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// Copyright 2014 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/>.
package vm
import (
"crypto/sha256"
"encoding/binary"
"errors"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/blake2b"
"github.com/ethereum/go-ethereum/crypto/bls12381"
"github.com/ethereum/go-ethereum/crypto/bn256"
"github.com/ethereum/go-ethereum/params"
//lint:ignore SA1019 Needed for precompile
"golang.org/x/crypto/ripemd160"
)
// PrecompiledContract is the basic interface for native Go contracts. The implementation
// requires a deterministic gas count based on the input size of the Run method of the
// contract.
type PrecompiledContract interface {
RequiredGas(input []byte) uint64 // RequiredPrice calculates the contract gas use
Run(input []byte) ([]byte, error) // Run runs the precompiled contract
}
// PrecompiledContractsHomestead contains the default set of pre-compiled Ethereum
// contracts used in the Frontier and Homestead releases.
var PrecompiledContractsHomestead = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
}
// PrecompiledContractsByzantium contains the default set of pre-compiled Ethereum
// contracts used in the Byzantium release.
var PrecompiledContractsByzantium = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
common.BytesToAddress([]byte{5}): &bigModExp{},
common.BytesToAddress([]byte{6}): &bn256AddByzantium{},
common.BytesToAddress([]byte{7}): &bn256ScalarMulByzantium{},
common.BytesToAddress([]byte{8}): &bn256PairingByzantium{},
}
// PrecompiledContractsIstanbul contains the default set of pre-compiled Ethereum
// contracts used in the Istanbul release.
var PrecompiledContractsIstanbul = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
common.BytesToAddress([]byte{5}): &bigModExp{},
common.BytesToAddress([]byte{6}): &bn256AddIstanbul{},
common.BytesToAddress([]byte{7}): &bn256ScalarMulIstanbul{},
common.BytesToAddress([]byte{8}): &bn256PairingIstanbul{},
common.BytesToAddress([]byte{9}): &blake2F{},
}
// PrecompiledContractsYoloV1 contains the default set of pre-compiled Ethereum
// contracts used in the Yolo v1 test release.
var PrecompiledContractsYoloV1 = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
common.BytesToAddress([]byte{5}): &bigModExp{},
common.BytesToAddress([]byte{6}): &bn256AddIstanbul{},
common.BytesToAddress([]byte{7}): &bn256ScalarMulIstanbul{},
common.BytesToAddress([]byte{8}): &bn256PairingIstanbul{},
common.BytesToAddress([]byte{9}): &blake2F{},
common.BytesToAddress([]byte{10}): &bls12381G1Add{},
common.BytesToAddress([]byte{11}): &bls12381G1Mul{},
common.BytesToAddress([]byte{12}): &bls12381G1MultiExp{},
common.BytesToAddress([]byte{13}): &bls12381G2Add{},
common.BytesToAddress([]byte{14}): &bls12381G2Mul{},
common.BytesToAddress([]byte{15}): &bls12381G2MultiExp{},
common.BytesToAddress([]byte{16}): &bls12381Pairing{},
common.BytesToAddress([]byte{17}): &bls12381MapG1{},
common.BytesToAddress([]byte{18}): &bls12381MapG2{},
}
// RunPrecompiledContract runs and evaluates the output of a precompiled contract.
// It returns
// - the returned bytes,
// - the _remaining_ gas,
// - any error that occurred
func RunPrecompiledContract(p PrecompiledContract, input []byte, suppliedGas uint64) (ret []byte, remainingGas uint64, err error) {
gasCost := p.RequiredGas(input)
if suppliedGas < gasCost {
return nil, 0, ErrOutOfGas
}
suppliedGas -= gasCost
output, err := p.Run(input)
return output, suppliedGas, err
}
// ECRECOVER implemented as a native contract.
type ecrecover struct{}
func (c *ecrecover) RequiredGas(input []byte) uint64 {
return params.EcrecoverGas
}
func (c *ecrecover) Run(input []byte) ([]byte, error) {
const ecRecoverInputLength = 128
input = common.RightPadBytes(input, ecRecoverInputLength)
// "input" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
r := new(big.Int).SetBytes(input[64:96])
s := new(big.Int).SetBytes(input[96:128])
v := input[63] - 27
// tighter sig s values input homestead only apply to tx sigs
if !allZero(input[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
return nil, nil
}
// We must make sure not to modify the 'input', so placing the 'v' along with
// the signature needs to be done on a new allocation
sig := make([]byte, 65)
copy(sig, input[64:128])
sig[64] = v
// v needs to be at the end for libsecp256k1
pubKey, err := crypto.Ecrecover(input[:32], sig)
// make sure the public key is a valid one
if err != nil {
return nil, nil
}
// the first byte of pubkey is bitcoin heritage
return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
}
// SHA256 implemented as a native contract.
