Add paralelization of polynomials in GenerateProof

- before:
BenchmarkGenerateProof-4               1        1553842743 ns/op
For a circuit of 9094 constraints takes 7.761949512s seconds to generate the proof.

- now:
BenchmarkGenerateProof-4               1        1331576862 ns/op
For a circuit of 9094 constraints takes 5.745279126s to generate the proof.

For bigger circuits (more constraints) the difference will be bigger.

Executed on a Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz, with 16GB of RAM

.gitignore

@@ -3,5 +3,6 @@ testdata/*/*.wasm
 testdata/*/*.cpp
 testdata/*/*.sym
 testdata/*/*.r1cs
+testdata/*/*.sol
 !testdata/*/input.json
 cli/*.json

prover/prover.go

@@ -4,6 +4,7 @@ import (
 	"crypto/rand"
 	"math"
 	"math/big"
+	"sync"
 
 	bn256 "github.com/ethereum/go-ethereum/crypto/bn256/cloudflare"
 	"github.com/iden3/go-circom-prover-verifier/types"
@@ -72,16 +73,39 @@ func GenerateProof(pk *types.Pk, w types.Witness) (*types.Proof, []*big.Int, err
 	proof.C = new(bn256.G1).ScalarBaseMult(big.NewInt(0))
 	proofBG1 := new(bn256.G1).ScalarBaseMult(big.NewInt(0))
 
+	var waitGroup sync.WaitGroup
+	waitGroup.Add(4)
+	go func(wg *sync.WaitGroup) {
 		for i := 0; i < pk.NVars; i++ {
 			proof.A = new(bn256.G1).Add(proof.A, new(bn256.G1).ScalarMult(pk.A[i], w[i]))
+		}
+		wg.Done()
+	}(&waitGroup)
+	go func(wg *sync.WaitGroup) {
+		for i := 0; i < pk.NVars; i++ {
 			proof.B = new(bn256.G2).Add(proof.B, new(bn256.G2).ScalarMult(pk.B2[i], w[i]))
+		}
+		wg.Done()
+	}(&waitGroup)
+	go func(wg *sync.WaitGroup) {
+		for i := 0; i < pk.NVars; i++ {
 			proofBG1 = new(bn256.G1).Add(proofBG1, new(bn256.G1).ScalarMult(pk.B1[i], w[i]))
 		}
-
+		wg.Done()
+	}(&waitGroup)
+	go func(wg *sync.WaitGroup) {
 		for i := pk.NPublic + 1; i < pk.NVars; i++ {
 			proof.C = new(bn256.G1).Add(proof.C, new(bn256.G1).ScalarMult(pk.C[i], w[i]))
 		}
+		wg.Done()
+	}(&waitGroup)
+	waitGroup.Wait()
 
+	h := calculateH(pk, w)
+
+	var waitGroup2 sync.WaitGroup
+	waitGroup2.Add(2)
+	go func(wg *sync.WaitGroup) {
 		proof.A = new(bn256.G1).Add(proof.A, pk.VkAlpha1)
 		proof.A = new(bn256.G1).Add(proof.A, new(bn256.G1).ScalarMult(pk.VkDelta1, r))
 
@@ -90,12 +114,16 @@ func GenerateProof(pk *types.Pk, w types.Witness) (*types.Proof, []*big.Int, err
 
 		proofBG1 = new(bn256.G1).Add(proofBG1, pk.VkBeta1)
 		proofBG1 = new(bn256.G1).Add(proofBG1, new(bn256.G1).ScalarMult(pk.VkDelta1, s))
-
-	h := calculateH(pk, w)
-
+		wg.Done()
+	}(&waitGroup2)
+	go func(wg *sync.WaitGroup) {
 		for i := 0; i < len(h); i++ {
 			proof.C = new(bn256.G1).Add(proof.C, new(bn256.G1).ScalarMult(pk.HExps[i], h[i]))
 		}
+		wg.Done()
+	}(&waitGroup2)
+	waitGroup2.Wait()
+
 	proof.C = new(bn256.G1).Add(proof.C, new(bn256.G1).ScalarMult(proof.A, s))
 	proof.C = new(bn256.G1).Add(proof.C, new(bn256.G1).ScalarMult(proofBG1, r))
 	rsneg := new(big.Int).Mod(new(big.Int).Neg(new(big.Int).Mul(r, s)), types.R) // fAdd & fMul

prover/prover_test.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"math/big"
 	"testing"
+	"time"
 
 	"github.com/iden3/go-circom-prover-verifier/parsers"
 	"github.com/iden3/go-circom-prover-verifier/types"
@@ -27,8 +28,10 @@ func TestSmallCircuitGenerateProof(t *testing.T) {
 
 	assert.Equal(t, types.Witness{big.NewInt(1), big.NewInt(33), big.NewInt(3), big.NewInt(11)}, w)
 
+	beforeT := time.Now()
 	proof, pubSignals, err := GenerateProof(pk, w)
 	assert.Nil(t, err)
+	fmt.Println("proof generation time elapsed:", time.Since(beforeT))
 
 	proofStr, err := parsers.ProofToJson(proof)
 	assert.Nil(t, err)
@@ -64,8 +67,10 @@ func TestBigCircuitGenerateProof(t *testing.T) {
 	w, err := parsers.ParseWitness(witnessJson)
 	require.Nil(t, err)
 
+	beforeT := time.Now()
 	proof, pubSignals, err := GenerateProof(pk, w)
 	assert.Nil(t, err)
+	fmt.Println("proof generation time elapsed:", time.Since(beforeT))
 
 	proofStr, err := parsers.ProofToJson(proof)
 	assert.Nil(t, err)
@@ -99,7 +104,7 @@ func TestIdStateCircuitGenerateProof(t *testing.T) {
 	// trustedsetup files (generated in
 	// https://github.com/iden3/go-zksnark-full-flow-example)
 	if false {
-		fmt.Println("TestIdStateCircuitGenerateProof activated")
+		fmt.Println("\nTestIdStateCircuitGenerateProof activated")
 		provingKeyJson, err := ioutil.ReadFile("../testdata/idstate-circuit/proving_key.json")
 		require.Nil(t, err)
 		pk, err := parsers.ParsePk(provingKeyJson)
@@ -110,8 +115,10 @@ func TestIdStateCircuitGenerateProof(t *testing.T) {
 		w, err := parsers.ParseWitness(witnessJson)
 		require.Nil(t, err)
 
+		beforeT := time.Now()
 		proof, pubSignals, err := GenerateProof(pk, w)
 		assert.Nil(t, err)
+		fmt.Println("proof generation time elapsed:", time.Since(beforeT))
 
 		proofStr, err := parsers.ProofToJson(proof)
 		assert.Nil(t, err)