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452 lines
16 KiB
452 lines
16 KiB
[](https://travis-ci.org/herumi/mcl)
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# mcl
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A portable and fast pairing-based cryptography library.
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# Abstract
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mcl is a library for pairing-based cryptography.
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The current version supports the optimal Ate pairing over BN curves and BLS12-381 curves.
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# News
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* (Break backward compatibility) libmcl_dy.a is renamed to libmcl.a
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* The option SHARE_BASENAME_SUF is removed
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* 2nd argument of `mclBn_init` is changed from `maxUnitSize` to `compiledTimeVar`, which must be `MCLBN_COMPILED_TIME_VAR`.
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* break backward compatibility of mapToGi for BLS12. A map-to-function for BN is used.
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If `MCL_USE_OLD_MAPTO_FOR_BLS12` is defined, then the old function is used, but this will be removed in the future.
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# Support architecture
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* x86-64 Windows + Visual Studio
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* x86, x86-64 Linux + gcc/clang
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* ARM Linux
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* ARM64 Linux
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* (maybe any platform to be supported by LLVM)
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* WebAssembly
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# Support curves
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p(z) = 36z^4 + 36z^3 + 24z^2 + 6z + 1.
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* BN254 ; a BN curve over the 254-bit prime p(z) where z = -(2^62 + 2^55 + 1).
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* BN\_SNARK1 ; a BN curve over a 254-bit prime p such that n := p + 1 - t has high 2-adicity.
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* BN381\_1 ; a BN curve over the 381-bit prime p(z) where z = -(2^94 + 2^76 + 2^72 + 1).
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* BN462 ; a BN curve over the 462-bit prime p(z) where z = 2^114 + 2^101 - 2^14 - 1.
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* BLS12\_381 ; [a BLS12-381 curve](https://blog.z.cash/new-snark-curve/)
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# Benchmark
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## The latest benchmark(2018/11/7)
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### Intel Core i7-6700 3.4GHz(Skylake), Ubuntu 18.04.1 LTS
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curveType | binary|clang-6.0.0|gcc-7.3.0|
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----------|--------------------|-----------|---------|
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BN254 | bin/bn\_test.exe| 882Kclk| 933Kclk|
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BLS12-381 | bin/bls12\_test.exe| 2290Kclk| 2630Kclk|
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### Intel Core i7-7700 3.6GHz(Kaby Lake), Ubuntu 18.04.1 LTS on Windows 10 Vmware
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curveType | binary|clang-6.0.0|gcc-7.3.0|
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----------|--------------------|-----------|---------|
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BN254 | bin/bn\_test.exe| 900Kclk| 954Kclk|
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BLS12-381 | bin/bls12\_test.exe| 2340Kclk| 2680Kclk|
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* now investigating the reason why gcc is slower than clang.
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## Higher-bit BN curve benchmark
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For JavaScript(WebAssembly), see [ID based encryption demo](https://herumi.github.io/mcl-wasm/ibe-demo.html).
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paramter | x64| Firefox on x64|Safari on iPhone7|
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-----------|-----|---------------|-----------------|
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BN254 | 0.25| 2.48| 4.78|
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BN381\_1 | 0.95| 7.91| 11.74|
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BN462 | 2.16| 14.73| 22.77|
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* x64 : 'Kaby Lake Core i7-7700(3.6GHz)'.
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* Firefox : 64-bit version 58.
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* iPhone7 : iOS 11.2.1.
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* BN254 is by `test/bn_test.cpp`.
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* BN381\_1 and BN462 are by `test/bn512_test.cpp`.
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* All the timings are given in ms(milliseconds).
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The other benchmark results are [bench.txt](bench.txt).
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## An old benchmark of a BN curve BN254(2016/12/25).
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* x64, x86 ; Inte Core i7-6700 3.4GHz(Skylake) upto 4GHz on Ubuntu 16.04.
