Niko's Project Corner

Hash-based commitment schemes without a computer

An in­ter­est­ing ques­tion was posted to crypto.stack­ex­change.com: "Is there a sim­ple hash func­tion that one can com­pute with­out a com­puter?" Here are three pro­posed al­go­rithms based on Zo­brist hash­ing, RC4 and A5/1. These should be reasonably secure even against attacks with a calculator, except the one based on Zobrist hashing (but I don't know how to prove or dis-prove this claim). These constructs are especially well suited for com­mit­ment schemes.

Very fuzzy searching with CUDA

This is an al­ter­na­tive an­swer to the ques­tion I en­coun­tered at Stack Over­flow about fuzzy search­ing of hashes on Elas­tic­search. My orig­inal an­swer used lo­cal­ity-sen­si­tive hash­ing. Su­pe­rior speed and sim­ple im­ple­men­ta­tion were gained by us­ing nVidia's CUDA via Thrust li­brary.

Very fuzzy searching with Elasticsearch

I en­coun­tered an in­ter­est­ing ques­tion at Stack Over­flow about fuzzy search­ing of hashes on Elas­tic­search and de­cided to give it a go. It has na­tive sup­port for fuzzy text searches but due to per­for­mance rea­sons it only sup­ports an edit dis­tance up-to 2. In this con­text the max­imum al­lowed dis­tance was eight so an al­ter­na­tive so­lu­tion was needed. A so­lu­tion was found from lo­cal­ity-sen­si­tive hash­ing.