Encriptar datos en la base de datos

Antes que nada disculpa la demora, no te imaginas lo cargado de estos meses.
Respondiendo a tu pregunta (si es que todavia puedo serte de utilidad),
DBMS_OBFUSCATION_TOOLKIT provee de algoritmos de encryptacion basados en estandares.
Estas rutinas estan perfectamente documentadas en:
http://download-west.oracle.com/docs/cd/B14117_01/appdev.101/b10802/d_obtool.htm#1002213
Aqui un ejemplo de como utilizarlo:
-- encrypt.sql
-- demonstrates the use of the dbms_obfuscation_toolkit by
-- Prompting a user for a password and encrypting and decrypting
-- The data
set serveroutput on;
CLEAR BUFFER
PROMPT Please enter a password - Must be 8 characters !
PROMPT
ACCEPT PASSWD
DECLARE
input_string VARCHAR2(16) := '&PASSWD';
raw_input RAW(128) := UTL_RAW.CAST_TO_RAW(input_string);
key_string VARCHAR2(16) := 'keepthesecretnum';
raw_key RAW(128) := UTL_RAW.CAST_TO_RAW(key_string);
encrypted_raw RAW(2048);
encrypted_string VARCHAR2(2048);
decrypted_raw RAW(2048);
decrypted_string VARCHAR2(2048);
error_in_input_buffer_length EXCEPTION;
PRAGMA EXCEPTION_INIT(error_in_input_buffer_length, -28232);
INPUT_BUFFER_LENGTH_ERR_MSG VARCHAR2(100) :=
'*** DES INPUT BUFFER NOT A MULTIPLE OF 8 BYTES - IGNORING EXCEPTION ***';
double_encrypt_not_permitted EXCEPTION;
PRAGMA EXCEPTION_INIT(double_encrypt_not_permitted, -28233);
DOUBLE_ENCRYPTION_ERR_MSG VARCHAR2(100) :=
'*** CANNOT DOUBLE ENCRYPT DATA - IGNORING EXCEPTION ***';
-- 1. Begin testing raw data encryption and decryption
BEGIN
dbms_output.put_line('> ========= BEGIN TEST RAW DATA =========');
dbms_output.put_line('> Raw input : ' ||
UTL_RAW.CAST_TO_VARCHAR2(raw_input));
BEGIN
dbms_obfuscation_toolkit.DESEncrypt(input => raw_input,
key => raw_key, encrypted_data => encrypted_raw );
dbms_output.put_line('> encrypted hex value : ' ||
rawtohex(encrypted_raw));
dbms_obfuscation_toolkit.DESDecrypt(input => encrypted_raw,
key => raw_key, decrypted_data => decrypted_raw);
dbms_output.put_line('> Decrypted raw output : ' ||
UTL_RAW.CAST_TO_VARCHAR2(decrypted_raw));
dbms_output.put_line('> ');
if UTL_RAW.CAST_TO_VARCHAR2(raw_input) =
UTL_RAW.CAST_TO_VARCHAR2(decrypted_raw) THEN
dbms_output.put_line('> Raw DES Encyption and Decryption successful');
END if;
EXCEPTION
WHEN error_in_input_buffer_length THEN
dbms_output.put_line('> ' || INPUT_BUFFER_LENGTH_ERR_MSG);
END;
dbms_output.put_line('> ');
END;
/
La salida de este ejemplo debe ser:
SQL> start encrypt
Please enter a password - Must be 8 characters !
Wildwind
old 2: input_string VARCHAR2(16) := '&PASSWD';
new 2: input_string VARCHAR2(16) := 'wildwind';
> ========= BEGIN TEST RAW DATA =========
> Raw input : wildwind
> encrypted hex value : 28EAA8E9E2CEA710
> Decrypted raw output : wildwind
>
> Raw DES Encyption and Decryption successful
>
PL/SQL procedure successfully completed.

Perdona, creo que no me he explicado con claridad. Mi pregunta era que de alguna forma tengo que gestionar la clave, es decir, en el ejemplo que me has mandado utilizas como clave de encriptación 'keepthesecretnum', ¿donde guardo dicha clave? Muchas gracias