Date: Tue, 13 Jul 2004 11:35:57 +0200
From: Daniel Struck <struck.d@retrovirology.lu>
To: Bruno Wolff III <bruno@wolff.to>
Cc: Sarah Tanembaum <sarahtanembaum@yahoo.com>,
	pgsql-php@postgresql.org, pgsql-admin@postgresql.org,
	pgsql-hackers-win32@postgresql.org, pgadmin-support@postgresql.org,
	pgsql-sql@postgresql.org
Subject: Re: [PHP] Secure DB Systems - How to
Message-Id: <20040713113557.31e9d6dc@localhost>
In-Reply-To: <20040709152722.GA20935@wolff.to>
References: <ccjra4$pgl$1@sea.gmane.org>
	<20040709152722.GA20935@wolff.to>
Organization: gwia.inf.chl.lu
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-15
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> 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('9M=
lPeZtpuxKo5m4O4+pd4g=3D=3D','base64'),'aes'));
INSERT INTO  crypto VALUES (2,'test2',encrypt_iv('test','fooz',decode('9MlP=
eZtpuxKo5m4O4+pd4g=3D=3D','base64'),'aes'));
INSERT INTO  crypto VALUES (3,'test3',encrypt_iv('struck','fooz',decode('9M=
lPeZtpuxKo5m4O4+pd4g=3D=3D','base64'),'aes'));

SELECT *,decrypt_iv(crypted_content, 'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g=
=3D=3D','base64'), 'aes') FROM crypto;

-- equality search
SELECT *,decrypt_iv(crypted_content,'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g=
=3D=3D','base64'),'aes')
FROM crypto WHERE decrypt_iv(crypted_content, 'fooz',decode('9MlPeZtpuxKo5m=
4O4+pd4g=3D=3D','base64'), 'aes')=3D'struck';

-- regex search
SELECT *,decrypt_iv(crypted_content,'fooz',decode('9MlPeZtpuxKo5m4O4+pd4g=
=3D=3D','base64'),'aes')
FROM crypto WHERE encode(decrypt_iv(crypted_content, 'fooz',decode('9MlPeZt=
puxKo5m4O4+pd4g=3D=3D','base64'), 'aes'),'escape')
~* 'daniel';


"fooz" is the password and "9MlPeZtpuxKo5m4O4+pd4g=3D=3D" is the IV (initia=
lization vector) stored in base64 format. I choose base64 because it is mor=
e convenient to create queries with it.

In the real database I do use a different IV for every row, so I do also st=
ore 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

--=20
Retrovirology Laboratory Luxembourg
Centre Hospitalier de Luxembourg
4, rue E. Barbl=E9
L-1210 Luxembourg

phone: +352-44116105
fax:   +352-44116113
web: http://www.retrovirology.lu
e-mail: struck.d@retrovirology.lu