aboutsummaryrefslogblamecommitdiff
path: root/core/vm/contracts.go
blob: 9827bac2abcf114347e4089413c05bc1ad975f54 (plain) (tree)
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
























                                                                                  







                                                         














































                                                                                          






















                                                                               
                                                                                  







                                                                                                                                   
         


                                       























                                                                                      




                                                                                     
                                                    
                                                        

























































                                                                                            
                                 



































































































































































































































































































                                                                                                                           
                                                                       



































                                                                                            








































































































































































































































































































































































































































                                                                                                                                                                                                                                                        
// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"crypto/sha256"
	"encoding/binary"
	"errors"
	"math/big"

	"github.com/ava-labs/coreth/params"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/math"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/crypto/blake2b"
	"github.com/ethereum/go-ethereum/crypto/bls12381"
	"github.com/ethereum/go-ethereum/crypto/bn256"

	//lint:ignore SA1019 Needed for precompile
	"golang.org/x/crypto/ripemd160"
)

// PrecompiledContract is the basic interface for native Go contracts. The implementation
// requires a deterministic gas count based on the input size of the Run method of the
// contract.
type PrecompiledContract interface {
	RequiredGas(input []byte) uint64  // RequiredPrice calculates the contract gas use
	Run(input []byte) ([]byte, error) // Run runs the precompiled contract
}

// PrecompiledContractsHomestead contains the default set of pre-compiled Ethereum
// contracts used in the Frontier and Homestead releases.
var PrecompiledContractsHomestead = map[common.Address]PrecompiledContract{
	common.BytesToAddress([]byte{1}): &ecrecover{},
	common.BytesToAddress([]byte{2}): &sha256hash{},
	common.BytesToAddress([]byte{3}): &ripemd160hash{},
	common.BytesToAddress([]byte{4}): &dataCopy{},
}

// PrecompiledContractsByzantium contains the default set of pre-compiled Ethereum
// contracts used in the Byzantium release.
var PrecompiledContractsByzantium = map[common.Address]PrecompiledContract{
	common.BytesToAddress([]byte{1}): &ecrecover{},
	common.BytesToAddress([]byte{2}): &sha256hash{},
	common.BytesToAddress([]byte{3}): &ripemd160hash{},
	common.BytesToAddress([]byte{4}): &dataCopy{},
	common.BytesToAddress([]byte{5}): &bigModExp{},
	common.BytesToAddress([]byte{6}): &bn256AddByzantium{},
	common.BytesToAddress([]byte{7}): &bn256ScalarMulByzantium{},
	common.BytesToAddress([]byte{8}): &bn256PairingByzantium{},
}

// PrecompiledContractsIstanbul contains the default set of pre-compiled Ethereum
// contracts used in the Istanbul release.
var PrecompiledContractsIstanbul = map[common.Address]PrecompiledContract{
	common.BytesToAddress([]byte{1}): &ecrecover{},
	common.BytesToAddress([]byte{2}): &sha256hash{},
	common.BytesToAddress([]byte{3}): &ripemd160hash{},
	common.BytesToAddress([]byte{4}): &dataCopy{},
	common.BytesToAddress([]byte{5}): &bigModExp{},
	common.BytesToAddress([]byte{6}): &bn256AddIstanbul{},
	common.BytesToAddress([]byte{7}): &bn256ScalarMulIstanbul{},
	common.BytesToAddress([]byte{8}): &bn256PairingIstanbul{},
	common.BytesToAddress([]byte{9}): &blake2F{},
}

