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
10Implementation 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
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
28
29## Usage
30- [](https://godoc.org/github.com/arnaucube/go-snark) zkSnark
31- [](https://godoc.org/github.com/arnaucube/go-snark/bn128) bn128 (more details: https://github.com/arnaucube/go-snark/tree/master/bn128)
32- [](https://godoc.org/github.com/arnaucube/go-snark/fields) Finite Fields operations
33- [](https://godoc.org/github.com/arnaucube/go-snark/r1csqap) R1CS to QAP (more details: https://github.com/arnaucube/go-snark/tree/master/r1csqap)
34- [](https://godoc.org/github.com/arnaucube/go-snark/circuitcompiler) Circuit Compiler
35
36### Library usage
37Example:
38```go
39// compile circuit and get the R1CS
40flatCode := `
41func test(x):
42 aux = x*x
43 y = aux*x
44 z = x + y
45 out = z + 5
46`
47
48// parse the code
49parser := circuitcompiler.NewParser(strings.NewReader(flatCode))
50circuit, err := parser.Parse()
51assert.Nil(t, err)
52fmt.Println(circuit)
53
54// witness
55b3 := big.NewInt(int64(3))
56inputs := []*big.Int{b3}
57w := circuit.CalculateWitness(inputs)
58fmt.Println("\nwitness", w)
59/*
60now we have the witness:
61w = [1 3 35 9 27 30]
62*/
63
64// flat code to R1CS
65fmt.Println("generating R1CS from flat code")
66a, b, c := circuit.GenerateR1CS()
67
68/*
69now we have the R1CS from the circuit:
70a == [[0 1 0 0 0 0] [0 0 0 1 0 0] [0 1 0 0 1 0] [5 0 0 0 0 1]]
71b == [[0 1 0 0 0 0] [0 1 0 0 0 0] [1 0 0 0 0 0] [1 0 0 0 0 0]]
72c == [[0 0 0 1 0 0] [0 0 0 0 1 0] [0 0 0 0 0 1] [0 0 1 0 0 0]]
73*/
74
75
76alphas, betas, gammas, zx := snark.Utils.PF.R1CSToQAP(a, b, c)
77
78
79ax, bx, cx, px := snark.Utils.PF.CombinePolynomials(w, alphas, betas, gammas)
80
81hx := snark.Utils.PF.DivisorPolinomial(px, zx)
82
83// hx==px/zx so px==hx*zx
84assert.Equal(t, px, snark.Utils.PF.Mul(hx, zx))
85
86// p(x) = a(x) * b(x) - c(x) == h(x) * z(x)
87abc := snark.Utils.PF.Sub(pf.Mul(ax, bx), cx)
88assert.Equal(t, abc, px)
89hz := snark.Utils.PF.Mul(hx, zx)
90assert.Equal(t, abc, hz)
91
92div, rem := snark.Utils.PF.Div(px, zx)
93assert.Equal(t, hx, div)
94assert.Equal(t, rem, r1csqap.ArrayOfBigZeros(4))
95
96// calculate trusted setup
97setup, err := snark.GenerateTrustedSetup(len(w), circuit, alphas, betas, gammas, zx)
98assert.Nil(t, err)
99fmt.Println("t", setup.Toxic.T)
100
101// piA = g1 * A(t), piB = g2 * B(t), piC = g1 * C(t), piH = g1 * H(t)
102proof, err := snark.GenerateProofs(circuit, setup, hx, w)
103assert.Nil(t, err)
104
105assert.True(t, snark.VerifyProof(circuit, setup, proof))
106```
107
108### CLI usage
109
110#### Compile circuit
111Having a circuit file `test.circuit`:
112```
113func test(x):
114 aux = x*x
115 y = aux*x
116 z = x + y
117 out = z + 5
118```
119And a inputs file `inputs.json`
120```
121[
122 3
123]
124```
125
126In the command line, execute:
127```
128> go-snark-cli compile test.circuit
129```
130
131This will output the `compiledcircuit.json` file.
132
133#### Trusted Setup
134Having the `compiledcircuit.json`, now we can generate the `TrustedSetup`:
135```
136> go-snark-cli trustedsetup
137```
138This 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`.
139
140
141#### Generate Proofs
142Assumming that we have the `compiledcircuit.json` and the `trustedsetup.json`, we can now generate the `Proofs` with the following command:
143```
144> go-snark-cli genproofs
145```
146
147This will store the file `proofs.json`, that contains all the SNARK proofs.
148
149#### Verify Proofs
150Having the `proofs.json`, `compiledcircuit.json`, `trustedsetup.json` files, we can now verify the `Pairings` of the proofs, in order to verify the proofs.
151```
152> go-snark-cli verify
153```
154This will return a `true` if the proofs are verified, or a `false` if the proofs are not verified.
155
156
157
158## Test
159```
160go test ./... -v
161```
162
163---
164
165
166Thanks 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.