Bugtraq mailing list archives
Re: /dev/random is probably not
From: Jack Lloyd <lloyd () randombit net>
Date: Tue, 5 Jul 2005 12:45:14 -0400
On Sun, Jul 03, 2005 at 12:39:30PM -0700, Zow Terry Brugger wrote:
It's been a while since I looked at the /dev/random design on Linux (probably the early 2.4 days), however one thing that was quite clear was that they did not use any network I/O as entropy sources because an attacker, particularly one that already had control of other machines on the same LAN segment, could have a high degree of control over that source. I would be most interested if that has changed since the last time I looked at it.
ISTR that grsecurity has toggles that enable gathering entropy from network traffic. Assuming the PRNG is any good, it shouldn't matter if an attacker can manipulate such timings, because (by definition) a good PRNG will still behave correctly even if an attacker does feed it lots of deliberately bad data (as long as the PRNG also has been fed with a sufficient amount of unguessable 'good' input as well, of course). [...]
Windows family OSs.All I can observe here is that F-secure SSH still (at least the most recent version I've used) collects its own entropy when running on Win2K, which indicates to me that either they want to operate the same on all Windows versions (as memory serves, Win95/98 does not have a RNG), or that Win2k does not have a suitable RNG.
Only Win95 pre OSR2 is missing CryptoAPI (and specifically CryptGenRandom). However, it's my understanding that early versions of CryptGenRandom were not that great. -Jack
Current thread:
- Re: /dev/random is probably not, (continued)
- Re: /dev/random is probably not Thomas (Jul 06)
- Re: /dev/random is probably not Kai Howells (Jul 08)
- Re: /dev/random is probably not Stefan Bethke (Jul 08)
- Re: /dev/random is probably not Francesco Messineo (Jul 12)
- Re: /dev/random is probably not Zow (Jul 04)
- Re: /dev/random is probably not Anton Ivanov (Jul 05)
- Re: /dev/random is probably not devnull (Jul 06)
- RE: /dev/random is probably not David Schwartz (Jul 05)
- Re: /dev/random is probably not Glynn Clements (Jul 05)
- Re: /dev/random is probably not ChayoteMu (Jul 06)
- Re: /dev/random is probably not Jack Lloyd (Jul 05)
- Re: /dev/random is probably not Alexey Toptygin (Jul 06)
- Re: /dev/random is probably not Chris Kuethe (Jul 06)
- Re: /dev/random is probably not Thomas (Jul 06)
- RE: /dev/random is probably not David Schwartz (Jul 08)