1.RAWTOHEX函数
rawtohex作用是将一个raw类型的值转换为hexadecimal.

举例:
select">HUNTER@finnet>select rawtohex('a') hex from dual;

HE
--
61

2.UTL_RAW.CAST_TO_RAW 的用法
主要作用是将一个字符类型的值转换为raw类型.

举例:
raw_input RAW(128) := UTL_RAW.CAST_TO_RAW(input_string);

3.sys.dbms_obfuscation_toolkit.MD5用法

语法如下

DBMS_OBFUSCATION_TOOLKIT.MD5(
input IN RAW,
checksum OUT raw_checksum);

DBMS_OBFUSCATION_TOOLKIT.MD5(
input_string IN VARCHAR2,
checksum_string OUT varchar2_checksum);

DBMS_OBFUSCATION_TOOLKIT.MD5(
input IN RAW)
RETURN raw_checksum;

DBMS_OBFUSCATION_TOOLKIT.MD5(
input_string IN VARCHAR2)
RETURN varchar2_checksum;

举例:
sys.dbms_obfuscation_toolkit.MD5(input => raw_input,checksum => decrypted_raw);

来个综合例子

CREATE OR REPLACE function fn_md5(input_string VARCHAR2) return varchar2
IS
raw_input RAW(128) := UTL_RAW.CAST_TO_RAW(input_string);
decrypted_raw RAW(2048);
error_in_input_buffer_length EXCEPTION;
BEGIN
sys.dbms_obfuscation_toolkit.MD5(input => raw_input,checksum => decrypted_raw);
return rawtohex(decrypted_raw);
END;

update t_user set password = fn_md5(password) where password is not null ;

此funcation可以完成初始化原来没有加md5加密的数据.

程序中使用如下

L_Password:=UPPER(PPassword);
p_rawinput := UTL_RAW.CAST_TO_RAW(L_Password);
sys.dbms_obfuscation_toolkit.MD5(input => p_rawinput,checksum => p_decrypted_raw);
L_Password := rawtohex(p_decrypted_raw

from: http://space.itpub.net/7364032