Added SUBSET_KEY description

Author: nindanaoto

CMakeLists.txt

@@ -18,6 +18,7 @@ option(USE_CONCRETE "Use the parameter set proposed in CONCRETE" OFF)
 option(USE_TFHE_RS "Use the parameter set proposed in TFHE-rs" OFF)
 option(USE_TERNARY "Use ternary secret keys" OFF)
 option(USE_COMPRESS "Use compressed ciphertexts" OFF)
+option(USE_SUBSET_KEY "Use subset key" OFF)
 
 option(USE_TERNARY_CMUX "Use ternary cmux" OFF)
 option(USE_KEY_BUNDLE "Use key bundle algorithm" OFF)

README.md

@@ -1,6 +1,6 @@
 [![Test](https://github.com/virtualsecureplatform/TFHEpp/actions/workflows/test.yml/badge.svg)](https://github.com/virtualsecureplatform/TFHEpp/actions/workflows/test.yml)
 # TFHEpp
-TFHEpp is full Scracthed pure C++ Ver. of TFHE. TFHEpp is slightly(about 10%) faster than original [TFHE implementation](https://github.com/tfhe/tfhe). In addition to that, THFEpp supports [Circuit Bootstrapping](https://eprint.iacr.org/2018/421), [Programable Boootstrapping many LUT](https://eprint.iacr.org/2021/729), and [Modifed Chen's Packing](https://eprint.iacr.org/2024/1318) (We call it as annihilate key switching in our code). 
+TFHEpp is full Scracthed pure C++ Ver. of TFHE. TFHEpp is slightly(about 10%) faster than original [TFHE implementation](https://github.com/tfhe/tfhe). In addition to that, THFEpp supports [Circuit Bootstrapping](https://eprint.iacr.org/2018/421), [Programable Boootstrapping many LUT](https://eprint.iacr.org/2021/729), [Partial Key](https://eprint.iacr.org/2023/979) (Named as subset key in the code),and [Modifed Chen's Packing](https://eprint.iacr.org/2024/1318) (We call it as annihilate key switching in our code). 
 We also includes partial support for B/FV, written in include/bfv++.hpp.
 TFHEpp depends on AVX2 because we use SPQLIOS FMA. If you want run TFHEpp without AVX2, see spqlios++ branch. It include pure C++ implementation of SPQLIOS as header only library, but slow.
 

src/key.cpp

@@ -16,6 +16,9 @@ lweKey::lweKey()
     for (typename lvlhalfparam::T &i : lvlhalf) i = lvlhalfgen(generator);
     for (typename lvl1param::T &i : lvl1) i = lvl1gen(generator);
     for (typename lvl2param::T &i : lvl2) i = lvl2gen(generator);
+    #ifdef USE_SUBSET_KEY
+    for(int i = 0; i < lvl1param::k*lvl1param::n; i++) lvl2[i] = lvl1[i];
+    #endif
 }
 
 template <class P>