forked from 33cn/plugin
/
bn256.go
124 lines (106 loc) · 3.47 KB
/
bn256.go
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// Copyright Fuzamei Corp. 2018 All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import (
"errors"
"math/big"
"github.com/33cn/plugin/plugin/dapp/evm/executor/vm/common"
"github.com/33cn/plugin/plugin/dapp/evm/executor/vm/common/crypto/bn256"
"github.com/33cn/plugin/plugin/dapp/evm/executor/vm/params"
)
// newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newCurvePoint(blob []byte) (*bn256.G1, error) {
p := new(bn256.G1)
if _, err := p.Unmarshal(blob); err != nil {
return nil, err
}
return p, nil
}
// newTwistPoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newTwistPoint(blob []byte) (*bn256.G2, error) {
p := new(bn256.G2)
if _, err := p.Unmarshal(blob); err != nil {
return nil, err
}
return p, nil
}
// bn256Add implements a native elliptic curve point addition.
type bn256Add struct{}
// RequiredGas Returns the gas required to Execute the pre-compiled contract.
func (c *bn256Add) RequiredGas(input []byte) uint64 {
return params.Bn256AddGas
}
func (c *bn256Add) Run(input []byte) ([]byte, error) {
x, err := newCurvePoint(common.GetData(input, 0, 64))
if err != nil {
return nil, err
}
y, err := newCurvePoint(common.GetData(input, 64, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.Add(x, y)
return res.Marshal(), nil
}
// bn256ScalarMul implements a native elliptic curve scalar multiplication.
type bn256ScalarMul struct{}
// RequiredGas Returns the gas required to Execute the pre-compiled contract.
func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
return params.Bn256ScalarMulGas
}
func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
p, err := newCurvePoint(common.GetData(input, 0, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.ScalarMult(p, new(big.Int).SetBytes(common.GetData(input, 64, 32)))
return res.Marshal(), nil
}
var (
// true32Byte is returned if the bn256 pairing check succeeds.
true32Byte = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
// false32Byte is returned if the bn256 pairing check fails.
false32Byte = make([]byte, 32)
// errBadPairingInput is returned if the bn256 pairing input is invalid.
errBadPairingInput = errors.New("bad elliptic curve pairing size")
//errInvalidPoint = errors.New("invalid point")
)
// bn256Pairing implements a pairing pre-compile for the bn256 curve
type bn256Pairing struct{}
// RequiredGas Returns the gas required to Execute the pre-compiled contract.
func (c *bn256Pairing) RequiredGas(input []byte) uint64 {
return params.Bn256PairingBaseGas + uint64(len(input)/192)*params.Bn256PairingPerPointGas
}
func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
// Handle some corner cases cheaply
if len(input)%192 > 0 {
return nil, errBadPairingInput
}
// Convert the input into a set of coordinates
var (
cs []*bn256.G1
ts []*bn256.G2
)
for i := 0; i < len(input); i += 192 {
c, err := newCurvePoint(input[i : i+64])
if err != nil {
return nil, err
}
t, err := newTwistPoint(input[i+64 : i+192])
if err != nil {
return nil, err
}
cs = append(cs, c)
ts = append(ts, t)
}
// Execute the pairing checks and return the results
if bn256.PairingCheck(cs, ts) {
return true32Byte, nil
}
return false32Byte, nil
}