380 lines
12 KiB
Go
380 lines
12 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"crypto/sha256"
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"errors"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/math"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/bn256"
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"github.com/ethereum/go-ethereum/params"
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"golang.org/x/crypto/ripemd160"
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)
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// PrecompiledContract is the basic interface for native Go contracts. The implementation
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// requires a deterministic gas count based on the input size of the Run method of the
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// contract.
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type PrecompiledContract interface {
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RequiredGas(input []byte) uint64 // RequiredPrice calculates the contract gas use
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Run(input []byte) ([]byte, error) // Run runs the precompiled contract
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}
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// PrecompiledContractsHomestead contains the default set of pre-compiled Ethereum
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// contracts used in the Frontier and Homestead releases.
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var PrecompiledContractsHomestead = map[common.Address]PrecompiledContract{
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common.BytesToAddress([]byte{1}): &ecrecover{},
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common.BytesToAddress([]byte{2}): &sha256hash{},
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common.BytesToAddress([]byte{3}): &ripemd160hash{},
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common.BytesToAddress([]byte{4}): &dataCopy{},
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}
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// PrecompiledContractsMetropolis contains the default set of pre-compiled Ethereum
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// contracts used in the Metropolis release.
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var PrecompiledContractsMetropolis = map[common.Address]PrecompiledContract{
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common.BytesToAddress([]byte{1}): &ecrecover{},
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common.BytesToAddress([]byte{2}): &sha256hash{},
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common.BytesToAddress([]byte{3}): &ripemd160hash{},
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common.BytesToAddress([]byte{4}): &dataCopy{},
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common.BytesToAddress([]byte{5}): &bigModExp{},
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common.BytesToAddress([]byte{6}): &bn256Add{},
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common.BytesToAddress([]byte{7}): &bn256ScalarMul{},
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common.BytesToAddress([]byte{8}): &bn256Pairing{},
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}
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// RunPrecompiledContract runs and evaluates the output of a precompiled contract.
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func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
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gas := p.RequiredGas(input)
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if contract.UseGas(gas) {
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return p.Run(input)
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}
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return nil, ErrOutOfGas
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}
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// ECRECOVER implemented as a native contract.
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type ecrecover struct{}
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func (c *ecrecover) RequiredGas(input []byte) uint64 {
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return params.EcrecoverGas
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}
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func (c *ecrecover) Run(input []byte) ([]byte, error) {
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const ecRecoverInputLength = 128
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input = common.RightPadBytes(input, ecRecoverInputLength)
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// "input" is (hash, v, r, s), each 32 bytes
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// but for ecrecover we want (r, s, v)
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r := new(big.Int).SetBytes(input[64:96])
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s := new(big.Int).SetBytes(input[96:128])
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v := input[63] - 27
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// tighter sig s values input homestead only apply to tx sigs
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if !allZero(input[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
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return nil, nil
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}
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// v needs to be at the end for libsecp256k1
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pubKey, err := crypto.Ecrecover(input[:32], append(input[64:128], v))
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// make sure the public key is a valid one
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if err != nil {
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return nil, nil
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}
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// the first byte of pubkey is bitcoin heritage
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return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
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}
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// SHA256 implemented as a native contract.
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type sha256hash struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *sha256hash) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.Sha256PerWordGas + params.Sha256BaseGas
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}
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func (c *sha256hash) Run(input []byte) ([]byte, error) {
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h := sha256.Sum256(input)
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return h[:], nil
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}
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// RIPMED160 implemented as a native contract.
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type ripemd160hash struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.Ripemd160PerWordGas + params.Ripemd160BaseGas
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}
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func (c *ripemd160hash) Run(input []byte) ([]byte, error) {
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ripemd := ripemd160.New()
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ripemd.Write(input)
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return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
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}
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// data copy implemented as a native contract.
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type dataCopy struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *dataCopy) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.IdentityPerWordGas + params.IdentityBaseGas
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}
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func (c *dataCopy) Run(in []byte) ([]byte, error) {
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return in, nil
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}
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// bigModExp implements a native big integer exponential modular operation.