type sha256hash struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *sha256hash) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.Sha256PerWordGas + params.Sha256BaseGas
}
func (c *sha256hash) Run(input []byte) ([]byte, error) {
h := sha256.Sum256(input)
return h[:], nil
}
// RIPEMD160 implemented as a native contract.
type ripemd160hash struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.Ripemd160PerWordGas + params.Ripemd160BaseGas
}
func (c *ripemd160hash) Run(input []byte) ([]byte, error) {
ripemd := ripemd160.New()
ripemd.Write(input)
return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
}
// data copy implemented as a native contract.
type dataCopy struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *dataCopy) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.IdentityPerWordGas + params.IdentityBaseGas
}
func (c *dataCopy) Run(in []byte) ([]byte, error) {
return in, nil
}
// bigModExp implements a native big integer exponential modular operation.
type bigModExp struct{}
var (
big0 = big.NewInt(0)
big1 = big.NewInt(1)
big4 = big.NewInt(4)
big8 = big.NewInt(8)
big16 = big.NewInt(16)
big32 = big.NewInt(32)
big64 = big.NewInt(64)
big96 = big.NewInt(96)
big480 = big.NewInt(480)
big1024 = big.NewInt(1024)
big3072 = big.NewInt(3072)
big199680 = big.NewInt(199680)
)
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bigModExp) RequiredGas(input []byte) uint64 {
var (
baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
expLen = new(big.Int).SetBytes(getData(input, 32, 32))
modLen = new(big.Int).SetBytes(getData(input, 64, 32))
)
if len(input) > 96 {
input = input[96:]
} else {
input = input[:0]
}
// Retrieve the head 32 bytes of exp for the adjusted exponent length
var expHead *big.Int
if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
expHead = new(big.Int)
} else {
if expLen.Cmp(big32) > 0 {
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
} else {
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
}
}
// Calculate the adjusted exponent length
var msb int
if bitlen := expHead.BitLen(); bitlen > 0 {
msb = bitlen - 1
}
adjExpLen := new(big.Int)
if expLen.Cmp(big32) > 0 {
adjExpLen.Sub(expLen, big32)
adjExpLen.Mul(big8, adjExpLen)
}
adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))
// Calculate the gas cost of the operation
gas := new(big.Int).Set(math.BigMax(modLen, baseLen))
switch {
case gas.Cmp(big64) <= 0:
gas.Mul(gas, gas)
case gas.Cmp(big1024) <= 0:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big4),
new(big.Int).Sub(new(big.Int).Mul(big96, gas), big3072),
)
default:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big16),
new(big.Int).Sub(new(big.Int).Mul(big480, gas), big199680),
)
}
gas.Mul(gas, math.BigMax(adjExpLen, big1))
gas.Div(gas, new(big.Int).SetUint64(params.ModExpQuadCoeffDiv))
if gas.BitLen() > 64 {
return math.MaxUint64
}
return gas.Uint64()
}
func (c *bigModExp) Run(input []byte) ([]byte, error) {
var (
baseLen = new(big.Int).SetBytes(getData(input, 0, 32)).Uint64()
expLen = new(big.Int).SetBytes(getData(input, 32, 32)).Uint64()
modLen = new(big.Int).SetBytes(getData(input, 64, 32)).Uint64()
)
if len(input) > 96 {
input = input[96:]
} else {
input = input[:0]
}
// Handle a special case when both the base and mod length is zero
if baseLen == 0 && modLen == 0 {
return []byte{}, nil
}
// Retrieve the operands and execute the exponentiation
var (
base = new(big.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
)
if mod.BitLen() == 0 {
// Modulo 0 is undefined, return zero
return common.LeftPadBytes([]byte{}, int(modLen)), nil
}
return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
}
// 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
}
// runBn256Add implements the Bn256Add precompile, referenced by both
// Byzantium and Istanbul operations.
func runBn256Add(input []byte) ([]byte, error) {
x, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
y, err := newCurvePoint(getData(input, 64, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.Add(x, y)
return res.Marshal(), nil
}
// bn256Add implements a native elliptic curve point addition conforming to
// Istanbul consensus rules.
