'Trend Micro' provides an open source library https://github.com/trendmicro/tlsh/ for local sensitivity hashing. Methods are provided to compute and compare hashes from character/byte streams.
Jonathan Oliver, Chun Cheng and Yanggui Chen, "TLSH - A Locality Sensitive Hash" 4th Cybercrime and Trustworthy Computing Workshop, Sydney, November 2013
Jonathan Oliver, Scott Forman and Chun Cheng, "Using Randomization to Attack Similarity Digests" Applications and Techniques in Information Security. Springer Berlin Heidelberg, 2014. 199-210.
Jonathan Oliver and Jayson Pryde's Trend Micro Blog Post