// PrecompiledContractsYoloV1 contains the default set of pre-compiled Ethereum
// contracts used in the Yolo v1 test release.
var PrecompiledContractsYoloV1 = map[common.Address]PrecompiledContract{
	common.BytesToAddress([]byte{1}):  &ecrecover{},
	common.BytesToAddress([]byte{2}):  &sha256hash{},
	common.BytesToAddress([]byte{3}):  &ripemd160hash{},
	common.BytesToAddress([]byte{4}):  &dataCopy{},
	common.BytesToAddress([]byte{5}):  &bigModExp{},
	common.BytesToAddress([]byte{6}):  &bn256AddIstanbul{},
	common.BytesToAddress([]byte{7}):  &bn256ScalarMulIstanbul{},
	common.BytesToAddress([]byte{8}):  &bn256PairingIstanbul{},
	common.BytesToAddress([]byte{9}):  &blake2F{},
	common.BytesToAddress([]byte{10}): &bls12381G1Add{},
	common.BytesToAddress([]byte{11}): &bls12381G1Mul{},
	common.BytesToAddress([]byte{12}): &bls12381G1MultiExp{},
	common.BytesToAddress([]byte{13}): &bls12381G2Add{},
	common.BytesToAddress([]byte{14}): &bls12381G2Mul{},
	common.BytesToAddress([]byte{15}): &bls12381G2MultiExp{},
	common.BytesToAddress([]byte{16}): &bls12381Pairing{},
	common.BytesToAddress([]byte{17}): &bls12381MapG1{},
	common.BytesToAddress([]byte{18}): &bls12381MapG2{},
}

// RunPrecompiledContract runs and evaluates the output of a precompiled contract.
// It returns
// - the returned bytes,
// - the _remaining_ gas,
// - any error that occurred
func RunPrecompiledContract(p PrecompiledContract, input []byte, suppliedGas uint64) (ret []byte, remainingGas uint64, err error) {
	gasCost := p.RequiredGas(input)
	if suppliedGas < gasCost {
		return nil, 0, ErrOutOfGas
	}
	suppliedGas -= gasCost
	output, err := p.Run(input)
	return output, suppliedGas, err
}

// ECRECOVER implemented as a native contract.
type ecrecover struct{}

func (c *ecrecover) RequiredGas(input []byte) uint64 {
	return params.EcrecoverGas
}

func (c *ecrecover) Run(input []byte) ([]byte, error) {
	const ecRecoverInputLength = 128

	input = common.RightPadBytes(input, ecRecoverInputLength)
	// "input" is (hash, v, r, s), each 32 bytes
	// but for ecrecover we want (r, s, v)

	r := new(big.Int).SetBytes(input[64:96])
	s := new(big.Int).SetBytes(input[96:128])
	v := input[63] - 27

	// tighter sig s values input homestead only apply to tx sigs
	if !allZero(input[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
		return nil, nil
	}
	// We must make sure not to modify the 'input', so placing the 'v' along with
	// the signature needs to be done on a new allocation
	sig := make([]byte, 65)
	copy(sig, input[64:128])
	sig[64] = v
	// v needs to be at the end for libsecp256k1
	pubKey, err := crypto.Ecrecover(input[:32], sig)
	// make sure the public key is a valid one
	if err != nil {
		return nil, nil
	}

	// the first byte of pubkey is bitcoin heritage
	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
}

// SHA256 implemented as a native contract.
type sha256hash struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *sha256hash) RequiredGas(input []byte) uint64 {
	return uint64(len(input)+31)/32*params.Sha256PerWordGas + params.Sha256BaseGas
}
func (c *sha256hash) Run(input []byte) ([]byte, error) {
	h := sha256.Sum256(input)
	return h[:], nil
}

// RIPEMD160 implemented as a native contract.
type ripemd160hash struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
	return uint64(len(input)+31)/32*params.Ripemd160PerWordGas + params.Ripemd160BaseGas
}
func (c *ripemd160hash) Run(input []byte) ([]byte, error) {
	ripemd := ripemd160.New()
	ripemd.Write(input)
	return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
}

// data copy implemented as a native contract.
type dataCopy struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *dataCopy) RequiredGas(input []byte) uint64 {
	return uint64(len(input)+31)/32*params.IdentityPerWordGas + params.IdentityBaseGas
}
func (c *dataCopy) Run(in []byte) ([]byte, error) {
	return in, nil
}

// bigModExp implements a native big integer exponential modular operation.
type bigModExp struct{}

var (
	big0      = big.NewInt(0)
	big1      = big.NewInt(1)
	big4      = big.NewInt(4)
	big8      = big.NewInt(8)
	big16     = big.NewInt(16)
	big32     = big.NewInt(32)
	big64     = big.NewInt(64)
	big96     = big.NewInt(96)
	big480    = big.NewInt(480)
	big1024   = big.NewInt(1024)
	big3072   = big.NewInt(3072)
	big199680 = big.NewInt(199680)
)

