core/vm: polish precompile contract code, add tests and benches
* Update modexp gas calculation to new version * Fix modexp modulo 0 special case to return zero
This commit is contained in:
Péter Szilágyi
@ -29,9 +29,7 @@ import (
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"golang.org/x/crypto/ripemd160"
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)
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var errBadPrecompileInput = errors.New("bad pre compile input")
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// Precompiled contract is the basic interface for native Go contracts. The implementation
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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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@ -39,61 +37,61 @@ type PrecompiledContract interface {
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Run(input []byte) ([]byte, error) // Run runs the precompiled contract
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}
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// PrecompiledContracts contains the default set of ethereum contracts
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var PrecompiledContracts = map[common.Address]PrecompiledContract{
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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 ethereum contracts
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// for metropolis hardfork
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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{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}): &pairing{},
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common.BytesToAddress([]byte{8}): &bn256Pairing{},
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}
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// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
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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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} else {
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return nil, ErrOutOfGas
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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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// 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(in []byte) ([]byte, error) {
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func (c *ecrecover) Run(input []byte) ([]byte, error) {
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const ecRecoverInputLength = 128
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in = common.RightPadBytes(in, ecRecoverInputLength)
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// "in" is (hash, v, r, s), each 32 bytes
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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(in[64:96])
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s := new(big.Int).SetBytes(in[96:128])
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v := in[63] - 27
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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 in homestead only apply to tx sigs
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if !allZero(in[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
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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(in[:32], append(in[64:128], v))
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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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@ -103,7 +101,7 @@ func (c *ecrecover) Run(in []byte) ([]byte, error) {
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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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// 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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@ -111,14 +109,14 @@ type sha256hash struct{}
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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.Sha256WordGas + params.Sha256Gas
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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(in []byte) ([]byte, error) {
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h := sha256.Sum256(in)
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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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// 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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@ -126,15 +124,15 @@ type ripemd160hash struct{}
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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.Ripemd160WordGas + params.Ripemd160Gas
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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(in []byte) ([]byte, error) {
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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(in)
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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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// 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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@ -142,195 +140,232 @@ type dataCopy struct{}
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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.IdentityWordGas + params.IdentityGas
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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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// bigModExp implements a native big integer exponential modular operation.
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type bigModExp 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 *bigModexp) RequiredGas(input []byte) uint64 {
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// TODO reword required gas to have error reporting and convert arithmetic
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// to uint64.
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if len(input) < 3*32 {
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input = append(input, make([]byte, 3*32-len(input))...)
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}
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var (
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baseLen = new(big.Int).SetBytes(input[:31])
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expLen = math.BigMax(new(big.Int).SetBytes(input[32:64]), big.NewInt(1))
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modLen = new(big.Int).SetBytes(input[65:97])
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)
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x := new(big.Int).Set(math.BigMax(baseLen, modLen))
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x.Mul(x, x)
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x.Mul(x, expLen)
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x.Div(x, new(big.Int).SetUint64(params.QuadCoeffDiv))
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func (c *bigModExp) RequiredGas(input []byte) uint64 {
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// Pad the input with zeroes to the minimum size to read the field lengths
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input = common.RightPadBytes(input, 96)
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return x.Uint64()
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var (
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baseLen = new(big.Int).SetBytes(input[:32])
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expLen = new(big.Int).SetBytes(input[32:64])
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modLen = new(big.Int).SetBytes(input[64:96])
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)
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input = input[96:]
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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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offset := int(baseLen.Uint64())
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input = common.RightPadBytes(input, offset+32)
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if expLen.Cmp(big.NewInt(32)) > 0 {
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expHead = new(big.Int).SetBytes(input[offset : offset+32])
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} else {
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expHead = new(big.Int).SetBytes(input[offset : offset+int(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(big.NewInt(32)) > 0 {
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adjExpLen.Sub(expLen, big.NewInt(32))
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adjExpLen.Mul(big.NewInt(8), 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(big.NewInt(64)) <= 0:
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gas.Mul(gas, gas)
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case gas.Cmp(big.NewInt(1024)) <= 0:
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gas = new(big.Int).Add(
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new(big.Int).Div(new(big.Int).Mul(gas, gas), big.NewInt(4)),
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new(big.Int).Sub(new(big.Int).Mul(big.NewInt(96), gas), big.NewInt(3072)),
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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), big.NewInt(16)),
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new(big.Int).Sub(new(big.Int).Mul(big.NewInt(480), gas), big.NewInt(199680)),
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)
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}
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gas.Mul(gas, math.BigMax(adjExpLen, big.NewInt(1)))
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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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if len(input) < 3*32 {
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input = append(input, make([]byte, 3*32-len(input))...)
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}
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// why 32-byte? These values won't fit anyway
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func (c *bigModExp) Run(input []byte) ([]byte, error) {
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// Pad the input with zeroes to the minimum size to read the field lengths
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input = common.RightPadBytes(input, 96)
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var (
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baseLen = new(big.Int).SetBytes(input[:32]).Uint64()
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expLen = new(big.Int).SetBytes(input[32:64]).Uint64()
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modLen = new(big.Int).SetBytes(input[64:96]).Uint64()
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)
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input = input[96:]
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if uint64(len(input)) < baseLen {
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input = append(input, make([]byte, baseLen-uint64(len(input)))...)
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}
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base := new(big.Int).SetBytes(input[:baseLen])
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input = input[baseLen:]
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if uint64(len(input)) < expLen {
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input = append(input, make([]byte, expLen-uint64(len(input)))...)
