oracle的function如何转成Sql server2000的function

下边oracle的function如何转成Sql server2000的function,高手们都来帮帮我哦
CREATE OR REPLACE FUNCTION MD5(
passwd   IN   VARCHAR2)
RETURN   VARCHAR2
IS
  retval   varchar2(32);
BEGIN
  retval   :=   utl_raw.cast_to_raw(DBMS_OBFUSCATION_TOOLKIT.MD5(INPUT_STRING   =>   passwd))   ;
  RETURN   retval;
END;