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Issue 8.4

FEATURE

REALScience: Making Hash

An introduction to hash functions

Issue: 8.4 (May/June 2010)
Author: JC Cruz
Author Bio: JC is a freelance technical writer living in British Columbia. He writes for various publications, pokes around with Cocoa, Python and REALbasic, and spends time with his nephew. He can be reached at: anarakisware@gmail.com
Article Description: No description available.
Article Length (in bytes): 38,276
Starting Page Number: 31
Article Number: 8411
Resource File(s):

Download Icon 8411.zip Updated: 2010-05-03 18:55:45

Related Web Link(s):

http://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function
http://sites.google.com/site/Murmur
http://burtleburtle.net/bob/hash/doobs.html
http://en.literateprograms.org/Hash_function_comparison_%28C%2C_sh%29
http://www.eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
http://en.wikipedia.org/wiki/http
http://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function
http://en.wikipedia.org/wiki/Murmur
http://en.wikipedia.org/wiki/S-box

Excerpt of article text...

Welcome back to another round of REALScience. Today, we journey into that poorly understood field of hash functions. We begin by understanding what a hash function is and what benefits it brings to our code toolbox. Then we study the parts that make up a basic function. Next, we survey a handful of general-purpose functions and learn how they work. We then subject these functions to a series of standard tests and compare the results against REALbasic's built-in hash. So get yourselves a cup of hot brew and let us commence.

The Theory of Hash

Hash functions are part of a group of algorithms known as one-way functions. Like many functions, they convert data from one form to another. The reverse, however, is either too difficult, if not nigh impossible to do. Examples of other one-way functions include checksum routines, ciphers, and random number generators.

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