Security of cryptographic hash functions: Difference between revisions

Revision as of 07:07, 13 September 2017

Revision as of 21:48, 21 September 2018

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The second approach is theoretical and is based on the [[computational complexity theory]]. If problem A is hard, there exists a formal [[Reduction (complexity)|security reduction]] from a problem which is widely considered unsolvable in [[polynomial time]], such as [[integer factorization]] problem or [[discrete logarithm]] problem.

However, non-existence of a polynomial time algorithm does not automatically ensure that the system is secure. The difficulty of a problem also depends on its size. For example, [[RSA public key cryptography]] relies on the difficulty of [[integer factorization]]. However, it is considered secure only with keys that are at least 10242048 bits large.

==Cryptographic hash functions==