6.4.4.3 Using the keyring_encrypted_file Keyring Plugin

The keyring_encrypted_file plugin is a keyring plugin that stores keyring data in an encrypted file local to the server host. This plugin is available as of MySQL 5.7.21.

To install the keyring_encrypted_file plugin, use the general keyring installation instructions found in Section 6.4.4.1, “Keyring Plugin Installation”, together with the configuration information specific to keyring_encrypted_file found here.

To be usable during the server startup process, keyring_encrypted_file must be loaded using the --early-plugin-load option. To specify the password for encrypting the keyring data file, set the keyring_encrypted_file_password system variable. (The password is mandatory; if not specified at server startup, keyring_encrypted_file initialization fails.) The keyring_encrypted_file_data system variable optionally configures the location of the file used by the keyring_encrypted_file plugin for data storage. The default value is platform specific. To configure the file location explicitly, set the variable value at startup. For example, use these lines in the server my.cnf file (adjust the .so suffix and file location for your platform as necessary and substitute your chosen password):

[mysqld]
early-plugin-load=keyring_encrypted_file.so
keyring_encrypted_file_data=/usr/local/mysql/mysql-keyring/keyring-encrypted
keyring_encrypted_file_password=password

Because the my.cnf file stores a password when written as shown, it should have a restrictive mode and be accessible only to the account used to run the MySQL server.

Keyring operations are transactional: The keyring_encrypted_file plugin uses a backup file during write operations to ensure that it can roll back to the original file if an operation fails. The backup file has the same name as the value of the keyring_encrypted_file_data system variable with a suffix of .backup.

For additional information about the system variables used to configure the keyring_encrypted_file plugin, see Section 6.4.4.11, “Keyring System Variables”.

To ensure that keys are flushed only when the correct keyring storage file exists, keyring_encrypted_file stores a SHA-256 checksum of the keyring in the file. Before updating the file, the plugin verifies that it contains the expected checksum. In addition, keyring_encrypted_file encrypts file contents using AES before writing the file, and decrypts file contents after reading the file.

The keyring_encrypted_file plugin supports the functions that comprise the standard keyring service interface. Keyring operations performed by those functions are accessible at two levels:

Example (using UDFs):

The key types permitted by keyring_encrypted_file are described in Section 6.4.4.7, “Supported Keyring Key Types”.