Open Source Encryption

From: Pat (patkay_156_at_yahoo.co.uk)
Date: 05/05/04 

Date: 5 May 2004 08:33:53 -0700

Hi,

Does anyone here know of any Open Source software that can do anything
similar to this product:

http://www.securstar.com/products_drivecryptpp.php

i.e. Provide real-time "Pre-Boot authentication" encryption/decryption
to an entire disk including the OS?

Thanks for any suggestions.