type bn256AddIstanbul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256AddIstanbul) RequiredGas(input []byte) uint64 {
return params.Bn256AddGasIstanbul
}
func (c *bn256AddIstanbul) Run(input []byte) ([]byte, error) {
return runBn256Add(input)
}
// bn256AddByzantium implements a native elliptic curve point addition
// conforming to Byzantium consensus rules.
type bn256AddByzantium struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256AddByzantium) RequiredGas(input []byte) uint64 {
return params.Bn256AddGasByzantium
}
func (c *bn256AddByzantium) Run(input []byte) ([]byte, error) {
return runBn256Add(input)
}
// runBn256ScalarMul implements the Bn256ScalarMul precompile, referenced by
// both Byzantium and Istanbul operations.
func runBn256ScalarMul(input []byte) ([]byte, error) {
p, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.ScalarMult(p, new(big.Int).SetBytes(getData(input, 64, 32)))
return res.Marshal(), nil
}
// bn256ScalarMulIstanbul implements a native elliptic curve scalar
// multiplication conforming to Istanbul consensus rules.
type bn256ScalarMulIstanbul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256ScalarMulIstanbul) RequiredGas(input []byte) uint64 {
return params.Bn256ScalarMulGasIstanbul
}
func (c *bn256ScalarMulIstanbul) Run(input []byte) ([]byte, error) {
return runBn256ScalarMul(input)
}
// bn256ScalarMulByzantium implements a native elliptic curve scalar
// multiplication conforming to Byzantium consensus rules.
type bn256ScalarMulByzantium struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256ScalarMulByzantium) RequiredGas(input []byte) uint64 {
return params.Bn256ScalarMulGasByzantium
}
func (c *bn256ScalarMulByzantium) Run(input []byte) ([]byte, error) {
return runBn256ScalarMul(input)
}
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")
)
// runBn256Pairing implements the Bn256Pairing precompile, referenced by both
// Byzantium and Istanbul operations.
func runBn256Pairing(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
}
// bn256PairingIstanbul implements a pairing pre-compile for the bn256 curve
// conforming to Istanbul consensus rules.
type bn256PairingIstanbul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256PairingIstanbul) RequiredGas(input []byte) uint64 {
return params.Bn256PairingBaseGasIstanbul + uint64(len(input)/192)*params.Bn256PairingPerPointGasIstanbul
}
func (c *bn256PairingIstanbul) Run(input []byte) ([]byte, error) {
return runBn256Pairing(input)
}
// bn256PairingByzantium implements a pairing pre-compile for the bn256 curve
// conforming to Byzantium consensus rules.
type bn256PairingByzantium struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256PairingByzantium) RequiredGas(input []byte) uint64 {
return params.Bn256PairingBaseGasByzantium + uint64(len(input)/192)*params.Bn256PairingPerPointGasByzantium
}
func (c *bn256PairingByzantium) Run(input []byte) ([]byte, error) {
return runBn256Pairing(input)
}
type blake2F struct{}
func (c *blake2F) RequiredGas(input []byte) uint64 {
// If the input is malformed, we can't calculate the gas, return 0 and let the
// actual call choke and fault.
if len(input) != blake2FInputLength {
return 0
}
return uint64(binary.BigEndian.Uint32(input[0:4]))
}
const (
blake2FInputLength = 213
blake2FFinalBlockBytes = byte(1)
blake2FNonFinalBlockBytes = byte(0)
)
var (
errBlake2FInvalidInputLength = errors.New("invalid input length")
errBlake2FInvalidFinalFlag = errors.New("invalid final flag")
)
func (c *blake2F) Run(input []byte) ([]byte, error) {
// Make sure the input is valid (correct length and final flag)
if len(input) != blake2FInputLength {
return nil, errBlake2FInvalidInputLength
}
if input[212] != blake2FNonFinalBlockBytes && input[212] != blake2FFinalBlockBytes {
return nil, errBlake2FInvalidFinalFlag
}
// Parse the input into the Blake2b call parameters
var (
rounds = binary.BigEndian.Uint32(input[0:4])
final = (input[212] == blake2FFinalBlockBytes)
h [8]uint64
m [16]uint64
t [2]uint64
)
for i := 0; i < 8; i++ {
offset := 4 + i*8
h[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
}
for i := 0; i < 16; i++ {
offset := 68 + i*8
m[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
}
t[0] = binary.LittleEndian.Uint64(input[196:204])
t[1] = binary.LittleEndian.Uint64(input[204:212])
// Execute the compression function, extract and return the result
blake2b.F(&h, m, t, final, rounds)
output := make([]byte, 64)
for i := 0; i < 8; i++ {
offset := i * 8
binary.LittleEndian.PutUint64(output[offset:offset+8], h[i])
}
return output, nil
}
var (
errBLS12381InvalidInputLength = errors.New("invalid input length")
errBLS12381InvalidFieldElementTopBytes = errors.New("invalid field element top bytes")
errBLS12381G1PointSubgroup = errors.New("g1 point is not on correct subgroup")
errBLS12381G2PointSubgroup = errors.New("g2 point is not on correct subgroup")
)
// bls12381G1Add implements EIP-2537 G1Add precompile.
