C++ library for Finite Fields and Elliptic Curves
Table of contents
The directory structure is as follows:
- libff: C++ source code, containing the following modules:
- depends: dependency libraries
Elliptic curve choices
The libsnark library currently provides three options:
edwards: an instantiation based on an Edwards curve, providing 80 bits of security.
bn128: an instantiation based on a Barreto-Naehrig curve, providing 128 bits of security. The underlying curve implementation is [ate-pairing], which has incorporated our patch that changes the BN curve to one suitable for SNARK applications.
This implementation uses dynamically-generated machine code for the curve arithmetic. Some modern systems disallow execution of code on the heap, and will thus block this implementation.
For example, on Fedora 20 at its default settings, you will get the error
zmInit ERR:can't protectwhen running this code. To solve this, run
sudo setsebool -P allow_execheap 1to allow execution, or use
alt_bn128: an alternative to
bn128, somewhat slower but avoids dynamic code generation.
bn128 requires an x86-64 CPU while the other curve choices
should be architecture-independent.
The library has the following dependencies:
The library has been tested on Linux, but it is compatible with Windows and Mac OS X.
On Ubuntu 14.04 LTS:
sudo apt-get install build-essential git libboost-all-dev cmake libgmp3-dev libssl-dev libprocps3-dev pkg-config
Fetch dependencies from their GitHub repos:
git submodule init && git submodule update
To compile, starting at the project root directory, create the build directory and Makefile:
mkdir build && cd build cmake ..
If you are on macOS, change the cmake command to be
cmake .. -DOPENSSL_ROOT_DIR=$(brew --prefix openssl)
Optionally, you can specify the install location by providing the desired install path prefix:
cmake .. -DCMAKE_INSTALL_PREFIX=/install/path
Then, to compile and install the library, run this within the build directory:
make make install
This will install
/install/path/lib; so your application should be linked using
-L/install/path/lib -lff. It also installs the requisite headers into
/install/path/include; so your application should be compiled using
To execute the tests for this library, run:
To run clang-tidy on this library, specify the variable USE_CLANG_TIDY (eg.
cmake .. -D USE_CLANG_TIDY=ON).
One can specify which clang-tidy checks to run and which files to run clang-tidy on using the .clang-tidy file in the root directory of the project.
To compile the multi-exponentiation profiler in this library, run:
The resulting profiler is named
multiexp_profile and can be found in the
libff folder under the build directory.