core/vm, crypto/bn256: switch over to cloudflare library (#16203)

* core/vm, crypto/bn256: switch over to cloudflare library

* crypto/bn256: unmarshal constraint + start pure go impl

* crypto/bn256: combo cloudflare and google lib

* travis: drop 386 test job

crypto/bn256/cloudflare/bn256_test.go

@@ -0,0 +1,118 @@
+// +build amd64,!appengine,!gccgo
+
+package bn256
+
+import (
+	"bytes"
+	"crypto/rand"
+	"testing"
+)
+
+func TestG1Marshal(t *testing.T) {
+	_, Ga, err := RandomG1(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ma := Ga.Marshal()
+
+	Gb := new(G1)
+	_, err = Gb.Unmarshal(ma)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mb := Gb.Marshal()
+
+	if !bytes.Equal(ma, mb) {
+		t.Fatal("bytes are different")
+	}
+}
+
+func TestG2Marshal(t *testing.T) {
+	_, Ga, err := RandomG2(rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ma := Ga.Marshal()
+
+	Gb := new(G2)
+	_, err = Gb.Unmarshal(ma)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mb := Gb.Marshal()
+
+	if !bytes.Equal(ma, mb) {
+		t.Fatal("bytes are different")
+	}
+}
+
+func TestBilinearity(t *testing.T) {
+	for i := 0; i < 2; i++ {
+		a, p1, _ := RandomG1(rand.Reader)
+		b, p2, _ := RandomG2(rand.Reader)
+		e1 := Pair(p1, p2)
+
+		e2 := Pair(&G1{curveGen}, &G2{twistGen})
+		e2.ScalarMult(e2, a)
+		e2.ScalarMult(e2, b)
+
+		if *e1.p != *e2.p {
+			t.Fatalf("bad pairing result: %s", e1)
+		}
+	}
+}
+
+func TestTripartiteDiffieHellman(t *testing.T) {
+	a, _ := rand.Int(rand.Reader, Order)
+	b, _ := rand.Int(rand.Reader, Order)
+	c, _ := rand.Int(rand.Reader, Order)
+
+	pa, pb, pc := new(G1), new(G1), new(G1)
+	qa, qb, qc := new(G2), new(G2), new(G2)
+
+	pa.Unmarshal(new(G1).ScalarBaseMult(a).Marshal())
+	qa.Unmarshal(new(G2).ScalarBaseMult(a).Marshal())
+	pb.Unmarshal(new(G1).ScalarBaseMult(b).Marshal())
+	qb.Unmarshal(new(G2).ScalarBaseMult(b).Marshal())
+	pc.Unmarshal(new(G1).ScalarBaseMult(c).Marshal())
+	qc.Unmarshal(new(G2).ScalarBaseMult(c).Marshal())
+
+	k1 := Pair(pb, qc)
+	k1.ScalarMult(k1, a)
+	k1Bytes := k1.Marshal()
+
+	k2 := Pair(pc, qa)
+	k2.ScalarMult(k2, b)
+	k2Bytes := k2.Marshal()
+
+	k3 := Pair(pa, qb)
+	k3.ScalarMult(k3, c)
+	k3Bytes := k3.Marshal()
+
+	if !bytes.Equal(k1Bytes, k2Bytes) || !bytes.Equal(k2Bytes, k3Bytes) {
+		t.Errorf("keys didn't agree")
+	}
+}
+
+func BenchmarkG1(b *testing.B) {
+	x, _ := rand.Int(rand.Reader, Order)
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		new(G1).ScalarBaseMult(x)
+	}
+}
+
+func BenchmarkG2(b *testing.B) {
+	x, _ := rand.Int(rand.Reader, Order)
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		new(G2).ScalarBaseMult(x)
+	}
+}
+func BenchmarkPairing(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Pair(&G1{curveGen}, &G2{twistGen})
+	}
+}