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Re: MD5 collisions found - alternative?

On Thu, 26 Aug 2004, Almut Behrens wrote:

On Wed, Aug 25, 2004 at 01:15:13AM -0400, Hubert Chan wrote:
... So the only useful notion of oneway is that the hash is not easily invertible (i.e. you can't easily find some string that produces a given hash value).

So, if you can somehow come up with an input string (except by brute force search), which computes to some given hash, that means you inverted the function, and it's thus not oneway -- nothing more and nothing less. It has nothing to do with whether there exists some theoretic backward mapping from output to input that would uniquely retrieve the string originally used to compute the hash.


for those who are interested in this topic, I can recommend the handbook of applied cryptography. the book's chapters are available for free download at http://www.cacr.math.uwaterloo.ca/hac/ chapter 9 focuses on cryptographic hash functions. the first chapter gives an excellent general overview of cryptographic aspects in human readable form.

Thanks again everyone for taking the time.

you are welcome,


expert in just too late deliveries and applied cryptography
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