How to encrypt nvarchar column in oracle? - oracle

Question

I have a table containing nvarchar datatype columns (contains text in different languages). I want to encrypt data before inserting into table and decrypt the same while fetching records.
Please suggest how i can achieve this.
Encryption and decryption should be done through a private key.
Hoping, my question is clear. Please confirm if i need to provide more information.

Answer 1

Note that it is probably wiser to crypt and decrypt your data directly in your application rather than in the database.
You can use Oracle's DBMS_CRYPTO package. There is an example in the middle of the documentation page.
First you need to make a package to access the cipher type from SQL expression. Let's say you want AES256 in CBC mode with padding:
CREATE PACKAGE pkg_so_42979606
AS
FUNCTION cipher_type RETURN PLS_INTEGER;
END pkg_so_42979606;
/
CREATE PACKAGE BODY pkg_so_42979606
AS
ctype CONSTANT PLS_INTEGER := DBMS_CRYPTO.ENCRYPT_AES256
+ DBMS_CRYPTO.CHAIN_CBC
+ DBMS_CRYPTO.PAD_PKCS5;
FUNCTION cipher_type RETURN PLS_INTEGER
IS
BEGIN
RETURN ctype;
END;
END pkg_so_42979606;
/
Then you will need a key. You can ask Oracle to generate one. To easily handle it I'll move it in Base64. Let's draw one:
DECLARE
key_bytes_raw RAW(32);
key_char NVARCHAR2(64);
BEGIN
key_bytes_raw := DBMS_CRYPTO.RANDOMBYTES(32);
key_char := UTL_I18N.RAW_TO_CHAR(UTL_ENCODE.BASE64_ENCODE(key_bytes_raw), 'AL32UTF8');
DBMS_OUTPUT.PUT_LINE('Key: ' || key_char);
END;
/
Key: pMV3D4xhyfNxp3YyfLWzAErGcKkIjK3X6uc/WIeVTls=
Thus the cipher key I'll use is pMV3D4xhyfNxp3YyfLWzAErGcKkIjK3X6uc/WIeVTls=.
Now I'll use a test table
CREATE TABLE so_42979606 (
id NUMBER PRIMARY KEY,
data NVARCHAR2(2000));
You can insert encrypted data:
INSERT INTO so_42979606
VALUES (1,
DBMS_CRYPTO.ENCRYPT(UTL_I18N.STRING_TO_RAW('My clear data', 'AL32UTF8'),
pkg_so_42979606.cipher_type(),
UTL_ENCODE.BASE64_DECODE(UTL_I18N.STRING_TO_RAW('pMV3D4xhyfNxp3YyfLWzAErGcKkIjK3X6uc/WIeVTls=', 'AL32UTF8'))));
And retrieve the encrypted data in clear.
SELECT id, UTL_I18N.RAW_TO_NCHAR(DBMS_CRYPTO.DECRYPT(data,
pkg_so_42979606.cipher_type(),
UTL_ENCODE.BASE64_DECODE(UTL_I18N.STRING_TO_RAW('pMV3D4xhyfNxp3YyfLWzAErGcKkIjK3X6uc/WIeVTls=', 'AL32UTF8'))),
'AL32UTF8') data
FROM so_42979606;
ID DATA
-- ----------------------
1 My clear data