GNU bug report logs - #22202
24.5; SECURITY ISSUE -- Emacs Server vulnerable to random number generator attack on Windows systems

Previous Next

Full log

View this message in rfc822 format

From: Richard Copley <rcopley <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 22202 <at> debbugs.gnu.org, Demetrios Obenour <demetriobenour <at> gmail.com>, David Engster <deng <at> randomsample.de>
Subject: bug#22202: 24.5; SECURITY ISSUE -- Emacs Server vulnerable to random number generator attack on Windows systems
Date: Thu, 31 Dec 2015 19:49:42 +0000

>> That last patch would still improve matters. The user would have
>> to be publishing the output of their PRNG to begin with in order
>> for the attacker to analyse it and guess the seed. (I don't know
>> how one could do that but that's no proof that it's impossible.)
>
>I don't even understand how that could be possible.

Me either, but that doesn't make it impossible. (There are articles
on the web demonstrating such feats, if you're interested.)

>> What Demetri has just described is what I would do.
>
>Now I'm confused: do what?

As I understand it: Provide a function callable from lisp that returns
a cryptographically secure sequence of random bytes, of a specified
length. Use that function to generate the server secret.

>We still need to support 'random' with an
>argument, so we cannot get rid of seeding a PRNG with a known value.
>And I didn't want to remove srandom.

Given the above, we could leave "random", etc., as they are, or we
could use a better PRNG and/or seed with system entropy. It would
no longer be tied up with this issue report.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.