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

core/vm/contracts.go

@@ -29,9 +29,7 @@ import (
 	"golang.org/x/crypto/ripemd160"
 )
 
-var errBadPrecompileInput = errors.New("bad pre compile input")
-
-// Precompiled contract is the basic interface for native Go contracts. The implementation
+// 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 {
@@ -39,61 +37,61 @@ type PrecompiledContract interface {
 	Run(input []byte) ([]byte, error) // Run runs the precompiled contract
 }
 
-// PrecompiledContracts contains the default set of ethereum contracts
-var PrecompiledContracts = map[common.Address]PrecompiledContract{
+// 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{},
 }
 
-// PrecompiledContractsMetropolis contains the default set of ethereum contracts
-// for metropolis hardfork
+// PrecompiledContractsMetropolis contains the default set of pre-compiled Ethereum
+// contracts used in the Metropolis release.
 var PrecompiledContractsMetropolis = 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{5}): &bigModExp{},
 	common.BytesToAddress([]byte{6}): &bn256Add{},
 	common.BytesToAddress([]byte{7}): &bn256ScalarMul{},
-	common.BytesToAddress([]byte{8}): &pairing{},
+	common.BytesToAddress([]byte{8}): &bn256Pairing{},
 }
 
-// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
+// RunPrecompiledContract runs and evaluates the output of a precompiled contract.
 func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
 	gas := p.RequiredGas(input)
 	if contract.UseGas(gas) {
 		return p.Run(input)
-	} else {
-		return nil, ErrOutOfGas
 	}
+	return nil, ErrOutOfGas
 }
 
-// ECRECOVER implemented as a native contract
+// ECRECOVER implemented as a native contract.
 type ecrecover struct{}
 
 func (c *ecrecover) RequiredGas(input []byte) uint64 {
 	return params.EcrecoverGas
 }
 
-func (c *ecrecover) Run(in []byte) ([]byte, error) {
+func (c *ecrecover) Run(input []byte) ([]byte, error) {
 	const ecRecoverInputLength = 128
 
-	in = common.RightPadBytes(in, ecRecoverInputLength)
-	// "in" is (hash, v, r, s), each 32 bytes
+	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(in[64:96])
-	s := new(big.Int).SetBytes(in[96:128])
-	v := in[63] - 27
+	r := new(big.Int).SetBytes(input[64:96])
+	s := new(big.Int).SetBytes(input[96:128])
+	v := input[63] - 27
 
-	// tighter sig s values in homestead only apply to tx sigs
-	if !allZero(in[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
+	// 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
 	}
 	// v needs to be at the end for libsecp256k1
-	pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v))
+	pubKey, err := crypto.Ecrecover(input[:32], append(input[64:128], v))
 	// make sure the public key is a valid one
 	if err != nil {
 		return nil, nil
@@ -103,7 +101,7 @@ func (c *ecrecover) Run(in []byte) ([]byte, error) {
 	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
 }
 
-// SHA256 implemented as a native contract
+// SHA256 implemented as a native contract.
 type sha256hash struct{}
 
 // RequiredGas returns the gas required to execute the pre-compiled contract.
@@ -111,14 +109,14 @@ type sha256hash struct{}
 // 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.Sha256WordGas + params.Sha256Gas
+	return uint64(len(input)+31)/32*params.Sha256PerWordGas + params.Sha256BaseGas
 }
-func (c *sha256hash) Run(in []byte) ([]byte, error) {
-	h := sha256.Sum256(in)
+func (c *sha256hash) Run(input []byte) ([]byte, error) {
+	h := sha256.Sum256(input)
 	return h[:], nil
 }
 
-// RIPMED160 implemented as a native contract
+// RIPMED160 implemented as a native contract.
 type ripemd160hash struct{}
 
 // RequiredGas returns the gas required to execute the pre-compiled contract.
@@ -126,15 +124,15 @@ type ripemd160hash struct{}
 // 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.Ripemd160WordGas + params.Ripemd160Gas
+	return uint64(len(input)+31)/32*params.Ripemd160PerWordGas + params.Ripemd160BaseGas
 }
-func (c *ripemd160hash) Run(in []byte) ([]byte, error) {
+func (c *ripemd160hash) Run(input []byte) ([]byte, error) {
 	ripemd := ripemd160.New()
-	ripemd.Write(in)
+	ripemd.Write(input)
 	return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
 }
 
