--加密
function encrypt_aes256 (p_blob in blob,
 p_key in varchar2) return blob
as
 l_key_raw raw(32);
 l_returnvalue blob;
begin

 /*

 Purpose: encrypt blob

 Remarks: p_key should be 32 characters (256 bits / 8 = 32 bytes)

 Who Date Description
 ------ ---------- -------------------------------------
 MBR 20.01.2011 Created

 */
 --獲得 raw類型的key
 l_key_raw := utl_raw.cast_to_raw (p_key);
 
 dbms_lob.createtemporary (l_returnvalue, false);

 dbms_crypto.encrypt (l_returnvalue, p_blob, g_encryption_type_aes, l_key_raw);

 return l_returnvalue;

end encrypt_aes256;

--解密 
function decrypt_aes256 (p_blob in blob,
 p_key in varchar2) return blob
as
 l_key_raw raw(32);
 l_returnvalue blob;
begin

 /*

 Purpose: decrypt blob

 Remarks: p_key should be 32 characters (256 bits / 8 = 32 bytes)

 Who Date Description
 ------ ---------- -------------------------------------
 MBR 20.01.2011 Created

 */

 l_key_raw := utl_raw.cast_to_raw (p_key);

 dbms_lob.createtemporary (l_returnvalue, false);

 dbms_crypto.decrypt (l_returnvalue, p_blob, g_encryption_type_aes, l_key_raw);

 return l_returnvalue;

end decrypt_aes256;