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bigModExp) RequiredGas(input []byte) uint64 {
	var (
		baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
		expLen  = new(big.Int).SetBytes(getData(input, 32, 32))
		modLen  = new(big.Int).SetBytes(getData(input, 64, 32))
	)
	if len(input) > 96 {
		input = input[96:]
	} else {
		input = input[:0]
	}
	// Retrieve the head 32 bytes of exp for the adjusted exponent length
	var expHead *big.Int
	if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
		expHead = new(big.Int)
	} else {
		if expLen.Cmp(big32) > 0 {
			expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
		} else {
			expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
		}
	}
	// Calculate the adjusted exponent length
	var msb int
	if bitlen := expHead.BitLen(); bitlen > 0 {
		msb = bitlen - 1
	}
	adjExpLen := new(big.Int)
	if expLen.Cmp(big32) > 0 {
		adjExpLen.Sub(expLen, big32)
		adjExpLen.Mul(big8, adjExpLen)
	}
	adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))

	// Calculate the gas cost of the operation
	gas := new(big.Int).Set(math.BigMax(modLen, baseLen))
	switch {
	case gas.Cmp(big64) <= 0:
		gas.Mul(gas, gas)
	case gas.Cmp(big1024) <= 0:
		gas = new(big.Int).Add(
			new(big.Int).Div(new(big.Int).Mul(gas, gas), big4),
			new(big.Int).Sub(new(big.Int).Mul(big96, gas), big3072),
		)
	default:
		gas = new(big.Int).Add(
			new(big.Int).Div(new(big.Int).Mul(gas, gas), big16),
			new(big.Int).Sub(new(big.Int).Mul(big480, gas), big199680),
		)
	}
	gas.Mul(gas, math.BigMax(adjExpLen, big1))
	gas.Div(gas, new(big.Int).SetUint64(params.ModExpQuadCoeffDiv))

	if gas.BitLen() > 64 {
		return math.MaxUint64
	}
	return gas.Uint64()
}

func (c *bigModExp) Run(input []byte) ([]byte, error) {
	var (
		baseLen = new(big.Int).SetBytes(getData(input, 0, 32)).Uint64()
		expLen  = new(big.Int).SetBytes(getData(input, 32, 32)).Uint64()
		modLen  = new(big.Int).SetBytes(getData(input, 64, 32)).Uint64()
	)
	if len(input) > 96 {
		input = input[96:]
	} else {
		input = input[:0]
	}
	// Handle a special case when both the base and mod length is zero
	if baseLen == 0 && modLen == 0 {
		return []byte{}, nil
	}
	// Retrieve the operands and execute the exponentiation
	var (
		base = new(big.Int).SetBytes(getData(input, 0, baseLen))
		exp  = new(big.Int).SetBytes(getData(input, baseLen, expLen))
		mod  = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
	)
	if mod.BitLen() == 0 {
		// Modulo 0 is undefined, return zero
		return common.LeftPadBytes([]byte{}, int(modLen)), nil
	}
	return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
}

// newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newCurvePoint(blob []byte) (*bn256.G1, error) {
	p := new(bn256.G1)
	if _, err := p.Unmarshal(blob); err != nil {
		return nil, err
	}
	return p, nil
}

// newTwistPoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newTwistPoint(blob []byte) (*bn256.G2, error) {
	p := new(bn256.G2)
	if _, err := p.Unmarshal(blob); err != nil {
		return nil, err
	}
	return p, nil
}

// runBn256Add implements the Bn256Add precompile, referenced by both
// Byzantium and Istanbul operations.
func runBn256Add(input []byte) ([]byte, error) {
	x, err := newCurvePoint(getData(input, 0, 64))
	if err != nil {
		return nil, err
	}
	y, err := newCurvePoint(getData(input, 64, 64))
	if err != nil {
		return nil, err
	}
	res := new(bn256.G1)
	res.Add(x, y)
	return res.Marshal(), nil
}

// bn256Add implements a native elliptic curve point addition conforming to
// Istanbul consensus rules.
type bn256AddIstanbul struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256AddIstanbul) RequiredGas(input []byte) uint64 {
	return params.Bn256AddGasIstanbul
}

func (c *bn256AddIstanbul) Run(input []byte) ([]byte, error) {
	return runBn256Add(input)
}

