MySQL 8.0. Security; support for two passwords.

Preamble

Reflecting on security in MySQL installation, you can consider a wide range of possible procedures/recommendations and their impact on the security of your MySQL server and related applications.

MySQL provides many tools/functions/plugins or components to protect your data, including some additional features such as Transparent Data Encryption (TDE), auditing, data masking and de-identification, firewall, login failure tracking and temporary account locking, connection control plugins, password verification component, etc…

TL; DR

Dual password capability allows you to make changes to your credentials without any problems.

MySQL implements a double password with syntax that saves and discards secondary passwords:

• The RETAIN CURRENT PASSWORD offer for ALTER USER and SET PASSWORD operators saves the current account password as a secondary password when assigning a new master password.
• The DISCARD OLD PASSWORD for ALTER USER casts an additional account password, leaving only the master password. The goal is to avoid downtime when changing passwords in replicated environments.

Customers can use the old password as long as the new password is set in the server group and only delete the old password when the new password is set in the entire group.

Workflow:

On each server that is not a replication slave, set a new password, for example:

ALTER USER 'myApp'@'host' IDENTIFIED BY 'NEW_password' RETAIN CURRENT PASSWORD;

Wait until the change of password spreads throughout the system to all slave servers.

Change each application that uses myApp account to connect to servers using the password “NEW_password” rather than “OLD_password”.

On each server that is not a replication slave, reset the secondary password, for example:

ALTER USER 'myApp'@'host' DISCARD OLD PASSWORD;

Let’s take a brief look at using MySQL 8.0

MySQL SQL> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 8.0.19 |
+-----------+

Create user account myApp@localhost with password pwd1 :

MySQL root SQL>
CREATE USER myApp@localhost IDENTIFIED BY 'pwd1';

We can now contact you with a username and password:

$ mysql -u myApp -ppwd1 -e "SELECT USER()".
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------+
| USER() |
+-----------------+
| myApp@localhost |
+-----------------+

Note: As indicated in the output, entering a password into the command line interface is bad practice.

Now the database administrator (superuser) uses the ALTER USER instruction with the RETAIN CURRENT PASSWORD sentence to modify the credentials using the double password mechanism by adding pwd2 as the main password.

Thus, pwd1 is now the secondary password:

MySQL root SQL>
ALTER USER myApp@localhost IDENTIFIED BY 'pwd2' RETAIN CURRENT PASSWORD;

We can use our username and new password ( pwd2 ) to connect:

$ mysql -u myApp -ppwd2 -e "SELECT USER()".
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------+
| USER() |
+-----------------+
| myApp@localhost |
+-----------------+

But the old password ( pwd1 ) is still valid:

$ mysql -u myApp -ppwd1 -e "SELECT USER()"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------+
| USER() |
+-----------------+
| myApp@localhost |
+-----------------+

Now it is time to reset the additional password ( pwd1 ):

MySQL root SQL>
ALTER USER myApp@localhost DISCARD OLD PASSWORD;

$ mysql -u myApp -ppwd2 -e "SELECT USER()"
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------------+
| USER() |
+-----------------+
| myApp@localhost |
+-----------------+

$ mysql -u myApp -ppwd1 -e "SELECT USER()"
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user 'myApp'@'localhost' (using password: YES)

As you can see, only the new password ( pwd2 ) is valid.

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