Oracle defines examples of DES encryption, decryption and MD5 encryption functions

create or replace function
encrypt_des(p_text varchar2, p_key varchar2) return varchar2 is
v_text varchar2(4000);
v_enc varchar2(4000);
raw_input RAW(128) ;
key_input RAW(128) ;
decrypted_raw RAW(2048);
begin
v_text := rpad( p_text, (trunc(length(p_text)/8)+1)*8, chr(0));
raw_input := UTL_RAW.CAST_TO_RAW(v_text);
key_input := UTL_RAW.CAST_TO_RAW(p_key);
dbms_obfuscation_toolkit.DESEncrypt(input => raw_input,key => key_input,encrypted_data =>decrypted_raw);
v_enc := rawtohex(decrypted_raw);
dbms_output.put_line(v_enc);
return v_enc;
end;

create or replace function decrypt_des(p_text varchar2,p_key varchar2) return varchar2 is
v_text varchar2(2000);
begin
dbms_obfuscation_toolkit.DESDECRYPT(input_string => UTL_RAW.CAST_TO_varchar2(p_text),key_string =>p_key, decrypted_string=> v_text);
v_text := rtrim(v_text,chr(0));
dbms_output.put_line(v_text);
return v_text;
end;

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;