// bn256AddByzantium implements a native elliptic curve point addition
// conforming to Byzantium consensus rules.
type bn256AddByzantium struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256AddByzantium) RequiredGas(input []byte) uint64 {
	return params.Bn256AddGasByzantium
}

func (c *bn256AddByzantium) Run(input []byte) ([]byte, error) {
	return runBn256Add(input)
}

// runBn256ScalarMul implements the Bn256ScalarMul precompile, referenced by
// both Byzantium and Istanbul operations.
func runBn256ScalarMul(input []byte) ([]byte, error) {
	p, err := newCurvePoint(getData(input, 0, 64))
	if err != nil {
		return nil, err
	}
	res := new(bn256.G1)
	res.ScalarMult(p, new(big.Int).SetBytes(getData(input, 64, 32)))
	return res.Marshal(), nil
}

// bn256ScalarMulIstanbul implements a native elliptic curve scalar
// multiplication conforming to Istanbul consensus rules.
type bn256ScalarMulIstanbul struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256ScalarMulIstanbul) RequiredGas(input []byte) uint64 {
	return params.Bn256ScalarMulGasIstanbul
}

func (c *bn256ScalarMulIstanbul) Run(input []byte) ([]byte, error) {
	return runBn256ScalarMul(input)
}

// bn256ScalarMulByzantium implements a native elliptic curve scalar
// multiplication conforming to Byzantium consensus rules.
type bn256ScalarMulByzantium struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256ScalarMulByzantium) RequiredGas(input []byte) uint64 {
	return params.Bn256ScalarMulGasByzantium
}

func (c *bn256ScalarMulByzantium) Run(input []byte) ([]byte, error) {
	return runBn256ScalarMul(input)
}

var (
	// true32Byte is returned if the bn256 pairing check succeeds.
	true32Byte = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}

	// false32Byte is returned if the bn256 pairing check fails.
	false32Byte = make([]byte, 32)

	// errBadPairingInput is returned if the bn256 pairing input is invalid.
	errBadPairingInput = errors.New("bad elliptic curve pairing size")
)

// runBn256Pairing implements the Bn256Pairing precompile, referenced by both
// Byzantium and Istanbul operations.
func runBn256Pairing(input []byte) ([]byte, error) {
	// Handle some corner cases cheaply
	if len(input)%192 > 0 {
		return nil, errBadPairingInput
	}
	// Convert the input into a set of coordinates
	var (
		cs []*bn256.G1
		ts []*bn256.G2
	)
	for i := 0; i < len(input); i += 192 {
		c, err := newCurvePoint(input[i : i+64])
		if err != nil {
			return nil, err
		}
		t, err := newTwistPoint(input[i+64 : i+192])
		if err != nil {
			return nil, err
		}
		cs = append(cs, c)
		ts = append(ts, t)
	}
	// Execute the pairing checks and return the results
	if bn256.PairingCheck(cs, ts) {
		return true32Byte, nil
	}
	return false32Byte, nil
}

// bn256PairingIstanbul implements a pairing pre-compile for the bn256 curve
// conforming to Istanbul consensus rules.
type bn256PairingIstanbul struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256PairingIstanbul) RequiredGas(input []byte) uint64 {
	return params.Bn256PairingBaseGasIstanbul + uint64(len(input)/192)*params.Bn256PairingPerPointGasIstanbul
}

func (c *bn256PairingIstanbul) Run(input []byte) ([]byte, error) {
	return runBn256Pairing(input)
}

// bn256PairingByzantium implements a pairing pre-compile for the bn256 curve
// conforming to Byzantium consensus rules.
type bn256PairingByzantium struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256PairingByzantium) RequiredGas(input []byte) uint64 {
	return params.Bn256PairingBaseGasByzantium + uint64(len(input)/192)*params.Bn256PairingPerPointGasByzantium
}

func (c *bn256PairingByzantium) Run(input []byte) ([]byte, error) {
	return runBn256Pairing(input)
}

type blake2F struct{}

func (c *blake2F) RequiredGas(input []byte) uint64 {
	// If the input is malformed, we can't calculate the gas, return 0 and let the
	// actual call choke and fault.
	if len(input) != blake2FInputLength {
		return 0
	}
	return uint64(binary.BigEndian.Uint32(input[0:4]))
}