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}
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exp := new(big.Int).SetBytes(input[:expLen])
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// Pad the input with zeroes to the minimum size to read the field contents
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input = common.RightPadBytes(input, int(baseLen+expLen+modLen))
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input = input[expLen:]
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if uint64(len(input)) < modLen {
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input = append(input, make([]byte, modLen-uint64(len(input)))...)
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var (
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base = new(big.Int).SetBytes(input[:baseLen])
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exp = new(big.Int).SetBytes(input[baseLen : baseLen+expLen])
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mod = new(big.Int).SetBytes(input[baseLen+expLen : 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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mod := new(big.Int).SetBytes(input[:modLen])
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return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), len(input[:modLen])), nil
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return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
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}
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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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//
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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 *bn256Add) RequiredGas(input []byte) uint64 {
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return 0 // TODO
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}
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func (c *bn256Add) Run(in []byte) ([]byte, error) {
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in = common.RightPadBytes(in, 128)
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x, onCurve := new(bn256.G1).Unmarshal(in[:64])
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if !onCurve {
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return nil, errNotOnCurve
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}
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gx, gy, _, _ := x.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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y, onCurve := new(bn256.G1).Unmarshal(in[64:128])
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if !onCurve {
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return nil, errNotOnCurve
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}
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gx, gy, _, _ = y.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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x.Add(x, y)
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return x.Marshal(), nil
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}
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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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//
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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 *bn256ScalarMul) RequiredGas(input []byte) uint64 {
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return 0 // TODO
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}
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func (c *bn256ScalarMul) Run(in []byte) ([]byte, error) {
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in = common.RightPadBytes(in, 96)
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g1, onCurve := new(bn256.G1).Unmarshal(in[:64])
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if !onCurve {
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return nil, errNotOnCurve
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}
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x, y, _, _ := g1.CurvePoints()
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if x.Cmp(bn256.P) >= 0 || y.Cmp(bn256.P) >= 0 {
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return nil, errInvalidCurvePoint
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}
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g1.ScalarMult(g1, new(big.Int).SetBytes(in[64:96]))
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return g1.Marshal(), nil
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}
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// pairing implements a pairing pre-compile for the bn256 curve
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type pairing 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 *pairing) RequiredGas(input []byte) uint64 {
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//return 0 // TODO
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k := (len(input) + 191) / pairSize
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return uint64(60000*k + 40000)
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}
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const pairSize = 192
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var (
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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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fals32Byte = make([]byte, 32)
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errNotOnCurve = errors.New("point not on elliptic curve")
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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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func (c *pairing) Run(in []byte) ([]byte, error) {
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if len(in) == 0 {
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return true32Byte, nil
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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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if len(in)%pairSize > 0 {
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return nil, errBadPrecompileInput
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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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var (
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g1s []*bn256.G1
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g2s []*bn256.G2
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)
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for i := 0; i < len(in); i += pairSize {
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g1, onCurve := new(bn256.G1).Unmarshal(in[i : i+64])
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if !onCurve {
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return nil, errNotOnCurve
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}
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x, y, _, _ := g1.CurvePoints()
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if x.Cmp(bn256.P) >= 0 || y.Cmp(bn256.P) >= 0 {
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return nil, errInvalidCurvePoint
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}
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g2, onCurve := new(bn256.G2).Unmarshal(in[i+64 : i+192])
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if !onCurve {
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return nil, errNotOnCurve
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}
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x2, y2, _, _ := g2.CurvePoints()
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if x2.Real().Cmp(bn256.P) >= 0 || x2.Imag().Cmp(bn256.P) >= 0 ||
|
||||
y2.Real().Cmp(bn256.P) >= 0 || y2.Imag().Cmp(bn256.P) >= 0 {
|
||||
return nil, errInvalidCurvePoint
|
||||
}
|
||||
|
||||
g1s = append(g1s, g1)
|
||||
g2s = append(g2s, g2)
|
||||
}
|
||||
|
||||
isOne := bn256.PairingCheck(g1s, g2s)
|
||||
if isOne {
|
||||
return true32Byte, nil
|
||||
}
|
||||
|
||||
return fals32Byte, nil
|
||||
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, onCurve := new(bn256.G2).Unmarshal(blob)
|
||||
if !onCurve {
|
||||
return nil, errNotOnCurve
|
||||
}
|
||||
x2, y2, _, _ := p.CurvePoints()
|
||||
if x2.Real().Cmp(bn256.P) >= 0 || x2.Imag().Cmp(bn256.P) >= 0 ||
|
||||
y2.Real().Cmp(bn256.P) >= 0 || y2.Imag().Cmp(bn256.P) >= 0 {
|
||||
return nil, errInvalidCurvePoint
|
||||
}
|
||||
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) {
|
||||
// Ensure we have enough data to operate on
|
||||
input = common.RightPadBytes(input, 128)
|
||||
|
||||
x, err := newCurvePoint(input[:64])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
y, err := newCurvePoint(input[64:128])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
x.Add(x, y)
|
||||
return x.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) {
|
||||
// Ensure we have enough data to operate on
|
||||
input = common.RightPadBytes(input, 96)
|
||||
|
||||
p, err := newCurvePoint(input[:64])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
p.ScalarMult(p, new(big.Int).SetBytes(input[64:96]))
|
||||
return p.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")
|
||||
)
|
||||
|
||||
// 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
|
||||
ok := bn256.PairingCheck(cs, ts)
|
||||
if ok {
|
||||
return true32Byte, nil
|
||||
}
|
||||
return false32Byte, nil
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user