go-snark/README.md
README.mdRaw
1# go-snark [](https://goreportcard.com/report/github.com/arnaucube/go-snark)
2
3zkSNARK library implementation in Go
4
5
6- `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
7- `Pinocchio: Nearly practical verifiable computation`, Bryan Parno, Craig Gentry, Jon Howell, Mariana Raykova https://eprint.iacr.org/2013/279.pdf
8
9## Caution, Warning
10Implementation of the zkSNARK [Pinocchio protocol](https://eprint.iacr.org/2013/279.pdf) from scratch in Go to understand the concepts. Do not use in production.
11
12Not finished, implementing this in my free time to understand it better, so I don't have much time.
13
14Current implementation status:
15- [x] Finite Fields (1, 2, 6, 12) operations
16- [x] G1 and G2 curve operations
17- [x] BN128 Pairing
18- [x] circuit code compiler
19 - [ ] code to flat code (improve circuit compiler)
20 - [x] flat code compiler
21- [x] circuit to R1CS
22- [x] polynomial operations
23- [x] R1CS to QAP
24- [x] generate trusted setup
25- [x] generate proofs
26- [x] verify proofs with BN128 pairing
27- [ ] move witness calculation outside the setup phase
28- [ ] Groth16
29- [ ] multiple optimizations
30
31
32## Usage
33- [](https://godoc.org/github.com/arnaucube/go-snark) zkSnark
34- [](https://godoc.org/github.com/arnaucube/go-snark/bn128) bn128 (more details: https://github.com/arnaucube/go-snark/tree/master/bn128)
35- [](https://godoc.org/github.com/arnaucube/go-snark/fields) Finite Fields operations
36- [](https://godoc.org/github.com/arnaucube/go-snark/r1csqap) R1CS to QAP (more details: https://github.com/arnaucube/go-snark/tree/master/r1csqap)
37- [](https://godoc.org/github.com/arnaucube/go-snark/circuitcompiler) Circuit Compiler
38
39### Library usage
40Warning: not finished.
41
42Example:
43```go
44// compile circuit and get the R1CS
45flatCode := `
46func test(private s0, public s1):
47 s2 = s0 * s0
48 s3 = s2 * s0
49 s4 = s3 + s0
50 s5 = s4 + 5
51 equals(s1, s5)
52 out = 1 * 1
53`
54
55// parse the code
56parser := circuitcompiler.NewParser(strings.NewReader(flatCode))
57circuit, err := parser.Parse()
58assert.Nil(t, err)
59fmt.Println(circuit)
60
61
62b3 := big.NewInt(int64(3))
63privateInputs := []*big.Int{b3}
64b35 := big.NewInt(int64(35))
65publicSignals := []*big.Int{b35}
66
67// witness
68w, err := circuit.CalculateWitness(privateInputs, publicSignals)
69assert.Nil(t, err)
70fmt.Println("witness", w)
71
72// now we have the witness:
73// w = [1 35 3 9 27 30 35 1]
74
75// flat code to R1CS
76fmt.Println("generating R1CS from flat code")
77a, b, c := circuit.GenerateR1CS()
78
79/*
80now we have the R1CS from the circuit:
81a: [[0 0 1 0 0 0 0 0] [0 0 0 1 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]]
82b: [[0 0 1 0 0 0 0 0] [0 0 1 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] [1 0 0 0 0 0 0 0]]
83c: [[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]]
84*/
85
86
87alphas, betas, gammas, _ := snark.Utils.PF.R1CSToQAP(a, b, c)
88
89
90ax, bx, cx, px := Utils.PF.CombinePolynomials(w, alphas, betas, gammas)
91
92// calculate trusted setup
93setup, err := GenerateTrustedSetup(len(w), *circuit, alphas, betas, gammas)
94
95hx := Utils.PF.DivisorPolynomial(px, setup.Pk.Z)
96
97proof, err := GenerateProofs(*circuit, setup, w, px)
98
99b35Verif := big.NewInt(int64(35))
100publicSignalsVerif := []*big.Int{b35Verif}
101assert.True(t, VerifyProof(*circuit, setup, proof, publicSignalsVerif, true))
102```
103
104### CLI usage
105
106#### Compile circuit
107Having a circuit file `test.circuit`:
108```
109func test(private s0, public s1):
110 s2 = s0 * s0
111 s3 = s2 * s0
112 s4 = s3 + s0
113 s5 = s4 + 5
114 equals(s1, s5)
115 out = 1 * 1
116```
117And a private inputs file `privateInputs.json`
118```
119[
120 3
121]
122```
123And a public inputs file `publicInputs.json`
124```
125[
126 35
127]
128```
129
130In the command line, execute:
131```
132> go-snark-cli compile test.circuit
133```
134
135This will output the `compiledcircuit.json` file.
136
137#### Trusted Setup
138Having the `compiledcircuit.json`, now we can generate the `TrustedSetup`:
139```
140> go-snark-cli trustedsetup
141```
142This 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`.
143
144
145#### Generate Proofs
146Assumming that we have the `compiledcircuit.json`, `trustedsetup.json`, `privateInputs.json` and the `publicInputs.json` we can now generate the `Proofs` with the following command:
147```
148> go-snark-cli genproofs
149```
150
151This will store the file `proofs.json`, that contains all the SNARK proofs.
152
153#### Verify Proofs
154Having 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.
155```
156> go-snark-cli verify
157```
158This will return a `true` if the proofs are verified, or a `false` if the proofs are not verified.
159
160
161
162## Test
163```
164go test ./... -v
165```
166
167---
168
169
170Thanks 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.