const (
	blake2FInputLength        = 213
	blake2FFinalBlockBytes    = byte(1)
	blake2FNonFinalBlockBytes = byte(0)
)

var (
	errBlake2FInvalidInputLength = errors.New("invalid input length")
	errBlake2FInvalidFinalFlag   = errors.New("invalid final flag")
)

func (c *blake2F) Run(input []byte) ([]byte, error) {
	// Make sure the input is valid (correct length and final flag)
	if len(input) != blake2FInputLength {
		return nil, errBlake2FInvalidInputLength
	}
	if input[212] != blake2FNonFinalBlockBytes && input[212] != blake2FFinalBlockBytes {
		return nil, errBlake2FInvalidFinalFlag
	}
	// Parse the input into the Blake2b call parameters
	var (
		rounds = binary.BigEndian.Uint32(input[0:4])
		final  = (input[212] == blake2FFinalBlockBytes)

		h [8]uint64
		m [16]uint64
		t [2]uint64
	)
	for i := 0; i < 8; i++ {
		offset := 4 + i*8
		h[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
	}
	for i := 0; i < 16; i++ {
		offset := 68 + i*8
		m[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
	}
	t[0] = binary.LittleEndian.Uint64(input[196:204])
	t[1] = binary.LittleEndian.Uint64(input[204:212])

	// Execute the compression function, extract and return the result
	blake2b.F(&h, m, t, final, rounds)

	output := make([]byte, 64)
	for i := 0; i < 8; i++ {
		offset := i * 8
		binary.LittleEndian.PutUint64(output[offset:offset+8], h[i])
	}
	return output, nil
}

var (
	errBLS12381InvalidInputLength          = errors.New("invalid input length")
	errBLS12381InvalidFieldElementTopBytes = errors.New("invalid field element top bytes")
	errBLS12381G1PointSubgroup             = errors.New("g1 point is not on correct subgroup")
	errBLS12381G2PointSubgroup             = errors.New("g2 point is not on correct subgroup")
)

// bls12381G1Add implements EIP-2537 G1Add precompile.
type bls12381G1Add struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1Add) RequiredGas(input []byte) uint64 {
	return params.Bls12381G1AddGas
}

func (c *bls12381G1Add) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G1Add precompile.
	// > G1 addition call expects `256` bytes as an input that is interpreted as byte concatenation of two G1 points (`128` bytes each).
	// > Output is an encoding of addition operation result - single G1 point (`128` bytes).
	if len(input) != 256 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	var p0, p1 *bls12381.PointG1

	// Initialize G1
	g := bls12381.NewG1()

	// Decode G1 point p_0
	if p0, err = g.DecodePoint(input[:128]); err != nil {
		return nil, err
	}
	// Decode G1 point p_1
	if p1, err = g.DecodePoint(input[128:]); err != nil {
		return nil, err
	}

	// Compute r = p_0 + p_1
	r := g.New()
	g.Add(r, p0, p1)

	// Encode the G1 point result into 128 bytes
	return g.EncodePoint(r), nil
}

// bls12381G1Mul implements EIP-2537 G1Mul precompile.
type bls12381G1Mul struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1Mul) RequiredGas(input []byte) uint64 {
	return params.Bls12381G1MulGas
}

func (c *bls12381G1Mul) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G1Mul precompile.
	// > G1 multiplication call expects `160` bytes as an input that is interpreted as byte concatenation of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32` bytes).
	// > Output is an encoding of multiplication operation result - single G1 point (`128` bytes).
	if len(input) != 160 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	var p0 *bls12381.PointG1

	// Initialize G1
	g := bls12381.NewG1()

	// Decode G1 point
	if p0, err = g.DecodePoint(input[:128]); err != nil {
		return nil, err
	}
	// Decode scalar value
	e := new(big.Int).SetBytes(input[128:])

	// Compute r = e * p_0
	r := g.New()
	g.MulScalar(r, p0, e)

