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An Implementation of homomorphic encryption
C++ CMake Objective-C Makefile C Dockerfile
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Latest commit 7427ed3 Aug 19, 2019


August 2019: Improved noise managemebt in HElib. Better and more robust bootstrapping algorithm. Ubuntu 18.04 Docker image with HElib and its dependencies. See install instructions in

July 2019: Added new bootstrapping and PGFFT tests.

June 2019: Added implementation of PGFFT to replace Armadillo for FFTs in the CKKS scheme. See comments in PGFFT.h for more information.

May 2019: CKKS bug fixes and fixed compiler warnings.

April 2019: Moved the HElib repository on github from shaih/HElib to HomEnc/HElib. Introduced HElib-specific exceptions, replaced C assert, NTL Error and std::exception to use HElib-specific assertions that throw the new exceptions. See comments in assertions.h and exceptions.h for usage information.

March 2019: Introduced new test framework (google test), documented in Previous framework will be deprecated. Added a cmake build script for building HElib and dependencies, documented in Added an example program, see example program.

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

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 outputs 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 implemented 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.

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