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BabySNARK

The simplest possible SNARK for NP. You know, for kids!

This is a self-contained development of SNARKs for NP. It is based on Square Span Program SNARKs by Danezis et al., which are expressive enough to encode boolean circuits.

This code accompanies a tutorial on defining and analyzing the security of a SNARK, focusing on the soundness proof. (writeup.)

Recommended usage

This is for educational purposes only. It's not efficient overall compared to state-of-the-art SNARK implementations, it doesn't come with a type system or any program analysis to rule out mistakes, and it doesn't support the zero-knowledge feature. It does, however, demonstrate some important SNARK design concepts and algorithm optimizations. It's succinct: the proof is constant size, and verifying it depends only on the size of statement, not the circuit and witness. It also achieves quasilinear overhead, through the use of FFT-based optimizations.

So, use it to study how SNARKs can be implemented, and to check your understanding of the accompanying tutorial As a project, consider extending this library to implement additional optimizations or protocol variants. This may also be useful in development for prototyping and reference implementations.

Components

Setting up

This uses Python3. There are a few python dependencies, mainly numpy and py_ecc, an implementation of pairing cryptography including bls12-381.

pip install -r requirements.txt

To run:

python babysnark.py
python babysnark_opt.py

To rebuild the jupyter notebooks:

py2nb babysnark.py
py2nb babysnark_opt.py
py2nb polynomial_evalrep.py