verification-Required Policy.

  • validate_password.check_user_name

    Command-Line Format --validate-password.check-user-name[={OFF|ON}]
    System Variable validate_password.check_user_name
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Boolean
    Default Value ON

    Whether validate_password compares passwords to the user name part of the effective user account for the current session and rejects them if they match. This variable is unavailable unless validate_password is installed.

    By default, validate_password.check_user_name is enabled. This variable controls user name matching independent of the value of validate_password.policy.

    When validate_password.check_user_name is enabled, it has these effects:

    • Checking occurs in all contexts for which validate_password is invoked, which includes use of statements such as ALTER USER or SET PASSWORD to change the current user's password, and invocation of functions such as VALIDATE_PASSWORD_STRENGTH().

    • The user names used for comparison are taken from the values of the USER() and CURRENT_USER() functions for the current session. An implication is that a user who has sufficient privileges to set another user's password can set the password to that user's name, and cannot set that user' password to the name of the user executing the statement. For example, 'root'@'localhost' can set the password for 'jeffrey'@'localhost' to 'jeffrey', but cannot set the password to 'root.

    • Only the user name part of the USER() and CURRENT_USER() function values is used, not the host name part. If a user name is empty, no comparison occurs.

    • If a password is the same as the user name or its reverse, a match occurs and the password is rejected.

    • User-name matching is case-sensitive. The password and user name values are compared as binary strings on a byte-by-byte basis.

    • If a password matches the user name, VALIDATE_PASSWORD_STRENGTH() returns 0 regardless of how other validate_password system variables are set.

  • validate_password.dictionary_file

    Command-Line Format --validate-password.dictionary-file=file_name
    System Variable validate_password.dictionary_file
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type File name

    The path name of the dictionary file that validate_password uses for checking passwords. This variable is unavailable unless validate_password is installed.

    By default, this variable has an empty value and dictionary checks are not performed. For dictionary checks to occur, the variable value must be nonempty. If the file is named as a relative path, it is interpreted relative to the server data directory. File contents should be lowercase, one word per line. Contents are treated as having a character set of utf8mb3. The maximum permitted file size is 1MB.

    For the dictionary file to be used during password checking, the password policy must be set to 2 (STRONG); see the description of the validate_password.policy system variable. Assuming that is true, each substring of the password of length 4 up to 100 is compared to the words in the dictionary file. Any match causes the password to be rejected. Comparisons are not case-sensitive.

    For VALIDATE_PASSWORD_STRENGTH(), the password is checked against all policies, including STRONG, so the strength assessment includes the dictionary check regardless of the validate_password.policy value.

    validate_password.dictionary_file can be set at runtime and assigning a value causes the named file to be read without a server restart.

  • validate_password.length

    Command-Line Format --validate-password.length=#
    System Variable validate_password.length
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 8
    Minimum Value 0

    The minimum number of characters that validate_password requires passwords to have. This variable is unavailable unless validate_password is installed.

    The validate_password.length minimum value is a function of several other related system variables. The value cannot be set less than the value of this expression: 

    validate_password.number_count
+ validate_password.special_char_count
+ (2 * validate_password.mixed_case_count)

    If validate_password adjusts the value of validate_password.length due to the preceding constraint, it writes a message to the error log.

  • validate_password.mixed_case_count

    Command-Line Format --validate-password.mixed-case-count=#
    System Variable validate_password.mixed_case_count
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 1
    Minimum Value 0

    The minimum number of lowercase and uppercase characters that validate_password requires passwords to have if the password policy is MEDIUM or stronger. This variable is unavailable unless validate_password is installed.

    For a given validate_password.mixed_case_count value, the password must have that many lowercase characters, and that many uppercase characters.

  • validate_password.number_count

    Command-Line Format --validate-password.number-count=#
    System Variable validate_password.number_count
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 1
    Minimum Value 0

    The minimum number of numeric (digit) characters that validate_password requires passwords to have if the password policy is MEDIUM or stronger. This variable is unavailable unless validate_password is installed.

  • validate_password.policy

    Command-Line Format --validate-password.policy=value
    System Variable validate_password.policy
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Enumeration
    Default Value 1
    Valid Values

    0

    1

    2

    The password policy enforced by validate_password. This variable is unavailable unless validate_password is installed.

    validate_password.policy affects how validate_password uses its other policy-setting system variables, except for checking passwords against user names, which is controlled independently by validate_password.check_user_name.

    The validate_password.policy value can be specified using numeric values 0, 1, 2, or the corresponding symbolic values LOW, MEDIUM, STRONG. The following table describes the tests performed for each policy. For the length test, the required length is the value of the validate_password.length system variable. Similarly, the required values for the other tests are given by other validate_password.xxx variables.

    Policy Tests Performed
    0 or LOW Length
    1 or MEDIUM Length; numeric, lowercase/uppercase, and special characters
    2 or STRONG Length; numeric, lowercase/uppercase, and special characters; dictionary file

  • validate_password.special_char_count

    Command-Line Format --validate-password.special-char-count=#
    System Variable validate_password.special_char_count
    Scope Global
    Dynamic Yes
    SET_VAR Hint Applies No
    Type Integer
    Default Value 1
    Minimum Value 0

    The minimum number of nonalphanumeric characters that validate_password requires passwords to have if the password policy is MEDIUM or stronger. This variable is unavailable unless validate_password is installed.

Password Validation Component Status Variables

If the validate_password component is enabled, it exposes status variables that provide operational information: 

mysql> SHOW STATUS LIKE 'validate_password.%';
+-----------------------------------------------+---------------------+
| Variable_name                                 | Value               |
+-----------------------------------------------+---------------------+
| validate_password.dictionary_file_last_parsed | 2019-10-03 08:33:49 |
| validate_password.dictionary_file_words_count | 1902                |
+-----------------------------------------------+---------------------+

The following list describes the meaning of each status variable.

Password Validation Plugin Options

Note

In MySQL 8.0, the validate_password plugin was reimplemented as the validate_password component. The validate_password plugin is deprecated; expect it to be removed in a future version of MySQL. Consequently, its options are also deprecated, and you should expect them to be removed as well. MySQL installations that use the plugin should make the transition to using the component instead. See Section 6.3.3, “Transitioning to the Password Validation Component”.

To control activation of the validate_password plugin, use this option:

Password Validation Plugin System Variables

Note

In MySQL 8.0, the validate_password plugin was reimplemented as the validate_password component. The validate_password plugin is deprecated; expect it to be removed in a future version of MySQL. Consequently, its system variables are also deprecated and you should expect them to be removed as well. Use the corresponding system variables of the validate_password component instead; see Password Validation Component System Variables. MySQL installations that use the plugin should make the transition to using the component instead. See Section 6.3.3, “Transitioning to the Password Validation Component”.

Password Validation Plugin Status Variables

Note

In MySQL 8.0, the validate_password plugin was reimplemented as the validate_password component. The validate_password plugin is deprecated; expect it to be removed in a future version of MySQL. Consequently, its status variables are also deprecated; expect it to be removed. Use the corresponding status variables of the validate_password component; see Password Validation Component Status Variables. MySQL installations that use the plugin should make the transition to using the component instead. See Section 6.3.3, “Transitioning to the Password Validation Component”.


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Related Documentation
MySQL 8.0 Reference Manual
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