-// data copy implemented as a native contract
+// data copy implemented as a native contract.
 type dataCopy struct{}
 
 // RequiredGas returns the gas required to execute the pre-compiled contract.
@@ -142,195 +140,232 @@ type dataCopy struct{}
 // 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.IdentityWordGas + params.IdentityGas
+	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{}
+// bigModExp implements a native big integer exponential modular operation.
+type bigModExp 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 *bigModexp) RequiredGas(input []byte) uint64 {
-	// TODO reword required gas to have error reporting and convert arithmetic
-	// to uint64.
-	if len(input) < 3*32 {
-		input = append(input, make([]byte, 3*32-len(input))...)
-	}
+func (c *bigModExp) RequiredGas(input []byte) uint64 {
+	// Pad the input with zeroes to the minimum size to read the field lengths
+	input = common.RightPadBytes(input, 96)
+
 	var (
-		baseLen = new(big.Int).SetBytes(input[:31])
-		expLen  = math.BigMax(new(big.Int).SetBytes(input[32:64]), big.NewInt(1))
-		modLen  = new(big.Int).SetBytes(input[65:97])
+		baseLen = new(big.Int).SetBytes(input[:32])
+		expLen  = new(big.Int).SetBytes(input[32:64])
+		modLen  = new(big.Int).SetBytes(input[64:96])
 	)
-	x := new(big.Int).Set(math.BigMax(baseLen, modLen))
-	x.Mul(x, x)
-	x.Mul(x, expLen)
-	x.Div(x, new(big.Int).SetUint64(params.QuadCoeffDiv))
+	input = input[96:]
 
-	return x.Uint64()
-}
+	// 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 {
+		offset := int(baseLen.Uint64())
 
-func (c *bigModexp) Run(input []byte) ([]byte, error) {
-	if len(input) < 3*32 {
-		input = append(input, make([]byte, 3*32-len(input))...)
+		input = common.RightPadBytes(input, offset+32)
+		if expLen.Cmp(big.NewInt(32)) > 0 {
+			expHead = new(big.Int).SetBytes(input[offset : offset+32])
+		} else {
+			expHead = new(big.Int).SetBytes(input[offset : offset+int(expLen.Uint64())])
+		}
 	}
-	// why 32-byte? These values won't fit anyway
+	// Calculate the adjusted exponent length
+	var msb int
+	if bitlen := expHead.BitLen(); bitlen > 0 {
+		msb = bitlen - 1
+	}
+	adjExpLen := new(big.Int)
+	if expLen.Cmp(big.NewInt(32)) > 0 {
+		adjExpLen.Sub(expLen, big.NewInt(32))
+		adjExpLen.Mul(big.NewInt(8), 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(big.NewInt(64)) <= 0:
+		gas.Mul(gas, gas)
+	case gas.Cmp(big.NewInt(1024)) <= 0:
+		gas = new(big.Int).Add(
+			new(big.Int).Div(new(big.Int).Mul(gas, gas), big.NewInt(4)),
+			new(big.Int).Sub(new(big.Int).Mul(big.NewInt(96), gas), big.NewInt(3072)),
+		)
+	default:
+		gas = new(big.Int).Add(
+			new(big.Int).Div(new(big.Int).Mul(gas, gas), big.NewInt(16)),
+			new(big.Int).Sub(new(big.Int).Mul(big.NewInt(480), gas), big.NewInt(199680)),
+		)
+	}
+	gas.Mul(gas, math.BigMax(adjExpLen, big.NewInt(1)))
+	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) {
+	// Pad the input with zeroes to the minimum size to read the field lengths
+	input = common.RightPadBytes(input, 96)
+
 	var (
 		baseLen = new(big.Int).SetBytes(input[:32]).Uint64()
 		expLen  = new(big.Int).SetBytes(input[32:64]).Uint64()
 		modLen  = new(big.Int).SetBytes(input[64:96]).Uint64()
 	)
-
 	input = input[96:]
-	if uint64(len(input)) < baseLen {
-		input = append(input, make([]byte, baseLen-uint64(len(input)))...)
-	}
-	base := new(big.Int).SetBytes(input[:baseLen])
 
-	input = input[baseLen:]
-	if uint64(len(input)) < expLen {
-		input = append(input, make([]byte, expLen-uint64(len(input)))...)
-	}
-	exp := new(big.Int).SetBytes(input[:expLen])
+	// Pad the input with zeroes to the minimum size to read the field contents
+	input = common.RightPadBytes(input, int(baseLen+expLen+modLen))
 
