From: frantz@netcom.com (Bill Frantz)
Date: Fri, 27 Oct 1995 15:28:51 +0800
To: cypherpunks@toad.com
Subject: Re: Linux security issues
Message-ID: <199510270552.WAA17904@netcom7.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


At  1:23 10/26/95 -0500, Aleph One wrote:
>         I dont see what this has to do with Linux. The question should
>be does the PGP pass phrase ever apper in a swap partition/file.

Actually keeping the pass phrase out of swap space is fairly easy (although
I havn't looked at the PGP code to see if it actually does this).  Read the
pass phrase in raw mode, one character at a time and convert it one
character at a time to the decryption key for the private RSA key.  Then
the OS doesn't need to buffer the whole line, either in kernel space or in
user space.

However, the pass phrase is not the only dangerous information. 
Intermediate forms used for decrypting the RSA private keys, and the
decrypted RSA private keys also have to be protected.  The logic of PGP
requires that it keep at least one of these around for a long time, so it
will probably be written to swap space.

N.B. This problem affects all virtual memory operation systems.  I can
think of the Unix/Linux family, MacOS with virtual memory turned on, and
most mainframe OSs (e.g. IBM's VM/ESA).


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Bill Frantz                   Periwinkle  --  Computer Consulting
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