Overview#

A Cryptographic Hash Function (One-Way Hash Function OWHF) is a Hash Function with some additional MUST have properties: If a Cryptographic Hash Function can NOT meet these requirements, the resulting hash is considered Cryptographically Weak.

Most Common Cryptographic Hash Function#

ThŽe most commonly used Cryptographic Hash Function function today (2015-03-15) is SHA-1, which has output of 160 bits. (see SHAttered and SHA-1 Deprecation)

Strength of Cryptographic Hash Function#

Unlike with Ciphers, the strength of a Cryptographic Hash Function doesn’t equal the Hash length. Because of the Birthday Paradox (a well-known problem in probability theory), the strength of a Cryptographic Hash Function is at most one half of the Hash length.

The harder it is to compute raises the Level Of Assurance.

Note that unlike hardness in most of complexity theory (e.g., NP-hardness), "hard" in the context of one-way functions refers to the Computational Hardness Assumption rather than worst-case hardness.

The existence of "pure" one-way functions is an open conjecture. for more information see Wikipedia:One-way_function

More Information#

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« This page (revision-25) was last changed on 31-Jul-2017 09:39 by jim