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* `sudo cpufreq-set -g performance`
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* arm ; 900MHz quad-core ARM Cortex-A7 on Raspberry Pi2, Linux 4.4.11-v7+
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* arm64 ; 1.2GHz ARM Cortex-A53 [HiKey](http://www.96boards.org/product/hikey/)
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software | x64| x86| arm|arm64(msec)
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---------------------------------------------------------|------|-----|----|-----
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[ate-pairing](https://github.com/herumi/ate-pairing) | 0.21 | - | - | -
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mcl | 0.31 | 1.6 |22.6| 3.9
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[TEPLA](http://www.cipher.risk.tsukuba.ac.jp/tepla/) | 1.76 | 3.7 | 37 | 17.9
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[RELIC](https://github.com/relic-toolkit/relic) PRIME=254| 0.30 | 3.5 | 36 | -
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[MIRACL](https://github.com/miracl/MIRACL) ake12bnx | 4.2 | - | 78 | -
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[NEONabe](http://sandia.cs.cinvestav.mx/Site/NEONabe) | - | - | 16 | -
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* compile option for RELIC
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```
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cmake -DARITH=x64-asm-254 -DFP_PRIME=254 -DFPX_METHD="INTEG;INTEG;LAZYR" -DPP_METHD="LAZYR;OATEP"
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```
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# Installation Requirements
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* [GMP](https://gmplib.org/) and OpenSSL
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```
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apt install libgmp-dev libssl-dev
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```
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Create a working directory (e.g., work) and clone the following repositories.
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```
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mkdir work
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cd work
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git clone git://github.com/herumi/mcl
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git clone git://github.com/herumi/cybozulib_ext ; for only Windows
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```
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* Cybozulib\_ext is a prerequisite for running OpenSSL and GMP on VC (Visual C++).
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# (Option) Without GMP
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```
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make MCL_USE_GMP=0
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```
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Define `MCL_USE_VINT` before including `bn.hpp`
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# (Option) Without Openssl
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```
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make MCL_USE_OPENSSL=0
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```
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Define `MCL_DONT_USE_OPENSSL` before including `bn.hpp`
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# Build and test on x86-64 Linux, macOS, ARM and ARM64 Linux
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To make lib/libmcl.a and test it:
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```
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cd work/mcl
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make test
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```
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To benchmark a pairing:
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```
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bin/bn_test.exe
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```
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To make sample programs:
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```
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make sample
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```
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if you want to change compiler options for optimization, then set `CFLAGS_OPT_USER`.
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```
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make CLFAGS_OPT_USER="-O2"
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```
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## Build for 32-bit Linux
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Build openssl and gmp for 32-bit mode and install `<lib32>`
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```
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make ARCH=x86 CFLAGS_USER="-I <lib32>/include" LDFLAGS_USER="-L <lib32>/lib -Wl,-rpath,<lib32>/lib"
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```
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## Build for 64-bit Windows
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1) make static library and use it
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```
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mklib
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mk -s test\bn_c256_test.cpp
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bin\bn_c256_test.exe
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```
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2) make dynamic library and use it
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```
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mklib dll
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mk -d test\bn_c256_test.cpp
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bin\bn_c256_test.exe
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```
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open mcl.sln and build or if you have msbuild.exe
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```
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msbuild /p:Configuration=Release
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```
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## Build with cmake
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For Linux,
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```
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mkdir build
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cd build
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cmake ..
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make
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```
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For Visual Studio,
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```
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mkdir build
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cd build
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cmake .. -A x64
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msbuild mcl.sln /p:Configuration=Release /m
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```
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## Build for wasm(WebAssembly)
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mcl supports emcc (Emscripten) and `test/bn_test.cpp` runs on browers such as Firefox, Chrome and Edge.
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* [IBE on browser](https://herumi.github.io/mcl-wasm/ibe-demo.html)
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* [SHE on browser](https://herumi.github.io/she-wasm/she-demo.html)
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* [BLS signature on brower](https://herumi.github.io/bls-wasm/bls-demo.html)
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The timing of a pairing on `BN254` is 2.8msec on 64-bit Firefox with Skylake 3.4GHz.