type bls12381G1Add struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1Add) RequiredGas(input []byte) uint64 {
return params.Bls12381G1AddGas
}
func (c *bls12381G1Add) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G1Add precompile.
// > G1 addition call expects `256` bytes as an input that is interpreted as byte concatenation of two G1 points (`128` bytes each).
// > Output is an encoding of addition operation result - single G1 point (`128` bytes).
if len(input) != 256 {
return nil, errBLS12381InvalidInputLength
}
var err error
var p0, p1 *bls12381.PointG1
// Initialize G1
g := bls12381.NewG1()
// Decode G1 point p_0
if p0, err = g.DecodePoint(input[:128]); err != nil {
return nil, err
}
// Decode G1 point p_1
if p1, err = g.DecodePoint(input[128:]); err != nil {
return nil, err
}
// Compute r = p_0 + p_1
r := g.New()
g.Add(r, p0, p1)
// Encode the G1 point result into 128 bytes
return g.EncodePoint(r), nil
}
// bls12381G1Mul implements EIP-2537 G1Mul precompile.
type bls12381G1Mul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1Mul) RequiredGas(input []byte) uint64 {
return params.Bls12381G1MulGas
}
func (c *bls12381G1Mul) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G1Mul precompile.
// > G1 multiplication call expects `160` bytes as an input that is interpreted as byte concatenation of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32` bytes).
// > Output is an encoding of multiplication operation result - single G1 point (`128` bytes).
if len(input) != 160 {
return nil, errBLS12381InvalidInputLength
}
var err error
var p0 *bls12381.PointG1
// Initialize G1
g := bls12381.NewG1()
// Decode G1 point
if p0, err = g.DecodePoint(input[:128]); err != nil {
return nil, err
}
// Decode scalar value
e := new(big.Int).SetBytes(input[128:])
// Compute r = e * p_0
r := g.New()
g.MulScalar(r, p0, e)
// Encode the G1 point into 128 bytes
return g.EncodePoint(r), nil
}
// bls12381G1MultiExp implements EIP-2537 G1MultiExp precompile.
type bls12381G1MultiExp struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1MultiExp) RequiredGas(input []byte) uint64 {
// Calculate G1 point, scalar value pair length
k := len(input) / 160
if k == 0 {
// Return 0 gas for small input length
return 0
}
// Lookup discount value for G1 point, scalar value pair length
var discount uint64
if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen {
discount = params.Bls12381MultiExpDiscountTable[k-1]
} else {
discount = params.Bls12381MultiExpDiscountTable[dLen-1]
}
// Calculate gas and return the result
return (uint64(k) * params.Bls12381G1MulGas * discount) / 1000
}
func (c *bls12381G1MultiExp) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G1MultiExp precompile.
// G1 multiplication call expects `160*k` bytes as an input that is interpreted as byte concatenation of `k` slices each of them being a byte concatenation of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32` bytes).
// Output is an encoding of multiexponentiation operation result - single G1 point (`128` bytes).
k := len(input) / 160
if len(input) == 0 || len(input)%160 != 0 {
return nil, errBLS12381InvalidInputLength
}
var err error
points := make([]*bls12381.PointG1, k)
scalars := make([]*big.Int, k)
// Initialize G1
g := bls12381.NewG1()
// Decode point scalar pairs
for i := 0; i < k; i++ {
off := 160 * i
t0, t1, t2 := off, off+128, off+160
// Decode G1 point
if points[i], err = g.DecodePoint(input[t0:t1]); err != nil {
return nil, err
}
// Decode scalar value
scalars[i] = new(big.Int).SetBytes(input[t1:t2])
}
// Compute r = e_0 * p_0 + e_1 * p_1 + ... + e_(k-1) * p_(k-1)
r := g.New()
g.MultiExp(r, points, scalars)
// Encode the G1 point to 128 bytes
return g.EncodePoint(r), nil
}
// bls12381G2Add implements EIP-2537 G2Add precompile.
type bls12381G2Add struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2Add) RequiredGas(input []byte) uint64 {
return params.Bls12381G2AddGas
}
func (c *bls12381G2Add) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G2Add precompile.
