MySQL Keyring supports keys of different types (encryption algorithms) and lengths:
The available key types depend on which keyring plugin is installed.
The permitted key lengths are subject to multiple factors:
General keyring loadable-function interface limits (for keys managed using one of the keyring functions described in Section 6.4.4.14, “General-Purpose Keyring Key-Management Functions”), or limits from back end implementations. These length limits can vary by key operation type.
In addition to the general limits, individual keyring plugins may impose restrictions on key lengths per key type.
Table 6.26, “General Keyring Key Length Limits” shows the general key-length limits. (The lower limits for keyring_aws are imposed by the AWS KMS interface, not the keyring functions.) For keyring plugins, Table 6.27, “Keyring Plugin Key Types and Lengths” shows the key types each keyring plugin permits, as well as any plugin-specific key-length restrictions. For keyring components, the general key-length limits apply and there are no key-type restrictions.
Table 6.26 General Keyring Key Length Limits
| Key Operation | Maximum Key Length |
|---|---|
| Generate key | 16,384 bytes (2,048 prior to MySQL 8.0.18); 1,024 for |
| Store key | 16,384 bytes (2,048 prior to MySQL 8.0.18); 4,096 for |
| Fetch key | 16,384 bytes (2,048 prior to MySQL 8.0.18); 4,096 for |
Table 6.27 Keyring Plugin Key Types and Lengths
| Plugin Name | Permitted Key Type | Plugin-Specific Length Restrictions |
|---|---|---|
keyring_aws |
| 16, 24, or 32 bytes None |
keyring_encrypted_file |
| None None None None |
keyring_file |
| None None None None |
keyring_hashicorp |
| None None None None |
keyring_oci |
| 16, 24, or 32 bytes |
keyring_okv |
| 16, 24, or 32 bytes None |
The SECRET key type, available as of MySQL 8.0.19, is intended for general-purpose storage of sensitive data using the MySQL keyring, and is supported by all keyring components and most keyring plugins. The keyring encrypts and decrypts SECRET data as a byte stream upon storage and retrieval.
Example keyring operations involving the SECRET key type:
SELECT keyring_key_generate('MySecret1', 'SECRET', 20);
SELECT keyring_key_remove('MySecret1');
SELECT keyring_key_store('MySecret2', 'SECRET', 'MySecretData');
SELECT keyring_key_fetch('MySecret2');
SELECT keyring_key_length_fetch('MySecret2');
SELECT keyring_key_type_fetch('MySecret2');
SELECT keyring_key_remove('MySecret2');