January 2019: Multiple changes: CKKS support, new modulus-chain implementation, better noise management, etc. Documented in changes.md

March 2018: Re-implementation of homomorphic linear transformations, featuring speedups of 15x to 75x.

Dec 2017-Jan 2018: Added some routines for addition/multiplication and comparisons of integers in binary representation, and for homomorphic table lookup. See the supported interfaces in binaryArith.h, binaryCompare.h, and tableLookup.h. Some examples are in Test_binaryArith.cpp, Test_binaryCompare.cpp, and Test_tableLookup.cpp.

The inputs and putputs to the new routines are logically vectors of Ctxt objects (one Ctxt per bit in the binary representation). These vectors are wrapped by the new CtPtrs wrapper (see CtPtrs.h and the underlying PtrsVector.h and PtrsMatrix.h). Hence the same logic will work for any type of input that can be mapped logically to arrays of Ctxts, as long as one can wrap them with the same wrapper class. In particular, we implementated wrappers for std::vector<Ctxt>, std::vector<Ctxt*>, NTL::Vec<Ctxt> and NTL::Vec<Ctxt*>.

HElib is a software library that implements homomorphic encryption (HE). Currently available is an implementation of the Brakerski-Gentry-Vaikuntanathan (BGV) scheme, along with many optimizations to make homomorphic evaluation runs faster, focusing mostly on effective use of the Smart-Vercauteren ciphertext packing techniques and the Gentry-Halevi-Smart optimizations. See this report for a description of a few of the algorithms using in this library. Starting December 2014, the library also includes bootstrapping.

At its present state, this library is mostly meant for researchers working on HE and its uses. Also currently it is fairly low-level, and is best thought of as "assembly language for HE". That is, it provides low-level routines (set, add, multiply, shift, etc.), with as much access to optimizations as we can give. Hopefully in time we will be able to provide higher-level routines.

This library is written in C++ and uses the NTL mathematical library (version 10.0.0 or higher). As of March 2015, it also supports multi-threading. HElib is distributed under the terms of the Apache License v2.0. For more information see the GitHub Pages.