mcrypt_cfb Encrypt/decrypt data in CFB mode stringmcrypt_cfb intcipher stringkey stringdata intmode stringiv stringmcrypt_cfb stringcipher stringkey stringdata intmode stringiv The first prototype is when linked against libmcrypt 2.2.x, the second when linked against libmcrypt 2.4.x or higher. This function should not be used anymore, see mcrypt_generic and mdecrypt_generic for replacements.