// > G2 addition call expects `512` bytes as an input that is interpreted as byte concatenation of two G2 points (`256` bytes each).
// > Output is an encoding of addition operation result - single G2 point (`256` bytes).
if len(input) != 512 {
return nil, errBLS12381InvalidInputLength
}
var err error
var p0, p1 *bls12381.PointG2
// Initialize G2
g := bls12381.NewG2()
r := g.New()
// Decode G2 point p_0
if p0, err = g.DecodePoint(input[:256]); err != nil {
return nil, err
}
// Decode G2 point p_1
if p1, err = g.DecodePoint(input[256:]); err != nil {
return nil, err
}
// Compute r = p_0 + p_1
g.Add(r, p0, p1)
// Encode the G2 point into 256 bytes
return g.EncodePoint(r), nil
}
// bls12381G2Mul implements EIP-2537 G2Mul precompile.
type bls12381G2Mul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2Mul) RequiredGas(input []byte) uint64 {
return params.Bls12381G2MulGas
}
func (c *bls12381G2Mul) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G2MUL precompile logic.
// > G2 multiplication call expects `288` bytes as an input that is interpreted as byte concatenation of encoding of G2 point (`256` bytes) and encoding of a scalar value (`32` bytes).
// > Output is an encoding of multiplication operation result - single G2 point (`256` bytes).
if len(input) != 288 {
return nil, errBLS12381InvalidInputLength
}
var err error
var p0 *bls12381.PointG2
// Initialize G2
g := bls12381.NewG2()
// Decode G2 point
if p0, err = g.DecodePoint(input[:256]); err != nil {
return nil, err
}
// Decode scalar value
e := new(big.Int).SetBytes(input[256:])
// Compute r = e * p_0
r := g.New()
g.MulScalar(r, p0, e)
// Encode the G2 point into 256 bytes
return g.EncodePoint(r), nil
}
// bls12381G2MultiExp implements EIP-2537 G2MultiExp precompile.
type bls12381G2MultiExp struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2MultiExp) RequiredGas(input []byte) uint64 {
// Calculate G2 point, scalar value pair length
k := len(input) / 288
if k == 0 {
// Return 0 gas for small input length
return 0
}
// Lookup discount value for G2 point, scalar value pair length
var discount uint64
if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen {
discount = params.Bls12381MultiExpDiscountTable[k-1]
} else {
discount = params.Bls12381MultiExpDiscountTable[dLen-1]
}
// Calculate gas and return the result
return (uint64(k) * params.Bls12381G2MulGas * discount) / 1000
}
func (c *bls12381G2MultiExp) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 G2MultiExp precompile logic
// > G2 multiplication call expects `288*k` bytes as an input that is interpreted as byte concatenation of `k` slices each of them being a byte concatenation of encoding of G2 point (`256` bytes) and encoding of a scalar value (`32` bytes).
// > Output is an encoding of multiexponentiation operation result - single G2 point (`256` bytes).
k := len(input) / 288
if len(input) == 0 || len(input)%288 != 0 {
return nil, errBLS12381InvalidInputLength
}
var err error
points := make([]*bls12381.PointG2, k)
scalars := make([]*big.Int, k)
// Initialize G2
g := bls12381.NewG2()
// Decode point scalar pairs
for i := 0; i < k; i++ {
off := 288 * i
t0, t1, t2 := off, off+256, off+288
// Decode G1 point
if points[i], err = g.DecodePoint(input[t0:t1]); err != nil {
return nil, err
}
// Decode scalar value
scalars[i] = new(big.Int).SetBytes(input[t1:t2])
}
// Compute r = e_0 * p_0 + e_1 * p_1 + ... + e_(k-1) * p_(k-1)
r := g.New()
g.MultiExp(r, points, scalars)
// Encode the G2 point to 256 bytes.
return g.EncodePoint(r), nil
}
// bls12381Pairing implements EIP-2537 Pairing precompile.
type bls12381Pairing struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381Pairing) RequiredGas(input []byte) uint64 {
return params.Bls12381PairingBaseGas + uint64(len(input)/384)*params.Bls12381PairingPerPairGas
}
func (c *bls12381Pairing) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 Pairing precompile logic.
