DBMS_CRYPTO

synopsis:

select sys.DBMS_CRYPTO.HASH( utl_raw.cast_to_raw(v_string), v_type) from dual;

example:

select sys.DBMS_CRYPTO.HASH(UTL_I18N.STRING_TO_RAW ('tata toto titi','AL32UTF8'), 3) from dual;
select sys.DBMS_CRYPTO.HASH( utl_raw.cast_to_raw('tata toto titi'), 3) from dual;

variables:
- v_type can be 1 (MD4), 2 (MD5), 3 (SH1)
- v_string has to be converted using utl_raw.cast_to_raw or UTL_I18N.STRING_TO_RAW.

references:
http://psoug.org/reference/dbms_crypto.html 

Encrypt in AES 128: The code bellow will encrypt tha string "tata titi toto":

DECLARE
enc_val   RAW(2000);
l_key     RAW(2000);
l_key_len NUMBER := 128/8; -- convert bits to bytes
l_mod     NUMBER := dbms_crypto.ENCRYPT_AES128
+ dbms_crypto.CHAIN_CBC + dbms_crypto.PAD_ZERO;

BEGIN
  l_key := dbms_crypto.randombytes(l_key_len);

  enc_val := dbms_crypto.encrypt(
  utl_i18n.string_to_raw('tata titi toto', 'AL32UTF8'),
  l_mod, l_key);

  dbms_output.put_line(enc_val);
END;
/

Or just with a select:

select dbms_crypto.encrypt(
         utl_i18n.string_to_raw('tata titi toto', 'AL32UTF8'),
         6 + 256 + 4096,
         dbms_crypto.randombytes(128/8)
       )
from dual

The 6 + 256 + 4096 represents dbms_crypto.ENCRYPT_AES128 + dbms_crypto.CHAIN_CBC + dbms_crypto.PAD_ZERO