# go-snark [![Go Report Card](https://goreportcard.com/badge/github.com/arnaucube/go-snark)](https://goreportcard.com/report/github.com/arnaucube/go-snark) [![Build Status](https://travis-ci.org/arnaucube/go-snark.svg?branch=master)](https://travis-ci.org/arnaucube/go-snark) [![Gitter](https://badges.gitter.im/go-snark/community.svg)](https://gitter.im/go-snark/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge) zkSNARK library implementation in Go - `Succinct Non-Interactive Zero Knowledge for a von Neumann Architecture`, Eli Ben-Sasson, Alessandro Chiesa, Eran Tromer, Madars Virza https://eprint.iacr.org/2013/879.pdf - `Pinocchio: Nearly practical verifiable computation`, Bryan Parno, Craig Gentry, Jon Howell, Mariana Raykova https://eprint.iacr.org/2013/279.pdf - `On the Size of Pairing-based Non-interactive Arguments`, Jens Groth https://eprint.iacr.org/2016/260.pdf ## Caution & Warning Implementation of the zkSNARK [Pinocchio protocol](https://eprint.iacr.org/2013/279.pdf) and [Groth16 protocol](https://eprint.iacr.org/2016/260.pdf) from scratch in Go to understand the concepts. Do not use in production. Not finished, implementing this in my free time to understand it better, so I don't have much time. Currently allows to do the complete path with [Pinocchio protocol](https://eprint.iacr.org/2013/279.pdf) and [Groth16 protocol](https://eprint.iacr.org/2016/260.pdf) : 0. write circuit 1. compile circuit 2. generate trusted setup 3. calculate witness 4. generate proofs 5. verify proofs Minimal complete flow implementation: - [x] Finite Fields (1, 2, 6, 12) operations - [x] G1 and G2 curve operations - [x] BN128 Pairing - [x] circuit flat code compiler - [x] circuit to R1CS - [x] polynomial operations - [x] R1CS to QAP - [x] generate trusted setup - [x] generate proofs - [x] verify proofs with BN128 pairing Improvements from the minimal implementation: - [x] allow to call functions in circuits language - [x] allow `import` in circuits language - [ ] allow `for` in circuits language - [ ] move witness values calculation outside the setup phase - [x] Groth16 - [ ] multiple optimizations ## Usage - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark?status.svg)](https://godoc.org/github.com/arnaucube/go-snark) zkSnark - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark/groth16?status.svg)](https://godoc.org/github.com/arnaucube/go-snark/groth16) zkSnark Groth16 - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark/bn128?status.svg)](https://godoc.org/github.com/arnaucube/go-snark/bn128) bn128 (more details: https://github.com/arnaucube/go-snark/tree/master/bn128) - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark/fields?status.svg)](https://godoc.org/github.com/arnaucube/go-snark/fields) Finite Fields operations - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark/r1csqap?status.svg)](https://godoc.org/github.com/arnaucube/go-snark/r1csqap) R1CS to QAP (more details: https://github.com/arnaucube/go-snark/tree/master/r1csqap) - [![GoDoc](https://godoc.org/github.com/arnaucube/go-snark/circuitcompiler?status.svg)](https://godoc.org/github.com/arnaucube/go-snark/circuitcompiler) Circuit Compiler ### CLI usage *The cli still needs some improvements, such as seting input files, etc.* In this example we will follow the equation example from [Vitalik](https://medium.com/@VitalikButerin/quadratic-arithmetic-programs-from-zero-to-hero-f6d558cea649)'s article: `y = x^3 + x + 5`, where `y==35` and `x==3`. So we want to prove that we know a secret `x` such as the result of the equation is `35`. #### Compile circuit Having a circuit file `test.circuit`: ``` func exp3(private a): b = a * a c = a * b return c func main(private s0, public s1): s3 = exp3(s0) s4 = s3 + s0 s5 = s4 + 5 equals(s1, s5) out = 1 * 1 ``` And a private inputs file `privateInputs.json` ``` [ 3 ] ``` And a public inputs file `publicInputs.json` ``` [ 35 ] ``` In the command line, execute: ``` > ./go-snark-cli compile test.circuit ``` This will output the `compiledcircuit.json` file. #### Trusted Setup Having the `compiledcircuit.json`, now we can generate the `TrustedSetup`: ``` > ./go-snark-cli trustedsetup ``` This will create the file `trustedsetup.json` with the TrustedSetup data, and also a `toxic.json` file, with the parameters to delete from the `Trusted Setup`. #### Generate Proofs Assumming that we have the `compiledcircuit.json`, `trustedsetup.json`, `privateInputs.json` and the `publicInputs.json` we can now generate the `Proofs` with the following command: ``` > ./go-snark-cli genproofs ``` This will store the file `proofs.json`, that contains all the SNARK proofs. #### Verify Proofs Having the `proofs.json`, `compiledcircuit.json`, `trustedsetup.json` `publicInputs.json` files, we can now verify the `Pairings` of the proofs, in order to verify the proofs. ``` > ./go-snark-cli verify ``` This will return a `true` if the proofs are verified, or a `false` if the proofs are not verified. ### Cli using Groth16 All this process can be done using [Groth16 protocol](https://eprint.iacr.org/2016/260.pdf) protocol: ``` > ./go-snark-cli compile test.circuit > ./go-snark-cli groth16 trustedsetup > ./go-snark-cli groth16 genproofs > ./go-snark-cli verify ``` ### Library usage Example: ```go // compile circuit and get the R1CS flatCode := ` func exp3(private a): b = a * a c = a * b return c func main(private s0, public s1): s3 = exp3(s0) s4 = s3 + s0 s5 = s4 + 5 equals(s1, s5) out = 1 * 1 ` // parse the code parser := circuitcompiler.NewParser(strings.NewReader(flatCode)) circuit, err := parser.Parse() assert.Nil(t, err) fmt.Println(circuit) b3 := big.NewInt(int64(3)) privateInputs := []*big.Int{b3} b35 := big.NewInt(int64(35)) publicSignals := []*big.Int{b35} // witness w, err := circuit.CalculateWitness(privateInputs, publicSignals) assert.Nil(t, err) fmt.Println("witness", w) // now we have the witness: // w = [1 35 3 9 27 30 35 1] // flat code to R1CS fmt.Println("generating R1CS from flat code") a, b, c := circuit.GenerateR1CS() /* now we have the R1CS from the circuit: a: [[0 0 1 0 0 0 0 0] [0 0 1 0 0 0 0 0] [0 0 1 0 1 0 0 0] [5 0 0 0 0 1 0 0] [0 0 0 0 0 0 1 0] [0 1 0 0 0 0 0 0] [1 0 0 0 0 0 0 0]] b: [[0 0 1 0 0 0 0 0] [0 0 0 1 0 0 0 0] [1 0 0 0 0 0 0 0] [1 0 0 0 0 0 0 0] [1 0 0 0 0 0 0 0] [1 0 0 0 0 0 0 0] [1 0 0 0 0 0 0 0]] c: [[0 0 0 1 0 0 0 0] [0 0 0 0 1 0 0 0] [0 0 0 0 0 1 0 0] [0 0 0 0 0 0 1 0] [0 1 0 0 0 0 0 0] [0 0 0 0 0 0 1 0] [0 0 0 0 0 0 0 1]] */ alphas, betas, gammas, _ := snark.Utils.PF.R1CSToQAP(a, b, c) ax, bx, cx, px := Utils.PF.CombinePolynomials(w, alphas, betas, gammas) // calculate trusted setup setup, err := GenerateTrustedSetup(len(w), *circuit, alphas, betas, gammas) hx := Utils.PF.DivisorPolynomial(px, setup.Pk.Z) proof, err := GenerateProofs(*circuit, setup, w, px) b35Verif := big.NewInt(int64(35)) publicSignalsVerif := []*big.Int{b35Verif} assert.True(t, VerifyProof(*circuit, setup, proof, publicSignalsVerif, true)) ``` ## Versions History of versions & tags of this project: - v0.0.1: zkSnark complete flow working with Pinocchio protocol - v0.0.2: circuit language improved (allow function calls and file imports) - v0.0.3: Groth16 zkSnark protocol added ## Test ``` go test ./... -v ``` ## vim/nvim circuit syntax highlighter For more details and installation instructions see https://github.com/arnaucube/go-snark/tree/master/vim-syntax --- Thanks to [@jbaylina](https://github.com/jbaylina), [@bellesmarta](https://github.com/bellesmarta), [@adriamb](https://github.com/adriamb) for their explanations that helped to understand this a little bit. Also thanks to [@vbuterin](https://github.com/vbuterin) for all the published articles explaining the zkSNARKs.