SM4_DECRYPT

Syntax

SM4_DECRYPT(str,key_str[,init_vector])

Purpose

AES_DECRYPT() returns the plaintext obtained by decrypting the ciphertext specified by str by using the key specified by key_str and the SM4 algorithm.

For more information about the init_vector parameter, see SM4_ENCRYPT.

Examples

1. In sm4-ecb mode, SM4_DECRYPT() accepts two arguments {str, key_str}. If three values are passed in, the third value is ignored. Here is an example:

   SET block_encryption_mode = 'sm4-ecb';
   
   SELECT hex(sm4_decrypt('asdasdasdasd', '12312313123'))  FROM dual;
   +-------------------------------------------------+
   | hex(sm4_decrypt('asdasdasdasd', '12312313123')) |
   +-------------------------------------------------+
   | NULL                                            |
   +-------------------------------------------------+
   1 row in set
   

2. In sm4-cbc, sm4-cfb, and sm4-ofb modes, SM4_DECRYPT() accepts only three arguments. Here is an example:

   SET block_encryption_mode= 'sm4-cbc';
   
   SELECT hex(sm4_decrypt('asdasdasdasd', '12312313123', 'asdasdkljasdkljalskdjaklsdjaklsjdaklsdjlaksdj'))  FROM dual;
   +--------------------------------------------------------------------------------------------------+
   | hex(sm4_decrypt('asdasdasdasd', '12312313123', 'asdasdkljasdkljalskdjaklsdjaklsjdaklsdjlaksdj')) |
   +--------------------------------------------------------------------------------------------------+
   | NULL                                                                                             |
   +--------------------------------------------------------------------------------------------------+
   1 row in set