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### Node.js
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* [mcl-wasm](https://www.npmjs.com/package/mcl-wasm) pairing library
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* [bls-wasm](https://www.npmjs.com/package/bls-wasm) BLS signature library
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* [she-wasm](https://www.npmjs.com/package/she-wasm) 2 Level Homomorphic Encryption library
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### SELinux
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mcl uses Xbyak JIT engine if it is available on x64 architecture,
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otherwise mcl uses a little slower functions generated by LLVM.
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The default mode enables SELinux security policy on CentOS, then JIT is disabled.
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```
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% sudo setenforce 1
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% getenforce
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Enforcing
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% bin/bn_test.exe
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JIT 0
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pairing 1.496Mclk
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finalExp 581.081Kclk
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% sudo setenforce 0
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% getenforce
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Permissive
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% bin/bn_test.exe
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JIT 1
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pairing 1.394Mclk
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finalExp 546.259Kclk
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```
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# Libraries
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* G1 and G2 is defined over Fp
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* The order of G1 and G2 is r.
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* Use `bn256.hpp` if only BN254 is used.
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## C++ library
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* libmcl.a ; static C++ library of mcl
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* libmcl.so ; shared C++ library of mcl
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* the default parameter of curveType is BN254
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header |support curveType |sizeof Fr|sizeof Fp|
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--------------|-------------------------|---------|---------|
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bn256.hpp |BN254 | 32 | 32 |
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bls12_381.hpp |BLS12_381, BN254 | 32 | 48 |
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bn384.hpp |BN381_1, BLS12_381, BN254| 48 | 48 |
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## C library
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* Define `MCLBN_FR_UNIT_SIZE` and `MCLBN_FP_UNIT_SIZE` and include bn.h
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* set `MCLBN_FR_UNIT_SIZE = MCLBN_FP_UNIT_SIZE` unless `MCLBN_FR_UNIT_SIZE` is defined
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library |MCLBN_FR_UNIT_SIZE|MCLBN_FP_UNIT_SIZE|
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------------------|------------------|------------------|
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sizeof | Fr | Fp |
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libmclbn256.a | 4 | 4 |
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libmclbn384_256.a | 4 | 6 |
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libmclbn384.a | 6 | 6 |
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* libmclbn*.a ; static C library
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* libmclbn*.so ; shared C library
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### 2nd argument of `mclBn_init`
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Specify `MCLBN_COMPILED_TIME_VAR` to 2nd argument of `mclBn_init`, which
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is defined as `MCLBN_FR_UNIT_SIZE * 10 + MCLBN_FP_UNIT_SIZE`.
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This parameter is used to make sure that the values are the same when the library is built and used.
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# How to initialize pairing library
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Call `mcl::bn256::initPairing` before calling any operations.
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```
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#include <mcl/bn256.hpp>
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mcl::bn::CurveParam cp = mcl::BN254; // or mcl::BN_SNARK1
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mcl::bn256::initPairing(cp);
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mcl::bn256::G1 P(...);
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mcl::bn256::G2 Q(...);
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mcl::bn256::Fp12 e;
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mcl::bn256::pairing(e, P, Q);
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```
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1. (BN254) a BN curve over the 254-bit prime p = p(z) where z = -(2^62 + 2^55 + 1).
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2. (BN_SNARK1) a BN curve over a 254-bit prime p such that n := p + 1 - t has high 2-adicity.
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3. BN381_1 with `mcl/bn384.hpp`.
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4. BN462 with `mcl/bn512.hpp`.
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See [test/bn_test.cpp](https://github.com/herumi/mcl/blob/master/test/bn_test.cpp).
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## Default constructor of Fp, Ec, etc.
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A default constructor does not initialize the instance.
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Set a valid value before reffering it.
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## Definition of groups
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The curve equation for a BN curve is:
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E/Fp: y^2 = x^3 + b .
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* the cyclic group G1 is instantiated as E(Fp)[n] where n := p + 1 - t;
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* the cyclic group G2 is instantiated as the inverse image of E'(Fp^2)[n] under a twisting isomorphism phi from E' to E; and
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* the pairing e: G1 x G2 -> Fp12 is the optimal ate pairing.
