Audit Log Filter compression and encryption¶
Compression¶
You can enable compression for any format by setting the audit_log_filter_compression system variable when the server starts.
The audit_log_filter_compression variable can be either of the following:
- NONE (no compression) - the default value
- GZIP - uses the GNU Zip compression
If compression and encryption are enabled, the plugin applies compression before encryption. If you must manually recover a file with both settings, first decrypt the file and then uncompress the file.
Encryption¶
You can encrypt any audit log filter file in any format. The audit log filter plugin generates the initial password, but you can use user-defined passwords after that. The plugin stores the passwords in the keyring, so that feature must be enabled.
Set the audit_log_filter_encryption system variable with the server starts. The allowed values are the following:
- NONE - no encryption, the default value
- AES - AES-256-CBC (Cipher Block Chaining) encryption
The AES uses the 256-bit key size.
The following audit log filter functions are used with encryption:
| Function name | Description |
|---|---|
| audit_log_encryption_password_set() | Stores the password in the keyring. If encryption is enabled, the function also rotates the log file by renaming the current log file and creating a log file encrypted with the password. |
| audit_log_encryption_password_get() | Invoking this function without an argument returns the current encryption password. An argument that specifies the keyring ID of an archived password or current password returns that password by ID. |
The audit_log_filter_password_history_keep_days variable is used with encryption. If the variable is not zero (0) , invoking audit_log_encryption_password_set() causes the expiration of archived audit log passwords.
When the plugin starts with encryption enabled, the plugin checks if the keyring has an audit log filter encryption password. If no password is found, the plugin generates a random password and stores this password in the keyring. Use audit_log_encryption_password_get() to review this password.
If compression and encryption are enabled, the plugin applies compression before encryption. If you must manually recover a file with both settings, first decrypt the file and then uncompress the file.
Manually uncompressing and decrypting audit log filter files¶
To decrypt an encrypted log file, use the openssl command. For example:
openssl enc -d -aes-256-cbc -pass pass:password
-iter iterations -md sha256
-in audit.timestamp.log.pwd_id.enc
-out audit.timestamp.log
To execute that command, you must obtain a password and iterations. To do this, use audit_log_encryption_password_get().
This function gets the encryption password, and the iterations count and returns this data as a JSON-encoded string. For example, if the audit log file name is audit.20190415T151322.log.20190414T223342-2.enc, the password ID is {randomly-generated-alphanumeric-string}-2 and the keyring ID is audit-log-20190414T223342-2.
Get the keyring password:
mysql> SELECT audit_log_encryption_password_get('audit-log-20190414T223342-2');
The return value of this function may look like the following:
Expected output
{"password":"{randomly-generated-alphanumeric-string}","iterations":568977}
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