contrib/pgcrypto in PostgreSQL before 9.0.20, 9.1.x before 9.1.16, 9.2.x before 9.2.11, 9.3.x before 9.3.7, and 9.4.x before 9.4.2 uses different error responses when an incorrect key is used, which makes it easier for attackers to obtain the key via a brute force attack.