Re: Crypting files with Ada

[Jacob Sparre Andersen <sparre@nbi.dk>]

Preben Randhol wrote:

> I don't know. That is sth I have to find out. The problem is that if you
> simply delete a file in say Windows or Linux you don't rease it you only
> delete the link. So unless the OS has overwritten the place the file
> occupied with new files one can recover it.

Yes.

> I guess one could change every byte in the file with 0 and then write
> the file again before deleting it.

This would not necessarily be enough. According to a paper 
by Peter Gutmann, you ought to overwrite the file 35 times 
with different bit patterns. You can find an implementation 
of this here:

    http://www.linux-kurser.dk/secure_harddisk_eraser.html

(it's written in C)

Jacob
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