Frankk at 04:33, 27 October 2005

2005-10-27T04:33:28Z

← Older revision		Revision as of 21:33, 26 October 2005
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	The desirable property of a [[One way hash]] algorithm is that for any given input, the output is unique. Given that the hash output is almost always smaller than the input, this property can't be achieved completely. When two sets of input data result in the same hash output, it is called a [[hash collision]].		The desirable property of a [[One way hash]] algorithm is that for any given input, the output is unique. Given that the hash output is almost always smaller than the input, this property can't be achieved completely. When two sets of input data result in the same hash output, it is called a [[hash collision]].

	Hash collisions aren't always a problem. Some techniques, like [[hashcash]], rely on finding collisions as a "proof of work". The problems arise when similar data sets collide. This is the basis of the [[MD5]] collision paper presented at Crypto 2004. Further research has produced a method of creating quite similar documents that have the same [[MD5]] hash value. When the two documents are, for example, slightly different versions of a contract, and the [[MD5]] hash value is used to attest that the original document has not been altered, the [[hash collision]] problem becomes obvious.		Hash collisions aren't always a problem. Some techniques, like [[hashcash]], rely on finding collisions as a "proof of work". The problems arise when similar data sets collide. This is the basis of the [http://eprint.iacr.org/2004/199.pdf MD5 collision paper] presented at Crypto 2004. Further research has produced a method of creating quite similar documents that have the same [[MD5]] hash value. When the two documents are, for example, slightly different versions of a contract, and the [[MD5]] hash value is used to attest that the original document has not been altered, the [[hash collision]] problem becomes obvious.

Roy at 04:49, 10 October 2005

2005-10-10T04:49:04Z

New page

The desirable property of a [[One way hash]] algorithm is that for any given input, the output is unique. Given that the hash output is almost always smaller than the input, this property can't be achieved completely. When two sets of input data result in the same hash output, it is called a [[hash collision]].

Hash collisions aren't always a problem. Some techniques, like [[hashcash]], rely on finding collisions as a "proof of work". The problems arise when similar data sets collide. This is the basis of the [[MD5]] collision paper presented at Crypto 2004. Further research has produced a method of creating quite similar documents that have the same [[MD5]] hash value. When the two documents are, for example, slightly different versions of a contract, and the [[MD5]] hash value is used to attest that the original document has not been altered, the [[hash collision]] problem becomes obvious.

Hash collision - Revision history

Frankk at 04:33, 27 October 2005

Roy at 04:49, 10 October 2005