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Re: RC4 and Lotus Notes
From: Derek Atkins <derek () ihtfp com>
Date: 21 Apr 2003 11:07:59 -0400
While RC4 does have some weaknesses in its key scheduling, that alone does not make it a weak cipher. Indeed, the WEP break was not due solely to RC4 -- most of the problem was that WEP used RC4 incorrectly. It is perfectly reasonable to use RC4-256 (are you SURE it's using a 256-bit key?) in a "secure" application. You just need to be careful to: a) use real, unique IVs b) use different, unique, random keys in both directions c) discard the first N bytes of the cipher (IIRC 256-1024) d) never.. EVER re-use a key WEP's problem was that it violated all four of these rules, which is why it was broken. The fact that WEP's IV was only 24 bits didn't help -- 24 bits wraps around pretty quickly on a busy network. Worse, the IV gets re-set if the AP gets rebooted. So, don't fear RC4 just because it's RC4.. Fear RC4 because most people don't know how to _use_ it properly. :) -derek aliver () xexil com writes:
While developing something boring using the Lotus C API for Linux. I noticed while using valgrind that functions like NSFNoteDecrypt() and NSFNoteIsSignedOrSealed() are still making use of RC4 encryption with a 256 bit key even when I use "strong" encryption settings in it's lame windows MegaGUI. IIRC, RC4 is known to have some weaknesses in it's key scheduling that have yielded some interesting results (WEP, Winnt, etc..). I'm pretty sure my libnotes.so is up to date. Am I misinformed about the choice of crypto in Lotus Notes? Anyone know of plans to change this? I guess it doesn't matter since nobody is masochistic enough to work on a brute forcer for something as nasty as LN. It's what you call "security-through-being-so-disgusting-no-one-will-play-with-you" or "the hagfish method." aliver _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
-- Derek Atkins Computer and Internet Security Consultant derek () ihtfp com www.ihtfp.com _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- RC4 and Lotus Notes aliver (Apr 21)
- Re: RC4 and Lotus Notes HAYAKAWA Hitoshi (Apr 21)
- Re: RC4 and Lotus Notes Derek Atkins (Apr 21)
- <Possible follow-ups>
- Re: RC4 and Lotus Notes aliver (Apr 21)