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Security in MySQL  /  ...  /  Supported Keyring Key Types and Lengths

6.4.7 Supported Keyring Key Types and Lengths

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 UDF interface limits (for keys managed using one of the keyring UDFs described in Section 6.4.8, “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 plugins may impose restrictions on key lengths per key type.

Table 6.14, “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 UDFs.) Table 6.15, “Keyring Plugin Key Types and Lengths” shows for each keyring plugin the key types it permits, as well as any plugin-specific key-length restrictions.

Table 6.14 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 keyring_aws

Store key

16,384 bytes (2,048 prior to MySQL 8.0.18); 4,096 for keyring_aws

Fetch key

16,384 bytes (2,048 prior to MySQL 8.0.18); 4,096 for keyring_aws


Table 6.15 Keyring Plugin Key Types and Lengths

Plugin Name Permitted Key Type Plugin-Specific Length Restrictions
keyring_encrypted_file

AES

DSA

RSA

SECRET

None

None

None

None

keyring_file

AES

DSA

RSA

SECRET

None

None

None

None

keyring_okv

AES

SECRET

16, 24, or 32 bytes

None

keyring_aws

AES

SECRET

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 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');