-	input = input[expLen:]
-	if uint64(len(input)) < modLen {
-		input = append(input, make([]byte, modLen-uint64(len(input)))...)
+	var (
+		base = new(big.Int).SetBytes(input[:baseLen])
+		exp  = new(big.Int).SetBytes(input[baseLen : baseLen+expLen])
+		mod  = new(big.Int).SetBytes(input[baseLen+expLen : baseLen+expLen+modLen])
+	)
+	if mod.BitLen() == 0 {
+		// Modulo 0 is undefined, return zero
+		return common.LeftPadBytes([]byte{}, int(modLen)), nil
 	}
-	mod := new(big.Int).SetBytes(input[:modLen])
-
-	return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), len(input[:modLen])), nil
+	return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
 }
 
-type bn256Add 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 *bn256Add) RequiredGas(input []byte) uint64 {
-	return 0 // TODO
-}
+var (
+	// errNotOnCurve is returned if a point being unmarshalled as a bn256 elliptic
+	// curve point is not on the curve.
+	errNotOnCurve = errors.New("point not on elliptic curve")
 
-func (c *bn256Add) Run(in []byte) ([]byte, error) {
-	in = common.RightPadBytes(in, 128)
+	// errInvalidCurvePoint is returned if a point being unmarshalled as a bn256
+	// elliptic curve point is invalid.
+	errInvalidCurvePoint = errors.New("invalid elliptic curve point")
+)
 
-	x, onCurve := new(bn256.G1).Unmarshal(in[:64])
+// 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, onCurve := new(bn256.G1).Unmarshal(blob)
 	if !onCurve {
 		return nil, errNotOnCurve
 	}
-	gx, gy, _, _ := x.CurvePoints()
+	gx, gy, _, _ := p.CurvePoints()
 	if gx.Cmp(bn256.P) >= 0 || gy.Cmp(bn256.P) >= 0 {
 		return nil, errInvalidCurvePoint
 	}
+	return p, nil
+}
 
-	y, onCurve := new(bn256.G1).Unmarshal(in[64:128])
+// 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
 	}
-	gx, gy, _, _ = y.CurvePoints()
-	if gx.Cmp(bn256.P) >= 0 || gy.Cmp(bn256.P) >= 0 {
+	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
 	}
-	x.Add(x, y)
-
-	return x.Marshal(), nil
+	return p, nil
 }
 
-type bn256ScalarMul struct{}
+// bn256Add implements a native elliptic curve point addition.
+type bn256Add 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 *bn256ScalarMul) RequiredGas(input []byte) uint64 {
-	return 0 // TODO
+func (c *bn256Add) RequiredGas(input []byte) uint64 {
+	return params.Bn256AddGas
 }
 
-func (c *bn256ScalarMul) Run(in []byte) ([]byte, error) {
-	in = common.RightPadBytes(in, 96)
+func (c *bn256Add) Run(input []byte) ([]byte, error) {
+	// Ensure we have enough data to operate on
+	input = common.RightPadBytes(input, 128)
 
-	g1, onCurve := new(bn256.G1).Unmarshal(in[:64])
-	if !onCurve {
-		return nil, errNotOnCurve
+	x, err := newCurvePoint(input[:64])
+	if err != nil {
+		return nil, err
 	}
-	x, y, _, _ := g1.CurvePoints()
-	if x.Cmp(bn256.P) >= 0 || y.Cmp(bn256.P) >= 0 {
-		return nil, errInvalidCurvePoint
+	y, err := newCurvePoint(input[64:128])
+	if err != nil {
+		return nil, err
 	}
-	g1.ScalarMult(g1, new(big.Int).SetBytes(in[64:96]))
-
-	return g1.Marshal(), nil
+	x.Add(x, y)
+	return x.Marshal(), nil
 }
 
-// pairing implements a pairing pre-compile for the bn256 curve
-type pairing struct{}
+// bn256ScalarMul implements a native elliptic curve scalar multiplication.
+type bn256ScalarMul 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 *pairing) RequiredGas(input []byte) uint64 {
-	//return 0 // TODO
-	k := (len(input) + 191) / pairSize
-	return uint64(60000*k + 40000)
+func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
+	return params.Bn256ScalarMulGas
 }
 