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type bigModExp struct{}
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var (
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big1 = big.NewInt(1)
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big4 = big.NewInt(4)
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big8 = big.NewInt(8)
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big16 = big.NewInt(16)
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big32 = big.NewInt(32)
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big64 = big.NewInt(64)
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big96 = big.NewInt(96)
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big480 = big.NewInt(480)
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big1024 = big.NewInt(1024)
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big3072 = big.NewInt(3072)
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big199680 = big.NewInt(199680)
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)
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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func (c *bigModExp) RequiredGas(input []byte) uint64 {
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var (
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baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
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expLen = new(big.Int).SetBytes(getData(input, 32, 32))
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modLen = new(big.Int).SetBytes(getData(input, 64, 32))
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)
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if len(input) > 96 {
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input = input[96:]
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} else {
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input = input[:0]
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}
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// Retrieve the head 32 bytes of exp for the adjusted exponent length
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var expHead *big.Int
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if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
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expHead = new(big.Int)
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} else {
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if expLen.Cmp(big32) > 0 {
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expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
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} else {
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expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
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}
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}
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// Calculate the adjusted exponent length
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var msb int
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if bitlen := expHead.BitLen(); bitlen > 0 {
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msb = bitlen - 1
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}
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adjExpLen := new(big.Int)
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if expLen.Cmp(big32) > 0 {
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adjExpLen.Sub(expLen, big32)
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adjExpLen.Mul(big8, adjExpLen)
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}
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adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))
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// Calculate the gas cost of the operation
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gas := new(big.Int).Set(math.BigMax(modLen, baseLen))
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switch {
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case gas.Cmp(big64) <= 0:
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gas.Mul(gas, gas)
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case gas.Cmp(big1024) <= 0:
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gas = new(big.Int).Add(
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new(big.Int).Div(new(big.Int).Mul(gas, gas), big4),
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new(big.Int).Sub(new(big.Int).Mul(big96, gas), big3072),
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)
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default:
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gas = new(big.Int).Add(
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new(big.Int).Div(new(big.Int).Mul(gas, gas), big16),
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new(big.Int).Sub(new(big.Int).Mul(big480, gas), big199680),
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)
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}
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gas.Mul(gas, math.BigMax(adjExpLen, big1))
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gas.Div(gas, new(big.Int).SetUint64(params.ModExpQuadCoeffDiv))
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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return gas.Uint64()
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}
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func (c *bigModExp) Run(input []byte) ([]byte, error) {
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var (
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baseLen = new(big.Int).SetBytes(getData(input, 0, 32)).Uint64()
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expLen = new(big.Int).SetBytes(getData(input, 32, 32)).Uint64()
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modLen = new(big.Int).SetBytes(getData(input, 64, 32)).Uint64()
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)
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if len(input) > 96 {
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input = input[96:]
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} else {
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input = input[:0]
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}
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// Handle a special case when both the base and mod length is zero
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if baseLen == 0 && modLen == 0 {
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return []byte{}, nil
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}
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// Retrieve the operands and execute the exponentiation
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var (
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base = new(big.Int).SetBytes(getData(input, 0, baseLen))
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exp = new(big.Int).SetBytes(getData(input, baseLen, expLen))
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mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
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)
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if mod.BitLen() == 0 {
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// Modulo 0 is undefined, return zero
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return common.LeftPadBytes([]byte{}, int(modLen)), nil
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}
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return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
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}
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var (
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// errNotOnCurve is returned if a point being unmarshalled as a bn256 elliptic
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// curve point is not on the curve.
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errNotOnCurve = errors.New("point not on elliptic curve")
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// errInvalidCurvePoint is returned if a point being unmarshalled as a bn256
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// elliptic curve point is invalid.
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errInvalidCurvePoint = errors.New("invalid elliptic curve point")
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)
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// newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point,
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// returning it, or an error if the point is invalid.
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func newCurvePoint(blob []byte) (*bn256.G1, error) {
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p, onCurve := new(bn256.G1).Unmarshal(blob)
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if !onCurve {
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return nil, errNotOnCurve
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}
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gx, gy, _, _ := p.CurvePoints()
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if gx.Cmp(bn256.P) >= 0 || gy.Cmp(bn256.P) >= 0 {
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return nil, errInvalidCurvePoint
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}
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return p, nil
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}
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// newTwistPoint unmarshals a binary blob into a bn256 elliptic curve point,
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// returning it, or an error if the point is invalid.
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func newTwistPoint(blob []byte) (*bn256.G2, error) {
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p, onCurve := new(bn256.G2).Unmarshal(blob)
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if !onCurve {
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return nil, errNotOnCurve
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}
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x2, y2, _, _ := p.CurvePoints()
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if x2.Real().Cmp(bn256.P) >= 0 || x2.Imag().Cmp(bn256.P) >= 0 ||
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y2.Real().Cmp(bn256.P) >= 0 || y2.Imag().Cmp(bn256.P) >= 0 {
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return nil, errInvalidCurvePoint
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}
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return p, nil
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}
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// bn256Add implements a native elliptic curve point addition.
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type bn256Add struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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func (c *bn256Add) RequiredGas(input []byte) uint64 {
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return params.Bn256AddGas
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}
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func (c *bn256Add) Run(input []byte) ([]byte, error) {
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x, err := newCurvePoint(getData(input, 0, 64))
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if err != nil {
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return nil, err
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}
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y, err := newCurvePoint(getData(input, 64, 64))
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if err != nil {
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return nil, err
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}
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res := new(bn256.G1)
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res.Add(x, y)
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return res.Marshal(), nil
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}
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// bn256ScalarMul implements a native elliptic curve scalar multiplication.
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type bn256ScalarMul struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
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return params.Bn256ScalarMulGas
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}
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func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
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p, err := newCurvePoint(getData(input, 0, 64))
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if err != nil {
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return nil, err
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}
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res := new(bn256.G1)
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res.ScalarMult(p, new(big.Int).SetBytes(getData(input, 64, 32)))
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return res.Marshal(), nil
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}
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var (
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// true32Byte is returned if the bn256 pairing check succeeds.
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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}
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// false32Byte is returned if the bn256 pairing check fails.
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false32Byte = make([]byte, 32)
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// errBadPairingInput is returned if the bn256 pairing input is invalid.
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errBadPairingInput = errors.New("bad elliptic curve pairing size")
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)
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// bn256Pairing implements a pairing pre-compile for the bn256 curve
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type bn256Pairing struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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func (c *bn256Pairing) RequiredGas(input []byte) uint64 {
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return params.Bn256PairingBaseGas + uint64(len(input)/192)*params.Bn256PairingPerPointGas
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}
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func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
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// Handle some corner cases cheaply
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if len(input)%192 > 0 {
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return nil, errBadPairingInput
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}
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// Convert the input into a set of coordinates
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var (
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cs []*bn256.G1
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ts []*bn256.G2
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)
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for i := 0; i < len(input); i += 192 {
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c, err := newCurvePoint(input[i : i+64])
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if err != nil {
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return nil, err
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}
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t, err := newTwistPoint(input[i+64 : i+192])
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if err != nil {
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return nil, err
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}
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cs = append(cs, c)
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ts = append(ts, t)
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}
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// Execute the pairing checks and return the results
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if bn256.PairingCheck(cs, ts) {
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return true32Byte, nil
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}
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return false32Byte, nil
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}
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