Collision Rate With NTLMv2 Hashing Technique In Windows

Im doing a research assignment at Uni where i am investigating hash functions.

With SHA1 and (from what i can understand) all hash techniques there is (incredibly rarely) hash c开发者_如何学Collisions. See here

Can anyove give me a figure of how likely a hashing collision occurs in NTLMv2 (used in windows 7)?

Thanks

Tom

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NTLMv2 is an hmac-md5 implementation. It should be noted that collisions do not affect HMACs. In order for an attacker to generate a collision for an md5 has a complexity of (2^24.1)/2=2^23.1, however i don't believe such an attack can be mounted against NTLMv2. So iI believe the answer is (2^128)/2=2^127. This number is thinking of md5 as an ideal message digest function, and of course no such ideal function can exist.

Division by 2 is done to account for the birthday paradox.