Re: Insecure Hash Algorithms (MD5) and NTLMv2

[Daniel Miessler <daniel () dmiessler com>]

On Nov 2, 2005, at 1:54 AM, Steve Friedl wrote:

> The only weakness that's really in the air is Collision Resistance,
> where we can produce two inputs with the same hash. This is of only
> minor concern in a practical sense, though it certainly does mean that
> blood is in the water and sharks are circling.

Exactly my point. To put it another way, the ability to create  
collisions has no bearing on the ability of an attacker to find  
unknown inputs to known hashes. Or, in the technical terms that you  
highlighted, attacks against collision resistance don't necessarily  
lead to attacks on preimage resistance.

Hence, for the purposes of breaking hashes to discover passwords,  
NTLMv2 is not significantly affected by the recently discovered  
weaknesses in the MD5 hashing algorithm.

--
Daniel R. Miessler
M: daniel () dmiessler com
W: http://dmiessler.com
G: 0x316BC712

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