Python3 bindings for a minimal subset of libsnark. Currently supports Pinocchio and Groth proofs on the alt_bn128 curve, compatible with snarkjs, websnark, Solidity pairings, etc.

See minimal examlple and use in PySNARK.

Install from pip with

pip install python-libsnark

Binary versions available at PyPi for Linux/Mac OS/Windows .

Functionality

The following classes of libsnark are currently wrapped:

General:

typedef libff::Fr<libff::alt_bn128_pp> Ft;
%template(Variable) libsnark::variable<Ft>;
%template(PbVariable) libsnark::pb_variable<Ft>;
%template(LinearCombination) libsnark::linear_combination<Ft>;
%template(R1csConstraint) libsnark::r1cs_constraint<Ft>;
%template(R1csConstraintSystem) libsnark::r1cs_constraint_system<Ft>;
%template(R1csPrimaryInput) libsnark::r1cs_primary_input<Ft>;
%template(R1csAuxiliaryInput) libsnark::r1cs_auxiliary_input<Ft>;
%template(Protoboard) libsnark::protoboard<Ft>;

Pinocchio zk-SNARK (aka 8-point proofs):

%template(ZKProof) libsnark::r1cs_ppzksnark_proof<libff::alt_bn128_pp>;
%template(ZKKeypair) libsnark::r1cs_ppzksnark_keypair<libff::alt_bn128_pp>;
%template(zk_generator) libsnark::r1cs_ppzksnark_generator<libff::alt_bn128_pp>;
%template(zk_prover) libsnark::r1cs_ppzksnark_prover<libff::alt_bn128_pp>;
%template(zk_verifier_weak_IC) libsnark::r1cs_ppzksnark_verifier_weak_IC<libff::alt_bn128_pp>;
%template(zk_verifier_strong_IC) libsnark::r1cs_ppzksnark_verifier_strong_IC<libff::alt_bn128_pp>;

Groth 3-point proof:

%template(ZKGGProof) libsnark::r1cs_gg_ppzksnark_proof<libff::alt_bn128_pp>;
%template(ZKGGKeypair) libsnark::r1cs_gg_ppzksnark_keypair<libff::alt_bn128_pp>;
%template(zkgg_generator) libsnark::r1cs_gg_ppzksnark_generator<libff::alt_bn128_pp>;
%template(zkgg_prover) libsnark::r1cs_gg_ppzksnark_prover<libff::alt_bn128_pp>;
%template(zkgg_verifier_weak_IC) libsnark::r1cs_gg_ppzksnark_verifier_weak_IC<libff::alt_bn128_pp>;
%template(zkgg_verifier_strong_IC) libsnark::r1cs_gg_ppzksnark_verifier_strong_IC<libff::alt_bn128_pp>;

Known issues

• Evaluation keys are not compatible between 32-bit and 64-bit versions of the module because of the use of Montgomery representations. Verification keys should be OK. This may be fixed in future versions.

Building from source

When building from source it is assumed tht this libsnark branch is built with cmake -DCURVE=ALT_BN128 -DUSE_PT_COMPRESSION=OFF -DWITH_PROCPS=OFF and installed. If libsnark is built with different flags, setup.py's extra_compile_flags should be adapted.

Under Linux, the following sequence of commands can be used to install libsnark:

git clone --recursive https://github.com/meilof/libsnark
cd libsnark/
mkdir build
cd build/
cmake .. -DCURVE=ALT_BN128 -DUSE_PT_COMPRESSION=OFF -DWITH_PROCPS=OFF -DBINARY_OUTPUT=OFF
make
sudo make install

For Mac OS, flags like -DCMAKE_PREFIX_PATH=/usr/local/Cellar/openssl/1.0.2t -DCMAKE_SHARED_LINKER_FLAGS=-L/usr/local/Cellar/openssl/1.0.2t/lib can be added.

The wrapper is created using SWIG. To update the wrapper, use swig -python -c++ -o alt_bn128_wrap.cpp libsnark.i.

Mac OS X

To compile libsnark, use:

sudo cmake -DCMAKE_PREFIX_PATH=/usr/local/opt/openssl\@1.1/ -DCMAKE_SHARED_LINKER_FLAGS=-L/usr/local/opt/openssl\@1.1/lib -DWITH_PROCPS=OFF -DWITH_SUPERCOP=OFF -DOPT_FLAGS=-std=c++11 -DCURVE=ALT_BN128 ..

To build manylinux packages

docker run -it -v $(pwd):/io quay.io/pypa/manylinux2010_x86_64

inside the docker:

yum install cmake3 openssl-devel boost-devel gmp-devel
build and install libgmp with ./configure --enable-cxx; make install
cmake3 .. -DCURVE=ALT_BN128 -DUSE_PT_COMPRESSION=OFF -DWITH_PROCPS=OFF -DBINARY_OUTPUT=OFF
make install
cd python-libsnark
/opt/python/cp34-cp34m/bin/pip wheel . -w wheelhouse/
auditwheel repair /io/python-libsnark/wheelhouse/python_libsnark-0.3.2-cp38-cp38-linux_x86_64.whl 
etc
twine upload *