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The field Fp12 is constructed via the following tower:
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* Fp2 = Fp[u] / (u^2 + 1)
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* Fp6 = Fp2[v] / (v^3 - Xi) where Xi = u + 1
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* Fp12 = Fp6[w] / (w^2 - v)
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* GT = { x in Fp12 | x^r = 1 }
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## Arithmetic operations
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G1 and G2 is additive group and has the following operations:
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* T::add(T& z, const T& x, const T& y); // z = x + y
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* T::sub(T& z, const T& x, const T& y); // z = x - y
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* T::neg(T& y, const T& x); // y = -x
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* T::mul(T& z, const T& x, const INT& y); // z = y times scalar multiplication of x
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Remark: &z == &x or &y are allowed. INT means integer type such as Fr, int and mpz_class.
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`T::mul` uses GLV method then `G2::mul` returns wrong value if x is not in G2.
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Use `T::mulGeneric(T& z, const T& x, const INT& y)` for x in phi^-1(E'(Fp^2)) - G2.
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Fp, Fp2, Fp6 and Fp12 have the following operations:
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* T::add(T& z, const T& x, const T& y); // z = x + y
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* T::sub(T& z, const T& x, const T& y); // z = x - y
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* T::mul(T& z, const T& x, const T& y); // z = x * y
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* T::div(T& z, const T& x, const T& y); // z = x / y
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* T::neg(T& y, const T& x); // y = -x
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* T::inv(T& y, const T& x); // y = 1/x
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* T::pow(T& z, const T& x, const INT& y); // z = x^y
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* Fp12::unitaryInv(T& y, const T& x); // y = conjugate of x
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Remark: `Fp12::mul` uses GLV method then returns wrong value if x is not in GT.
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Use `Fp12::mulGeneric` for x in Fp12 - GT.
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## Map To points
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Use these functions to make a point of G1 and G2.
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* mapToG1(G1& P, const Fp& x); // assume x != 0
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* mapToG2(G2& P, const Fp2& x);
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* hashAndMapToG1(G1& P, const void *buf, size_t bufSize); // set P by the hash value of [buf, bufSize)
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* hashAndMapToG2(G2& P, const void *buf, size_t bufSize);
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These functions maps x into Gi according to [\[_Faster hashing to G2_\]].
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## String format of G1 and G2
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G1 and G2 have three elements of Fp (x, y, z) for Jacobi coordinate.
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normalize() method normalizes it to affine coordinate (x, y, 1) or (0, 0, 0).
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getStr() method gets
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* `0` ; infinity
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* `1 <x> <y>` ; not compressed format
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* `2 <x>` ; compressed format for even y
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* `3 <x>` ; compressed format for odd y
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## Generator of G1 and G2
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If you want to use the same generators of BLS12-381 with [zkcrypto](https://github.com/zkcrypto/pairing/tree/master/src/bls12_381#g2) then,
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```
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// G1 P
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P.setStr('1 3685416753713387016781088315183077757961620795782546409894578378688607592378376318836054947676345821548104185464507 1339506544944476473020471379941921221584933875938349620426543736416511423956333506472724655353366534992391756441569')
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// G2 Q
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Q.setStr('1 352701069587466618187139116011060144890029952792775240219908644239793785735715026873347600343865175952761926303160 3059144344244213709971259814753781636986470325476647558659373206291635324768958432433509563104347017837885763365758 1985150602287291935568054521177171638300868978215655730859378665066344726373823718423869104263333984641494340347905 927553665492332455747201965776037880757740193453592970025027978793976877002675564980949289727957565575433344219582')
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```
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## Serialization format of G1 and G2
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pseudo-code to serialize of p
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```
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if bit-length(p) % 8 != 0:
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size = Fp::getByteSize()
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if p is zero:
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return [0] * size
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else:
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s = x.serialize()
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# x in Fp2 is odd <=> x.a is odd
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if y is odd:
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s[byte-length(s) - 1] |= 0x80
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return s
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else:
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size = Fp::getByteSize() + 1
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if p is zero:
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return [0] * size
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else:
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s = x.serialize()
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if y is odd:
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return 2:s
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else:
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return 3:s
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```
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## Verify an element in G2
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`G2::isValid()` checks that the element is in the curve of G2 and the order of it is r for subgroup attack.
