译文 | MySQL 8.0 密码管理策略（一）

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原文链接：https://www.percona.com/blog/...

MySQL 8.0 在密码管理方面有很多改善，本文将介绍以下两个特性。

• 密码重用策略
• 生成随机密码

| 1 密码重用策略

该策略简单说，就是设置新密码时，可以限制禁止使用曾经用过的密码。有以下两种策略：

• 历史密码 password_history
• 间隔时间 password_reuse_interval

1.1 历史密码

MySQL 官方手册描述：

If an account is restricted on the basis of number of password changes, a new password cannot be chosen from a specified number of the most recent passwords.

在实验环境中，创建用户并添加条件

password history 2

mysql> create user 'herc'@'localhost' identified by 'Percona@321' password history 2;
Query OK, 0 rows affected (0.02 sec)

mysql> select user, host, password_reuse_history from mysql.user where user='herc'\G
*************************** 1. row ***************************
                  user: herc
                  host: localhost
password_reuse_history: 2
1 row in set (0.00 sec)

MySQL 将在

mysql.password_history

mysql> select * from mysql.password_history;
+-----------+------+----------------------------+------------------------------------------------------------------------+
| Host      | User | Password_timestamp         | Password                                                               |
+-----------+------+----------------------------+------------------------------------------------------------------------+
| localhost | herc | 2021-09-20 15:44:42.295778 | $A$005$=R:q'M(Kh#D];c~SdCLyluq2UVHFobjWOFTwn2JYVFDyI042sl56B7DCPSK5 |
+-----------+------+----------------------------+------------------------------------------------------------------------+
1 row in set (0.00 sec)

接下来我们尝试更改用户

herc@localhost

mysql> alter user 'herc'@'localhost' identified by 'MySQL@321';
Query OK, 0 rows affected (0.02 sec)

mysql> select * from mysql.password_history\G
*************************** 1. row ***************************
              Host: localhost
              User: herc
Password_timestamp: 2021-09-20 15:49:15.459018
CGeRQT31UUwtw194KOKGdNbgj3558VUB.dxcoS8r4IKpG8
*************************** 2. row ***************************
              Host: localhost
              User: herc
Password_timestamp: 2021-09-20 15:44:42.295778
          Password: $A$005$=R:q'M(Kh#D];c~SdCLyluq2UVHFobjWOFTwn2JYVFDyI042sl56B7DCPSK5
2 rows in set (0.00 sec)

更改成功后，查看

mysql.password_history

再次更改该用户密码，且密码为创建用户时设置的密码值（Percona@321）。

mysql> alter user 'herc'@'localhost' identified by 'Percona@321';
ERROR 3638 (HY000): Cannot use these credentials for 'herc@localhost' because they contradict the password history policy

修改失败! 因为根据我们设置的限制策略，不能重用在

mysql.password_policy

mysql.password_policy

再设置一个新密码后（第一个密码已经不是最近的两个密码了），再尝试用第一个密码值（Percona@321）进行修改，修改成功！

mysql> alter user 'herc'@'localhost' identified by 'Herc@321';
Query OK, 0 rows affected (0.01 sec)

mysql> alter user 'herc'@'localhost' identified by 'Percona@321';
Query OK, 0 rows affected (0.02 sec)

也可以在启动时在全局配置

password_history

#vi my.cnf
[mysqld]
password_history=6

#set global
mysql> set global password_history=5;
Query OK, 0 rows affected (0.00 sec)

1.2 间隔时间

MySQL 官方手册描述：

If an account is restricted based on time elapsed, a new password cannot be chosen from passwords in the history that are newer than a specified number of days.

