Re: [PHP] Secure DB Systems - How to

> Keeping the system administrator from seeing the data while making it
> searchable is difficult. To do this you need to encrypt the data on
> the client side using a key the client has (and this key has to be
> protected from loss) and the only searches you can do are equality
> searches using a hash or encrypted value.

You can also perform regex searches.

Here is an example to get you started:

CREATE TABLE crypto (
id SERIAL PRIMARY KEY,
title VARCHAR(50),
crypted_content BYTEA
);

INSERT INTO crypto VALUES (1,'test1',encrypt_iv('daniel','fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'),'aes'));
INSERT INTO crypto VALUES (2,'test2',encrypt_iv('test','fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'),'aes'));
INSERT INTO crypto VALUES (3,'test3',encrypt_iv('struck','fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'),'aes'));

SELECT *,decrypt_iv(crypted_content, 'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'), 'aes') FROM crypto;

-- equality search
SELECT *,decrypt_iv(crypted_content,'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'),'aes')
FROM crypto WHERE decrypt_iv(crypted_content, 'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'), 'aes')='struck';

-- regex search
SELECT *,decrypt_iv(crypted_content,'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'),'aes')
FROM crypto WHERE encode(decrypt_iv(crypted_content, 'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g==','base64'), 'aes'),'escape')
~* 'daniel';

"fooz" is the password and "9MlPeZtpuxKo5m4O4+pd4g==" is the IV (initialization vector) stored in base64 format. I choose base64 because it is more convenient to create queries with it.

In the real database I do use a different IV for every row, so I do also store the IV with the row.
In my case I do generate the IV by PHP with /dev/urandom as a random source.

Greetings,

Daniel Struck

--
Retrovirology Laboratory Luxembourg
Centre Hospitalier de Luxembourg
4, rue E. Barblé
L-1210 Luxembourg

phone: +352-44116105
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