-const pairSize = 192
+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           = []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}
-	fals32Byte           = make([]byte, 32)
-	errNotOnCurve        = errors.New("point not on elliptic curve")
-	errInvalidCurvePoint = errors.New("invalid elliptic curve point")
+	// 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")
 )
 
-func (c *pairing) Run(in []byte) ([]byte, error) {
-	if len(in) == 0 {
-		return true32Byte, nil
-	}
+// bn256Pairing implements a pairing pre-compile for the bn256 curve
+type bn256Pairing struct{}
 
-	if len(in)%pairSize > 0 {
-		return nil, errBadPrecompileInput
-	}
+// 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 (
-		g1s []*bn256.G1
-		g2s []*bn256.G2
+		cs []*bn256.G1
+		ts []*bn256.G2
 	)
-	for i := 0; i < len(in); i += pairSize {
-		g1, onCurve := new(bn256.G1).Unmarshal(in[i : i+64])
-		if !onCurve {
-			return nil, errNotOnCurve
-		}
-
-		x, y, _, _ := g1.CurvePoints()
-		if x.Cmp(bn256.P) >= 0 || y.Cmp(bn256.P) >= 0 {
-			return nil, errInvalidCurvePoint
+	for i := 0; i < len(input); i += 192 {
+		c, err := newCurvePoint(input[i : i+64])
+		if err != nil {
+			return nil, err
 		}
-
-		g2, onCurve := new(bn256.G2).Unmarshal(in[i+64 : i+192])
-		if !onCurve {
-			return nil, errNotOnCurve
-		}
-		x2, y2, _, _ := g2.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
+		t, err := newTwistPoint(input[i+64 : i+192])
+		if err != nil {
+			return nil, err
 		}
-
-		g1s = append(g1s, g1)
-		g2s = append(g2s, g2)
+		cs = append(cs, c)
+		ts = append(ts, t)
 	}
-
-	isOne := bn256.PairingCheck(g1s, g2s)
-	if isOne {
+	// Execute the pairing checks and return the results
+	ok := bn256.PairingCheck(cs, ts)
+	if ok {
 		return true32Byte, nil
 	}
-
-	return fals32Byte, nil
+	return false32Byte, nil
 }

core/vm/contracts_test.go

@@ -1,17 +1,100 @@
 package vm
 
 import (
+	"bytes"
+	"math"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
 )
 
-const input = ""
+// Tests the sample inputs from the ModExp EIP 198.
+func TestPrecompiledModExp(t *testing.T) {
+	bigModExp := &bigModExp{}
 
-func TestPairing(t *testing.T) {
-	pairing := &pairing{}
+	for i, tt := range []struct {
+		input  string
+		gas    uint64
+		output string
+	}{
+		{"00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000002003fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2efffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f", 2611, "0000000000000000000000000000000000000000000000000000000000000001"},
+		{"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000020fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2efffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f", 2611, "0000000000000000000000000000000000000000000000000000000000000000"},
+		{"00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000020fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffd", math.MaxUint64, ""},
+		{"00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002003ffff800000000000000000000000000000000000000000000000000000000000000007", 153, "3b01b01ac41f2d6e917c6d6a221ce793802469026d9ab7578fa2e79e4da6aaab"},
+		{"00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002003ffff80", 153, "3b01b01ac41f2d6e917c6d6a221ce793802469026d9ab7578fa2e79e4da6aaab"},
+	} {
+		gas := bigModExp.RequiredGas(common.FromHex(tt.input))
+		if gas != tt.gas {
+			t.Errorf("test %d: required gas mismatch: have %v, want %v", i, gas, tt.gas)
+			continue
+		}
+		if gas == math.MaxUint64 {
+			continue // Out of gas
+		}
+		out, err := bigModExp.Run(common.FromHex(tt.input))
+		if err != nil {
+			t.Errorf("test %d: contract execution failed: %v", i, err)
+			continue
+		}
+		if !bytes.Equal(out, common.FromHex(tt.output)) {
+			t.Errorf("test %d: contract output mismatch: have %x, want %v", i, out, tt.output)
+		}
+	}
+}
+
+// Tests the sample inputs from the elliptic curve addition EIP 213.
+func TestPrecompiledBn256Add(t *testing.T) {
+	bn256Add := &bn256Add{}
+
+	for i, tt := range []struct {
+		input   string
+		failure error
+		output  string
+	}{
+		{"0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", nil, "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{"", nil, "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{"1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111", errNotOnCurve, ""},
+	} {
+		out, err := bn256Add.Run(common.FromHex(tt.input))
+		if err != tt.failure {
+			t.Errorf("test %d: contract execution failure mismatch: have %v, want %v", i, err, tt.failure)
+			continue
+		}
+		if !bytes.Equal(out, common.FromHex(tt.output)) {
+			t.Errorf("test %d: contract output mismatch: have %x, want %v", i, out, tt.output)
+		}
+	}
+}
+
+// Tests the sample inputs from the elliptic curve scalar multiplication EIP 213.
+func TestPrecompiledBn256ScalarMul(t *testing.T) {
+	bn256ScalarMul := &bn256ScalarMul{}
+
+	for i, tt := range []struct {
+		input   string
+		failure error
+		output  string
+	}{
+		{"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000", nil, "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{"", nil, "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},
+		{"111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111110f00000000000000000000000000000000000000000000000000000000000000", errNotOnCurve, ""},
+	} {
+		out, err := bn256ScalarMul.Run(common.FromHex(tt.input))
+		if err != tt.failure {
+			t.Errorf("test %d: contract execution failure mismatch: have %v, want %v", i, err, tt.failure)
+			continue
+		}
+		if !bytes.Equal(out, common.FromHex(tt.output)) {
+			t.Errorf("test %d: contract output mismatch: have %x, want %v", i, out, tt.output)
+		}
+	}
+}
 