测试前，创建了用户

sri@localhost

mysql> create user 'sri'@'localhost' identified by 'Percona@321' password reuse interval 5 day;
Query OK, 0 rows affected (0.01 sec)

mysql> select user, host, password_reuse_time from mysql.user where user='sri'\G
*************************** 1. row ***************************
               user: sri
               host: localhost
password_reuse_time: 5
1 row in set (0.00 sec)

这意味着每个密码生效后，在五天内都不能再被重复设置。

mysql> select * from mysql.password_history where user='sri'\G
*************************** 1. row ***************************
              Host: localhost
              User: sri
Password_timestamp: 2021-09-20 16:09:27.918585
          Password: $A$005$+B   e3!C9&8m
                                         eFRG~IqRWX4b6PtzLA8I4VsdYvWU3qRs/nip/QRhXXR5phT6
1 row in set (0.00 sec)

执行 ALTER 来更改密码。

mysql> alter user 'sri'@'localhost' identified by 'Herc@321';
Query OK, 0 rows affected (0.02 sec)

mysql> select * from mysql.password_history where user='sri'\G
*************************** 1. row ***************************
              Host: localhost
              User: sri
Password_timestamp: 2021-09-20 16:17:51.840483
          Password: $A$005$~k7qp8.OP=^#e79qwtiYd7/cmCFLvHM7MHFbvfX2WlhXqzjmrN03gGZ4
*************************** 2. row ***************************
              Host: localhost
              User: sri
Password_timestamp: 2021-09-20 16:09:27.918585
          Password: $A$005$+B   e3!C9&8m
                                         eFRG~IqRWX4b6PtzLA8I4VsdYvWU3qRs/nip/QRhXXR5phT6
2 rows in set (0.00 sec)

现在尝试再次设置为第一个密码。

mysql> alter user 'sri'@'localhost' identified by 'Percona@321';
ERROR 3638 (HY000): Cannot use these credentials for 'sri@localhost' because they contradict the password history policy

设置失败！

也可以在启动时在全局配置

password_reuse_interval

#vi my.cnf
[mysqld]
password_reuse_interval=365

#set global
mysql> set global password_reuse_interval=365;
Query OK, 0 rows affected (0.00 sec)

| 2 随机密码

从 MySQL 8.0.18 开始，MySQL 能够为用户帐户创建随机密码。这意味着可以不必分配指定密码。它支持以下语句：

• 创建用户
• 更改用户
• 设置密码

我们需要使用

RANDOM PASSWORD

mysql> create user 'sakthi'@'localhost' identified by random password;
+--------+-----------+----------------------+
| user   | host      | generated password   |
+--------+-----------+----------------------+
| sakthi | localhost | .vZYy+ alter user 'sri'@'localhost' identified by random password;
+------+-----------+----------------------+
| user | host      | generated password   |
+------+-----------+----------------------+
| sri  | localhost | 5wb>2[]q*jbDsFvlN-i_ |
+------+-----------+----------------------+
1 row in set (0.02 sec)

密码哈希值将存储在

mysql.user

mysql> select user, authentication_string from mysql.user where user in ('sakthi','sri')\G
*************************** 1. row ***************************
                 user: sakthi
authentication_string: $A$005$L`PYcedj%3tz*J>ioBP1.Rsrj7H8wtelqijvV0CFnXVnWLNIc/RZL0C06l4oA
*************************** 2. row ***************************
                 user: sri
authentication_string: $A$005$/k?aO&ap.#b=
                                          ^zt[E|x9q3w9uHn1oEumXUgnqNMH8xWo4xd/s26hTPKs1AbC2
2 rows in set (0.00 sec)

默认情况下，密码长度为 20 个字符。我们可以使用变量

generated_random_password_length

mysql> select @@generated_random_password_length;
+------------------------------------+
| @@generated_random_password_length |
+------------------------------------+
|                                 20 |
+------------------------------------+
1 row in set (0.00 sec)

如果

validate_password

还有一些特性，将在下一篇文章中介绍。

参考

MySQL 手册：

• https://dev.mysql.com/doc/mys...
• https://dev.mysql.com/doc/ref...

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