[Dshield] Crypto Question

Jon Kibler Jon.Kibler at aset.com
Wed Mar 4 01:10:37 GMT 2009

Hash: SHA1


Is there a good crypto mailing list for "manager" level questions? The
Security Focus crypto list appears to be dead. Where would be a more
appropriate place to ask the follow question?

I am having a surreal conversation with a client's auditors regarding
MD5, and I need some advice about the issue. I understand the basic
issues with MD5, but I am having a hard time conveying the issue to the
client in a way that moves the discussion of the issue forward.

It all started with a clueless regulatory auditor finding that the
client's Linux servers used MD5 password hashes. The auditor told the
client that regulations prohibit the use of MD5 and that they had to use
at least SHA-1 hashes.

I explained to the client that SHA-1 was not an option. They could have
DES, which was highly insecure, or they could have the Linux standard
MD5, which was highly secure (assuming reasonable passwords), or they
could have BlowFish, which would cost them a lot of money to implement
and would give them a ridiculous degree of password security.

They contacted the auditors, whose response was "MD5 cannot be used
because MD5 is broken, and BlowFish is not a recognized standard so it
cannot be used. Since DES is a standard and it is not broken that is
what you must use."

I tried to argue that was an assinie answer (but using more polite
phrasing), and got no where. I then tried some different tactics:

  Comment: The issue with MD5 was not with password hashing, rather it
was with MACs, and the issue was essentially irrelevant for password
  Response: Any and all uses of MD5 are prohibited.

  Q: If MD5 is broken, why do you allow it for IPSec?
  A: IPSec is not an MD5 algorithm.

  Q: If MD5 is broken, why do you allow it in the VoIP phones for SIP?
  A: SIP is not MD5.

  Q: Your standard says that SSL 2.x and SSL 3.x are allowable protocols
(but TLS is not!), and both use MD5, so why is SSL allowed?
  A: As long as the SSL certificates are not MD5, there is no use of MD5
by SSL.

Clearly, the auditors and/or regulators are clueless. If I can't win
this war, how can I at least bring this to a reasonable conclusion where
my customer has decent strength password hashing?

What would be a better list to ask this question on?


Jon K.
- --
Jon R. Kibler
Chief Technical Officer
Advanced Systems Engineering Technology, Inc.
Charleston, SC  USA
o: 843-849-8214
c: 843-224-2494
s: 843-564-4224

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