-	for i, test := range []struct {
+// Tests the sample inputs from the elliptic curve pairing check EIP 197.
+func TestPrecompiledBn256Pairing(t *testing.T) {
+	bn256Pairing := &bn256Pairing{}
+
+	for i, tt := range []struct {
 		input string
 		valid int
 	}{
@@ -22,14 +105,12 @@ func TestPairing(t *testing.T) {
 		{"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", 1},
 		{"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", 0},
 	} {
-		r, err := pairing.Run(common.FromHex(test.input))
+		out, err := bn256Pairing.Run(common.FromHex(tt.input))
 		if err != nil {
-			t.Error(i, ":", err)
+			t.Errorf("test %d: contrac execution failed: %v", i, err)
 		}
-
-		if int(r[31]) != test.valid {
-			t.Error(i, "expected", test.valid, "but was", r[31])
+		if int(out[31]) != tt.valid {
+			t.Errorf("test %d: contract output mismatch: have %v, want %v", i, out[31], tt.valid)
 		}
 	}
-
 }

core/vm/evm.go

@@ -36,16 +36,14 @@ type (
 // run runs the given contract and takes care of running precompiles with a fallback to the byte code interpreter.
 func run(evm *EVM, snapshot int, contract *Contract, input []byte) ([]byte, error) {
 	if contract.CodeAddr != nil {
-		precompiledContracts := PrecompiledContracts
+		precompiles := PrecompiledContractsHomestead
 		if evm.ChainConfig().IsMetropolis(evm.BlockNumber) {
-			precompiledContracts = PrecompiledContractsMetropolis
+			precompiles = PrecompiledContractsMetropolis
 		}
-
-		if p := precompiledContracts[*contract.CodeAddr]; p != nil {
+		if p := precompiles[*contract.CodeAddr]; p != nil {
 			return RunPrecompiledContract(p, input, contract)
 		}
 	}
-
 	return evm.interpreter.Run(snapshot, contract, input)
 }
 
@@ -147,10 +145,13 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 		snapshot = evm.StateDB.Snapshot()
 	)
 	if !evm.StateDB.Exist(addr) {
-		if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
+		precompiles := PrecompiledContractsHomestead
+		if evm.ChainConfig().IsMetropolis(evm.BlockNumber) {
+			precompiles = PrecompiledContractsMetropolis
+		}
+		if precompiles[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.Sign() == 0 {
 			return nil, gas, nil
 		}
-
 		evm.StateDB.CreateAccount(addr)
 	}
 	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)

core/vm/instructions_test.go

@@ -69,7 +69,7 @@ func precompiledBenchmark(addr, input, expected string, gas uint64, bench *testi
 	contract := NewContract(AccountRef(common.HexToAddress("1337")),
 		nil, new(big.Int), gas)
 