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`G2::set()`, `G2::setStr` and `operator<<` also check the order.
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If you check it out of the library, then you can stop the verification by calling `G2::verifyOrderG2(false)`.
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# How to make asm files (optional)
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The asm files generated by this way are already put in `src/asm`, then it is not necessary to do this.
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Install [LLVM](http://llvm.org/).
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```
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make MCL_USE_LLVM=1 LLVM_VER=<llvm-version> UPDATE_ASM=1
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```
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For example, specify `-3.8` for `<llvm-version>` if `opt-3.8` and `llc-3.8` are installed.
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If you want to use Fp with 1024-bit prime on x86-64, then
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```
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make MCL_USE_LLVM=1 LLVM_VER=<llvm-version> UPDATE_ASM=1 MCL_MAX_BIT_SIZE=1024
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```
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# API for Two level homomorphic encryption
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* [_Efficient Two-level Homomorphic Encryption in Prime-order Bilinear Groups and A Fast Implementation in WebAssembly_](https://dl.acm.org/citation.cfm?doid=3196494.3196552), N. Attrapadung, G. Hanaoka, S. Mitsunari, Y. Sakai,
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K. Shimizu, and T. Teruya. ASIACCS 2018
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* [she-api](https://github.com/herumi/mcl/blob/master/misc/she/she-api.md)
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* [she-api(Japanese)](https://github.com/herumi/mcl/blob/master/misc/she/she-api-ja.md)
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# Java API
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See [java.md](https://github.com/herumi/mcl/blob/master/java/java.md)
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# License
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modified new BSD License
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http://opensource.org/licenses/BSD-3-Clause
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This library contains some part of the followings software licensed by BSD-3-Clause.
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* [xbyak](https://github.com/heurmi/xbyak)
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* [cybozulib](https://github.com/heurmi/cybozulib)
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* [Lifted-ElGamal](https://github.com/aistcrypt/Lifted-ElGamal)
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# References
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* [ate-pairing](https://github.com/herumi/ate-pairing/)
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* [_Faster Explicit Formulas for Computing Pairings over Ordinary Curves_](http://dx.doi.org/10.1007/978-3-642-20465-4_5),
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D.F. Aranha, K. Karabina, P. Longa, C.H. Gebotys, J. Lopez,
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EUROCRYPTO 2011, ([preprint](http://eprint.iacr.org/2010/526))
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* [_High-Speed Software Implementation of the Optimal Ate Pairing over Barreto-Naehrig Curves_](http://dx.doi.org/10.1007/978-3-642-17455-1_2),
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Jean-Luc Beuchat, Jorge Enrique González Díaz, Shigeo Mitsunari, Eiji Okamoto, Francisco Rodríguez-Henríquez, Tadanori Teruya,
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Pairing 2010, ([preprint](http://eprint.iacr.org/2010/354))
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* [_Faster hashing to G2_](http://dx.doi.org/10.1007/978-3-642-28496-0_25),Laura Fuentes-Castañeda, Edward Knapp, Francisco Rodríguez-Henríquez,
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SAC 2011, ([preprint](https://eprint.iacr.org/2008/530))
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* [_Skew Frobenius Map and Efficient Scalar Multiplication for Pairing–Based Cryptography_](https://www.researchgate.net/publication/221282560_Skew_Frobenius_Map_and_Efficient_Scalar_Multiplication_for_Pairing-Based_Cryptography),
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Y. Sakemi, Y. Nogami, K. Okeya, Y. Morikawa, CANS 2008.
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# History
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* 2019/Feb/20 LagrangeInterpolation sets out = yVec[0] if k = 1
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* 2019/Jan/31 add mclBnFp_mapToG1, mclBnFp2_mapToG2
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* 2019/Jan/31 fix crash on x64-CPU without AVX (thanks to mortdeus)
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# Author
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光成滋生 MITSUNARI Shigeo(herumi@nifty.com)
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