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Mar 23rd, 2009
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Md5 Question

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A friend of mine an i were wondering the following

If there is really a one in 20 million chance of and two files having the same MD5 hash

in theory, would it not be possible to recreate a file from the MD5 hash itself?

I understand the time involved in doing this through the "rainbow tables" method, not to mention the processing power.

but with new processors coming out with 8 cores or so....

you see where this is going...
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Merlin33069 is offline Offline
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Mar 30th, 2009
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Re: Md5 Question

Quote ...
in theory, would it not be possible to recreate a file from the MD5 hash itself?
No. Hashing cant do that.
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jbennet is offline Offline
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Re: Md5 Question

ay, still would be cool
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Re: Md5 Question

its not possible though

thats not what a hash is. A hash is a totally arbitrary thing, its meaningless without a context with which to apply it to.

if we are going to be really technical, an MD5Sum isnt a type of hash at all, its a checksum, but the same thinking applies
Last edited by jbennet; Mar 30th, 2009 at 11:41 pm.
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Re: Md5 Question

Um, yes, it is a hash. Is hash not a synonym of checksum?
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Re: Md5 Question

no hashes have a completely different meaning when used in the context of databases

http://en.wikipedia.org/wiki/Hash_function

The first few paragraphs of this explain it
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Re: Md5 Question

The differences explained there are a pedantic wikipedian classification system. Hashes, checksums, and cryptographic hashes are all the same thing and are all designed for the same general purpose. The only difference between a "good hash function" and a "good checksum function" and such is that different traits are valued more intensely.
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