-	p := PrecompiledContracts[common.HexToAddress(addr)]
+	p := PrecompiledContractsMetropolis[common.HexToAddress(addr)]
 	in := common.Hex2Bytes(input)
 	var (
 		res []byte
@@ -94,7 +94,7 @@ func precompiledBenchmark(addr, input, expected string, gas uint64, bench *testi
 	}
 }
 
-func BenchmarkPrecompiledEcdsa(bench *testing.B) {
+func BenchmarkPrecompiledECDSA(bench *testing.B) {
 	var (
 		addr = "01"
 		inp  = "38d18acb67d25c8bb9942764b62f18e17054f66a817bd4295423adf9ed98873e000000000000000000000000000000000000000000000000000000000000001b38d18acb67d25c8bb9942764b62f18e17054f66a817bd4295423adf9ed98873e789d1dd423d25f0772d2748d60f7e4b81bb14d086eba8e8e8efb6dcff8a4ae02"
@@ -103,6 +103,7 @@ func BenchmarkPrecompiledEcdsa(bench *testing.B) {
 	)
 	precompiledBenchmark(addr, inp, exp, gas, bench)
 }
+
 func BenchmarkPrecompiledSha256(bench *testing.B) {
 	var (
 		addr = "02"
@@ -112,6 +113,7 @@ func BenchmarkPrecompiledSha256(bench *testing.B) {
 	)
 	precompiledBenchmark(addr, inp, exp, gas, bench)
 }
+
 func BenchmarkPrecompiledRipeMD(bench *testing.B) {
 	var (
 		addr = "03"
@@ -121,6 +123,7 @@ func BenchmarkPrecompiledRipeMD(bench *testing.B) {
 	)
 	precompiledBenchmark(addr, inp, exp, gas, bench)
 }
+
 func BenchmarkPrecompiledIdentity(bench *testing.B) {
 	var (
 		addr = "04"
@@ -130,131 +133,171 @@ func BenchmarkPrecompiledIdentity(bench *testing.B) {
 	)
 	precompiledBenchmark(addr, inp, exp, gas, bench)
 }
+
+func BenchmarkPrecompiledModExp(bench *testing.B) {
+	var (
+		addr = "05"
+		inp  = "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000002003fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2efffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f"
+		exp  = "0000000000000000000000000000000000000000000000000000000000000001"
+		gas  = uint64(4000000)
+	)
+	precompiledBenchmark(addr, inp, exp, gas, bench)
+}
+
+func BenchmarkPrecompiledBn256Add(bench *testing.B) {
+	var (
+		addr = "06"
+		inp  = "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+		exp  = "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+		gas  = uint64(4000000)
+	)
+	precompiledBenchmark(addr, inp, exp, gas, bench)
+}
+
+func BenchmarkPrecompiledBn256ScalarMul(bench *testing.B) {
+	var (
+		addr = "07"
+		inp  = "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+		exp  = "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+		gas  = uint64(4000000)
+	)
+	precompiledBenchmark(addr, inp, exp, gas, bench)
+}
+
+func BenchmarkPrecompiledBn256Pairing(bench *testing.B) {
+	var (
+		addr = "08"
+		inp  = "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"
+		exp  = "0000000000000000000000000000000000000000000000000000000000000001"
+		gas  = uint64(4000000)
+	)
+	precompiledBenchmark(addr, inp, exp, gas, bench)
+}
+
 func BenchmarkOpAdd(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opAdd, x, y)
-
 }
+
 func BenchmarkOpSub(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSub, x, y)
-
 }
+
 func BenchmarkOpMul(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opMul, x, y)
-
 }
+
 func BenchmarkOpDiv(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opDiv, x, y)
-
 }
+
 func BenchmarkOpSdiv(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSdiv, x, y)
-
 }
+
 func BenchmarkOpMod(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opMod, x, y)
-
 }
+
 func BenchmarkOpSmod(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSmod, x, y)
-
 }
+
 func BenchmarkOpExp(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opExp, x, y)
-
 }
+
 func BenchmarkOpSignExtend(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSignExtend, x, y)
-
 }
+
 func BenchmarkOpLt(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opLt, x, y)
-
 }
+
 func BenchmarkOpGt(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opGt, x, y)
-
 }
+
 func BenchmarkOpSlt(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSlt, x, y)
-
 }
+
 func BenchmarkOpSgt(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opSgt, x, y)
-
 }
+
 func BenchmarkOpEq(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opEq, x, y)
-
 }
+
 func BenchmarkOpAnd(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opAnd, x, y)
-
 }
+
 func BenchmarkOpOr(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opOr, x, y)
-
 }
+
 func BenchmarkOpXor(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opXor, x, y)
-
 }
+
 func BenchmarkOpByte(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opByte, x, y)
-
 }
 
