Php/docs/intro.ssdeep
From Get docs
ssdeep is a utility for creating and comparing fuzzy hashes or [http://dfrws.org/2006/proceedings/12-Kornblum.pdf » context-triggered piecewise hashing].
Fuzzy hashing can match signatures which have "...sequences of identical bytes in the same order, although bytes in between these sequences may be different in both content and length". ([http://ssdeep.sourceforge.net » ssdeep project page])
This extension provides functions for creating and comparing fuzzy hashes.