// > Pairing call expects `384*k` bytes as an inputs that is interpreted as byte concatenation of `k` slices. Each slice has the following structure:
// > - `128` bytes of G1 point encoding
// > - `256` bytes of G2 point encoding
// > Output is a `32` bytes where last single byte is `0x01` if pairing result is equal to multiplicative identity in a pairing target field and `0x00` otherwise
// > (which is equivalent of Big Endian encoding of Solidity values `uint256(1)` and `uin256(0)` respectively).
k := len(input) / 384
if len(input) == 0 || len(input)%384 != 0 {
return nil, errBLS12381InvalidInputLength
}
// Initialize BLS12-381 pairing engine
e := bls12381.NewPairingEngine()
g1, g2 := e.G1, e.G2
// Decode pairs
for i := 0; i < k; i++ {
off := 384 * i
t0, t1, t2 := off, off+128, off+384
// Decode G1 point
p1, err := g1.DecodePoint(input[t0:t1])
if err != nil {
return nil, err
}
// Decode G2 point
p2, err := g2.DecodePoint(input[t1:t2])
if err != nil {
return nil, err
}
// 'point is on curve' check already done,
// Here we need to apply subgroup checks.
if !g1.InCorrectSubgroup(p1) {
return nil, errBLS12381G1PointSubgroup
}
if !g2.InCorrectSubgroup(p2) {
return nil, errBLS12381G2PointSubgroup
}
// Update pairing engine with G1 and G2 ponits
e.AddPair(p1, p2)
}
// Prepare 32 byte output
out := make([]byte, 32)
// Compute pairing and set the result
if e.Check() {
out[31] = 1
}
return out, nil
}
// decodeBLS12381FieldElement decodes BLS12-381 elliptic curve field element.
// Removes top 16 bytes of 64 byte input.
func decodeBLS12381FieldElement(in []byte) ([]byte, error) {
if len(in) != 64 {
return nil, errors.New("invalid field element length")
}
// check top bytes
for i := 0; i < 16; i++ {
if in[i] != byte(0x00) {
return nil, errBLS12381InvalidFieldElementTopBytes
}
}
out := make([]byte, 48)
copy(out[:], in[16:])
return out, nil
}
// bls12381MapG1 implements EIP-2537 MapG1 precompile.
type bls12381MapG1 struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381MapG1) RequiredGas(input []byte) uint64 {
return params.Bls12381MapG1Gas
}
func (c *bls12381MapG1) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 Map_To_G1 precompile.
// > Field-to-curve call expects `64` bytes an an input that is interpreted as a an element of the base field.
// > Output of this call is `128` bytes and is G1 point following respective encoding rules.
if len(input) != 64 {
return nil, errBLS12381InvalidInputLength
}
// Decode input field element
fe, err := decodeBLS12381FieldElement(input)
if err != nil {
return nil, err
}
// Initialize G1
g := bls12381.NewG1()
// Compute mapping
r, err := g.MapToCurve(fe)
if err != nil {
return nil, err
}
// Encode the G1 point to 128 bytes
return g.EncodePoint(r), nil
}
// bls12381MapG2 implements EIP-2537 MapG2 precompile.
type bls12381MapG2 struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381MapG2) RequiredGas(input []byte) uint64 {
return params.Bls12381MapG2Gas
}
func (c *bls12381MapG2) Run(input []byte) ([]byte, error) {
// Implements EIP-2537 Map_FP2_TO_G2 precompile logic.
// > Field-to-curve call expects `128` bytes an an input that is interpreted as a an element of the quadratic extension field.
// > Output of this call is `256` bytes and is G2 point following respective encoding rules.
if len(input) != 128 {
return nil, errBLS12381InvalidInputLength
}
// Decode input field element
fe := make([]byte, 96)
c0, err := decodeBLS12381FieldElement(input[:64])
if err != nil {
return nil, err
}
copy(fe[48:], c0)
c1, err := decodeBLS12381FieldElement(input[64:])
if err != nil {
return nil, err
}
copy(fe[:48], c1)
// Initialize G2
g := bls12381.NewG2()
// Compute mapping
r, err := g.MapToCurve(fe)
if err != nil {
return nil, err
}
// Encode the G2 point to 256 bytes
return g.EncodePoint(r), nil
}
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