 func BenchmarkOpAddmod(b *testing.B) {
@@ -263,15 +306,14 @@ func BenchmarkOpAddmod(b *testing.B) {
 	z := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opAddmod, x, y, z)
-
 }
+
 func BenchmarkOpMulmod(b *testing.B) {
 	x := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	y := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 	z := "ABCDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff"
 
 	opBenchmark(b, opMulmod, x, y, z)
-
 }
 
 //func BenchmarkOpSha3(b *testing.B) {

params/protocol_params.go

@@ -31,23 +31,16 @@ const (
 	SstoreSetGas          uint64 = 20000 // Once per SLOAD operation.
 	LogDataGas            uint64 = 8     // Per byte in a LOG* operation's data.
 	CallStipend           uint64 = 2300  // Free gas given at beginning of call.
-	EcrecoverGas          uint64 = 3000  //
-	Sha256WordGas         uint64 = 12    //
 
 	Sha3Gas          uint64 = 30    // Once per SHA3 operation.
-	Sha256Gas        uint64 = 60    //
-	IdentityWordGas  uint64 = 3     //
 	Sha3WordGas      uint64 = 6     // Once per word of the SHA3 operation's data.
 	SstoreResetGas   uint64 = 5000  // Once per SSTORE operation if the zeroness changes from zero.
 	SstoreClearGas   uint64 = 5000  // Once per SSTORE operation if the zeroness doesn't change.
 	SstoreRefundGas  uint64 = 15000 // Once per SSTORE operation if the zeroness changes to zero.
 	JumpdestGas      uint64 = 1     // Refunded gas, once per SSTORE operation if the zeroness changes to zero.
-	IdentityGas      uint64 = 15    //
 	EpochDuration    uint64 = 30000 // Duration between proof-of-work epochs.
 	CallGas          uint64 = 40    // Once per CALL operation & message call transaction.
 	CreateDataGas    uint64 = 200   //
-	Ripemd160Gas     uint64 = 600   //
-	Ripemd160WordGas uint64 = 120   //
 	CallCreateDepth  uint64 = 1024  // Maximum depth of call/create stack.
 	ExpGas           uint64 = 10    // Once per EXP instruction
 	LogGas           uint64 = 375   // Per LOG* operation.
@@ -60,7 +53,22 @@ const (
 	MemoryGas        uint64 = 3     // Times the address of the (highest referenced byte in memory + 1). NOTE: referencing happens on read, write and in instructions such as RETURN and CALL.
 	TxDataNonZeroGas uint64 = 68    // Per byte of data attached to a transaction that is not equal to zero. NOTE: Not payable on data of calls between transactions.
 
-	MaxCodeSize = 24576
+	MaxCodeSize = 24576 // Maximum bytecode to permit for a contract
+
+	// Precompiled contract gas prices
+
+	EcrecoverGas            uint64 = 3000   // Elliptic curve sender recovery gas price
+	Sha256BaseGas           uint64 = 60     // Base price for a SHA256 operation
+	Sha256PerWordGas        uint64 = 12     // Per-word price for a SHA256 operation
+	Ripemd160BaseGas        uint64 = 600    // Base price for a RIPEMD160 operation
+	Ripemd160PerWordGas     uint64 = 120    // Per-word price for a RIPEMD160 operation
+	IdentityBaseGas         uint64 = 15     // Base price for a data copy operation
+	IdentityPerWordGas      uint64 = 3      // Per-work price for a data copy operation
+	ModExpQuadCoeffDiv      uint64 = 100    // Divisor for the quadratic particle of the big int modular exponentiation
+	Bn256AddGas             uint64 = 500    // Gas needed for an elliptic curve addition
+	Bn256ScalarMulGas       uint64 = 2000   // Gas needed for an elliptic curve scalar multiplication
+	Bn256PairingBaseGas     uint64 = 100000 // Base price for an elliptic curve pairing check
+	Bn256PairingPerPointGas uint64 = 80000  // Per-point price for an elliptic curve pairing check
 )
 
 var (