[#MDEV-25343] Error log message not helpful when encryption key is too long

Relevant Configuration in mariadb.cnf:

[mysqld]

plugin_load_add = file_key_management

file_key_management_filename = /etc/mysql/keys/enc_key.enc

file_key_management_filekey = FILE:/etc/mysql/keys/enc_passwd.key

file_key_management_encryption_algorithm = AES_CBC

MariaDB [(none)]> show plugins soname 'file_key_management.so';

+---------------------+---------------+------------+------------------------+---------+

| Name                | Status        | Type       | Library                | License |

+---------------------+---------------+------------+------------------------+---------+

| file_key_management | NOT INSTALLED | ENCRYPTION | file_key_management.so | GPL     |

+---------------------+---------------+------------+------------------------+---------+

Error log:

Apr  6 03:29:43 localhost mariadbd[27605]: 2021-04-06  3:29:43 0 [ERROR] mariadbd: Cannot decrypt /etc/mysql/keys/enc_key.enc. Wrong key?

Apr  6 03:29:43 localhost mariadbd[27605]: 2021-04-06  3:29:43 0 [ERROR] Plugin 'file_key_management' init function returned error.

Apr  6 03:29:43 localhost mariadbd[27605]: 2021-04-06  3:29:43 0 [ERROR] Plugin 'file_key_management' registration as a ENCRYPTION failed.

After hours of trying different things, it turned out that the key was too long (I'd inadvertently used 512 characters). Recreated the file_key_management_filename and file_key_management_filekey using a 256 character key and it all worked fine.

I suggest checking the length (if not already happening) and then issuing a more helpful error like "Cannot decrypt <file_key_management_filename>. <file_key_management_filekey> has incorrect length"

This would have helped me realise where the error was (ie between chair and keyboard) and would have taken less than a minute to address.

[MDEV-25343] Error log message not helpful when encryption key is too long Created: 2021-04-06 Updated: 2022-10-21 Resolved: 2022-10-21
Status:	Closed
Project:	MariaDB Server
Component/s:	Encryption
Affects Version/s:	10.2, 10.3, 10.4, 10.5
Fix Version/s:	10.3.37, 10.4.27, 10.5.18, 10.6.11, 10.7.7, 10.8.6, 10.9.4, 10.10.2, 10.11.1

[MDEV-25343] Error log message not helpful when encryption key is too long Created: 2021-04-06 Updated: 2022-10-21 Resolved: 2022-10-21