	// Encode the G1 point into 128 bytes
	return g.EncodePoint(r), nil
}

// bls12381G1MultiExp implements EIP-2537 G1MultiExp precompile.
type bls12381G1MultiExp struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G1MultiExp) RequiredGas(input []byte) uint64 {
	// Calculate G1 point, scalar value pair length
	k := len(input) / 160
	if k == 0 {
		// Return 0 gas for small input length
		return 0
	}
	// Lookup discount value for G1 point, scalar value pair length
	var discount uint64
	if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen {
		discount = params.Bls12381MultiExpDiscountTable[k-1]
	} else {
		discount = params.Bls12381MultiExpDiscountTable[dLen-1]
	}
	// Calculate gas and return the result
	return (uint64(k) * params.Bls12381G1MulGas * discount) / 1000
}

func (c *bls12381G1MultiExp) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G1MultiExp precompile.
	// G1 multiplication call expects `160*k` bytes as an input that is interpreted as byte concatenation of `k` slices each of them being a byte concatenation of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32` bytes).
	// Output is an encoding of multiexponentiation operation result - single G1 point (`128` bytes).
	k := len(input) / 160
	if len(input) == 0 || len(input)%160 != 0 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	points := make([]*bls12381.PointG1, k)
	scalars := make([]*big.Int, k)

	// Initialize G1
	g := bls12381.NewG1()

	// Decode point scalar pairs
	for i := 0; i < k; i++ {
		off := 160 * i
		t0, t1, t2 := off, off+128, off+160
		// Decode G1 point
		if points[i], err = g.DecodePoint(input[t0:t1]); err != nil {
			return nil, err
		}
		// Decode scalar value
		scalars[i] = new(big.Int).SetBytes(input[t1:t2])
	}

	// Compute r = e_0 * p_0 + e_1 * p_1 + ... + e_(k-1) * p_(k-1)
	r := g.New()
	g.MultiExp(r, points, scalars)

	// Encode the G1 point to 128 bytes
	return g.EncodePoint(r), nil
}

// bls12381G2Add implements EIP-2537 G2Add precompile.
type bls12381G2Add struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2Add) RequiredGas(input []byte) uint64 {
	return params.Bls12381G2AddGas
}

func (c *bls12381G2Add) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G2Add precompile.
	// > G2 addition call expects `512` bytes as an input that is interpreted as byte concatenation of two G2 points (`256` bytes each).
	// > Output is an encoding of addition operation result - single G2 point (`256` bytes).
	if len(input) != 512 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	var p0, p1 *bls12381.PointG2

	// Initialize G2
	g := bls12381.NewG2()
	r := g.New()

	// Decode G2 point p_0
	if p0, err = g.DecodePoint(input[:256]); err != nil {
		return nil, err
	}
	// Decode G2 point p_1
	if p1, err = g.DecodePoint(input[256:]); err != nil {
		return nil, err
	}

	// Compute r = p_0 + p_1
	g.Add(r, p0, p1)

	// Encode the G2 point into 256 bytes
	return g.EncodePoint(r), nil
}

// bls12381G2Mul implements EIP-2537 G2Mul precompile.
type bls12381G2Mul struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2Mul) RequiredGas(input []byte) uint64 {
	return params.Bls12381G2MulGas
}

func (c *bls12381G2Mul) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G2MUL precompile logic.
	// > G2 multiplication call expects `288` bytes as an input that is interpreted as byte concatenation of encoding of G2 point (`256` bytes) and encoding of a scalar value (`32` bytes).
	// > Output is an encoding of multiplication operation result - single G2 point (`256` bytes).
	if len(input) != 288 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	var p0 *bls12381.PointG2

	// Initialize G2
	g := bls12381.NewG2()

	// Decode G2 point
	if p0, err = g.DecodePoint(input[:256]); err != nil {
		return nil, err
	}
	// Decode scalar value
	e := new(big.Int).SetBytes(input[256:])

	// Compute r = e * p_0
	r := g.New()
	g.MulScalar(r, p0, e)

