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 (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 - [ ] fix 4th pairing proofs generation & verification: ê(Vkx+piA, piB) == ê(piH, Vkz) * ê(piC, g2)
28- [ ] WASM implementation to run on browsers
29
30
31## Usage
32- [](https://godoc.org/github.com/arnaucube/go-snark) zkSnark
33- [](https://godoc.org/github.com/arnaucube/go-snark/bn128) bn128 (more details: https://github.com/arnaucube/go-snark/tree/master/bn128)
34- [](https://godoc.org/github.com/arnaucube/go-snark/fields) Finite Fields operations
35- [](https://godoc.org/github.com/arnaucube/go-snark/r1csqap) R1CS to QAP (more details: https://github.com/arnaucube/go-snark/tree/master/r1csqap)
36- [](https://godoc.org/github.com/arnaucube/go-snark/circuitcompiler) Circuit Compiler
37
38### Library usage
39Warning: not finished.
40
41Example:
42```go
43// compile circuit and get the R1CS
44flatCode := `
45func test(x):
46 aux = x*x
47 y = aux*x
48 z = x + y
49 out = z + 5
50`
51
52// parse the code
53parser := circuitcompiler.NewParser(strings.NewReader(flatCode))
54circuit, err := parser.Parse()
55assert.Nil(t, err)
56fmt.Println(circuit)
57
58// witness
59b3 := big.NewInt(int64(3))
60inputs := []*big.Int{b3}
61w := circuit.CalculateWitness(inputs)
62fmt.Println("\nwitness", w)
63/*
64now we have the witness:
65w = [1 3 35 9 27 30]
66*/
67
68// flat code to R1CS
69fmt.Println("generating R1CS from flat code")
70a, b, c := circuit.GenerateR1CS()
71
72/*
73now we have the R1CS from the circuit:
74a == [[0 1 0 0 0 0] [0 0 0 1 0 0] [0 1 0 0 1 0] [5 0 0 0 0 1]]
75b == [[0 1 0 0 0 0] [0 1 0 0 0 0] [1 0 0 0 0 0] [1 0 0 0 0 0]]
76c == [[0 0 0 1 0 0] [0 0 0 0 1 0] [0 0 0 0 0 1] [0 0 1 0 0 0]]
77*/
78
79
80alphas, betas, gammas, zx := snark.Utils.PF.R1CSToQAP(a, b, c)
81
82
83ax, bx, cx, px := snark.Utils.PF.CombinePolynomials(w, alphas, betas, gammas)
84
85hx := snark.Utils.PF.DivisorPolinomial(px, zx)
86
87// hx==px/zx so px==hx*zx
88assert.Equal(t, px, snark.Utils.PF.Mul(hx, zx))
89
90// p(x) = a(x) * b(x) - c(x) == h(x) * z(x)
91abc := snark.Utils.PF.Sub(pf.Mul(ax, bx), cx)
92assert.Equal(t, abc, px)
93hz := snark.Utils.PF.Mul(hx, zx)
94assert.Equal(t, abc, hz)
95
96div, rem := snark.Utils.PF.Div(px, zx)
97assert.Equal(t, hx, div)
98assert.Equal(t, rem, r1csqap.ArrayOfBigZeros(4))
99
100// calculate trusted setup
101setup, err := snark.GenerateTrustedSetup(len(w), circuit, alphas, betas, gammas, zx)
102assert.Nil(t, err)
103fmt.Println("t", setup.Toxic.T)
104
105// piA = g1 * A(t), piB = g2 * B(t), piC = g1 * C(t), piH = g1 * H(t)
106proof, err := snark.GenerateProofs(circuit, setup, hx, w)
107assert.Nil(t, err)
108
109assert.True(t, snark.VerifyProof(circuit, setup, proof))
110```
111
112### CLI usage
113
114#### Compile circuit
115Having a circuit file `test.circuit`:
116```
117func test(x):
118 aux = x*x
119 y = aux*x
120 z = x + y
121 out = z + 5
122```
123And a inputs file `inputs.json`
124```
125[
126 3
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` and the `trustedsetup.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` 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.