create or replace procedure encr ( input_string varchar2 ) as
   encrypted_raw      RAW (2000);             -- stores encrypted binary text
   num_key_bytes      NUMBER := 192/8;        -- key length 256 bits (32 bytes)
   key_bytes_raw      RAW (32);               -- stores 256-bit encryption key
   encryption_type    PLS_INTEGER :=          -- total encryption type
                            DBMS_CRYPTO.ENCRYPT_AES192
                          + DBMS_CRYPTO.CHAIN_CBC
                          + DBMS_CRYPTO.PAD_PKCS5;
   
BEGIN
   DBMS_OUTPUT.PUT_LINE ( 'Original string: ' || input_string);
   key_bytes_raw := DBMS_CRYPTO.RANDOMBYTES (num_key_bytes);
   encrypted_raw := DBMS_CRYPTO.ENCRYPT
      (
         src => UTL_I18N.STRING_TO_RAW (input_string,  'AL32UTF8'),
         typ => encryption_type,
         key => key_bytes_raw,
         iv  => null
      );
 
   DBMS_OUTPUT.PUT_LINE ('Encrypted raw len: ' || lengthb(encrypted_raw)); 
end encr;
/

exec encr('1');

Original string: 1
Encrypted raw len: 32

exec encr('123456789ABCDEF');

Original string: 123456789ABCDEF
Encrypted raw len: 32

exec encr('123456789ABCDEF0');

Original string: 123456789ABCDEF0
Encrypted raw len: 64

exec encr('123456789ABCDEF0123456789ABCDEF0');

Original string: 123456789ABCDEF0123456789ABCDEF0
Encrypted raw len: 96