bitcoin/bitcoin — pull request #950 by sipa (2012-03-19 01:05:50+00:00)
Title: Use unpadded encryption for wallet keys (fixes #933)

Wallet keys are 32 bytes, exactly two AES blocks. Using padded encryption makes attacking somewhat easier, as the attacker can check whether the padding is correct after decrypting using an attempted passphrase, rather than needing to do an EC multiplication to check whether the private and public keys match.