crypto/bn256: full switchover to cloudflare's code (#16301)

* crypto/bn256: full switchover to cloudflare's code

* crypto/bn256: only use cloudflare for optimized architectures

* crypto/bn256: upstream fallback for non-optimized code

* .travis, build: drop support for Go 1.8 (need type aliases)

* crypto/bn256/cloudflare: enable curve mul lattice optimization

1 files changed, 138 insertions, 0 deletions

diff --git a/crypto/bn256/bn256_fuzz.go b/crypto/bn256/bn256_fuzz.go
new file mode 100644
index 000000000..f360b0541
--- /dev/null
+++ b/crypto/bn256/bn256_fuzz.go
@@ -0,0 +1,138 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// +build gofuzz
+
+package bn256
+
+import (
+	"bytes"
+	"math/big"
+
+	cloudflare "github.com/ethereum/go-ethereum/crypto/bn256/cloudflare"
+	google "github.com/ethereum/go-ethereum/crypto/bn256/google"
+)
+
+// FuzzAdd fuzzez bn256 addition between the Google and Cloudflare libraries.
+func FuzzAdd(data []byte) int {
+	// Ensure we have enough data in the first place
+	if len(data) != 128 {
+		return 0
+	}
+	// Ensure both libs can parse the first curve point
+	xc := new(cloudflare.G1)
+	_, errc := xc.Unmarshal(data[:64])
+
+	xg := new(google.G1)
+	_, errg := xg.Unmarshal(data[:64])
+
+	if (errc == nil) != (errg == nil) {
+		panic("parse mismatch")
+	} else if errc != nil {
+		return 0
+	}
+	// Ensure both libs can parse the second curve point
+	yc := new(cloudflare.G1)
+	_, errc = yc.Unmarshal(data[64:])
+
+	yg := new(google.G1)
+	_, errg = yg.Unmarshal(data[64:])
+
+	if (errc == nil) != (errg == nil) {
+		panic("parse mismatch")
+	} else if errc != nil {
+		return 0
+	}
+	// Add the two points and ensure they result in the same output
+	rc := new(cloudflare.G1)
+	rc.Add(xc, yc)
+
+	rg := new(google.G1)
+	rg.Add(xg, yg)
+
+	if !bytes.Equal(rc.Marshal(), rg.Marshal()) {
+		panic("add mismatch")
+	}
+	return 0
+}
+
+// FuzzMul fuzzez bn256 scalar multiplication between the Google and Cloudflare
+// libraries.
+func FuzzMul(data []byte) int {
+	// Ensure we have enough data in the first place
+	if len(data) != 96 {
+		return 0
+	}
+	// Ensure both libs can parse the curve point
+	pc := new(cloudflare.G1)
+	_, errc := pc.Unmarshal(data[:64])
+
+	pg := new(google.G1)
+	_, errg := pg.Unmarshal(data[:64])
+
+	if (errc == nil) != (errg == nil) {
+		panic("parse mismatch")
+	} else if errc != nil {
+		return 0
+	}
+	// Add the two points and ensure they result in the same output
+	rc := new(cloudflare.G1)
+	rc.ScalarMult(pc, new(big.Int).SetBytes(data[64:]))
+
+	rg := new(google.G1)
+	rg.ScalarMult(pg, new(big.Int).SetBytes(data[64:]))
+
+	if !bytes.Equal(rc.Marshal(), rg.Marshal()) {
+		panic("scalar mul mismatch")
+	}
+	return 0
+}
+
+func FuzzPair(data []byte) int {
+	// Ensure we have enough data in the first place
+	if len(data) != 192 {
+		return 0
+	}
+	// Ensure both libs can parse the curve point
+	pc := new(cloudflare.G1)
+	_, errc := pc.Unmarshal(data[:64])
+
+	pg := new(google.G1)
+	_, errg := pg.Unmarshal(data[:64])
+
+	if (errc == nil) != (errg == nil) {
+		panic("parse mismatch")
+	} else if errc != nil {
+		return 0
+	}
+	// Ensure both libs can parse the twist point
+	tc := new(cloudflare.G2)
+	_, errc = tc.Unmarshal(data[64:])
+
+	tg := new(google.G2)
+	_, errg = tg.Unmarshal(data[64:])
+
+	if (errc == nil) != (errg == nil) {
+		panic("parse mismatch")
+	} else if errc != nil {
+		return 0
+	}
+	// Pair the two points and ensure thet result in the same output
+	if cloudflare.PairingCheck([]*cloudflare.G1{pc}, []*cloudflare.G2{tc}) != google.PairingCheck([]*google.G1{pg}, []*google.G2{tg}) {
+		panic("pair mismatch")
+	}
+	return 0
+}