md5 and large files

Kirk Job-Sluder kirk-news at jobsluder.net
Wed Oct 20 01:06:48 CEST 2004


Nelson Minar wrote:
> Tobias Pfeiffer <me at privacy.net> writes:
> 
>>I have no clue about what the md5 algorithm works like, but I'd
>>think one could prove that with an number large enough, every hash
>>occurs twice. At last, md5 is not random.
> 
> 
> MD5 is random, and a very strong form of random at that. But yes,
> the same 128 bit hash will occur for different inputs. The trick is
> that it's nearly impossible to construct an input that produces a
> given hash, or even to produce collisions. For more, see here:
>   http://en.wikipedia.org/wiki/Md5


Actually, it turns out to be much easier than it should be to create 
collisions. It is possible that this analytical attack might lead to 
broader attacks in the future.  This is one big reason to transition 
from MD5 to SHA1.



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