	// Encode the G2 point into 256 bytes
	return g.EncodePoint(r), nil
}

// bls12381G2MultiExp implements EIP-2537 G2MultiExp precompile.
type bls12381G2MultiExp struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381G2MultiExp) RequiredGas(input []byte) uint64 {
	// Calculate G2 point, scalar value pair length
	k := len(input) / 288
	if k == 0 {
		// Return 0 gas for small input length
		return 0
	}
	// Lookup discount value for G2 point, scalar value pair length
	var discount uint64
	if dLen := len(params.Bls12381MultiExpDiscountTable); k < dLen {
		discount = params.Bls12381MultiExpDiscountTable[k-1]
	} else {
		discount = params.Bls12381MultiExpDiscountTable[dLen-1]
	}
	// Calculate gas and return the result
	return (uint64(k) * params.Bls12381G2MulGas * discount) / 1000
}

func (c *bls12381G2MultiExp) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 G2MultiExp precompile logic
	// > G2 multiplication call expects `288*k` bytes as an input that is interpreted as byte concatenation of `k` slices each of them being a byte concatenation of encoding of G2 point (`256` bytes) and encoding of a scalar value (`32` bytes).
	// > Output is an encoding of multiexponentiation operation result - single G2 point (`256` bytes).
	k := len(input) / 288
	if len(input) == 0 || len(input)%288 != 0 {
		return nil, errBLS12381InvalidInputLength
	}
	var err error
	points := make([]*bls12381.PointG2, k)
	scalars := make([]*big.Int, k)

	// Initialize G2
	g := bls12381.NewG2()

	// Decode point scalar pairs
	for i := 0; i < k; i++ {
		off := 288 * i
		t0, t1, t2 := off, off+256, off+288
		// Decode G1 point
		if points[i], err = g.DecodePoint(input[t0:t1]); err != nil {
			return nil, err
		}
		// Decode scalar value
		scalars[i] = new(big.Int).SetBytes(input[t1:t2])
	}

	// Compute r = e_0 * p_0 + e_1 * p_1 + ... + e_(k-1) * p_(k-1)
	r := g.New()
	g.MultiExp(r, points, scalars)

	// Encode the G2 point to 256 bytes.
	return g.EncodePoint(r), nil
}

// bls12381Pairing implements EIP-2537 Pairing precompile.
type bls12381Pairing struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381Pairing) RequiredGas(input []byte) uint64 {
	return params.Bls12381PairingBaseGas + uint64(len(input)/384)*params.Bls12381PairingPerPairGas
}

func (c *bls12381Pairing) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 Pairing precompile logic.
	// > Pairing call expects `384*k` bytes as an inputs that is interpreted as byte concatenation of `k` slices. Each slice has the following structure:
	// > - `128` bytes of G1 point encoding
	// > - `256` bytes of G2 point encoding
	// > Output is a `32` bytes where last single byte is `0x01` if pairing result is equal to multiplicative identity in a pairing target field and `0x00` otherwise
	// > (which is equivalent of Big Endian encoding of Solidity values `uint256(1)` and `uin256(0)` respectively).
	k := len(input) / 384
	if len(input) == 0 || len(input)%384 != 0 {
		return nil, errBLS12381InvalidInputLength
	}

	// Initialize BLS12-381 pairing engine
	e := bls12381.NewPairingEngine()
	g1, g2 := e.G1, e.G2

	// Decode pairs
	for i := 0; i < k; i++ {
		off := 384 * i
		t0, t1, t2 := off, off+128, off+384

		// Decode G1 point
		p1, err := g1.DecodePoint(input[t0:t1])
		if err != nil {
			return nil, err
		}
		// Decode G2 point
		p2, err := g2.DecodePoint(input[t1:t2])
		if err != nil {
			return nil, err
		}

		// 'point is on curve' check already done,
		// Here we need to apply subgroup checks.
		if !g1.InCorrectSubgroup(p1) {
			return nil, errBLS12381G1PointSubgroup
		}
		if !g2.InCorrectSubgroup(p2) {
			return nil, errBLS12381G2PointSubgroup
		}

		// Update pairing engine with G1 and G2 ponits
		e.AddPair(p1, p2)
	}
	// Prepare 32 byte output
	out := make([]byte, 32)

	// Compute pairing and set the result
	if e.Check() {
		out[31] = 1
	}
	return out, nil
}

// decodeBLS12381FieldElement decodes BLS12-381 elliptic curve field element.
// Removes top 16 bytes of 64 byte input.
func decodeBLS12381FieldElement(in []byte) ([]byte, error) {
	if len(in) != 64 {
		return nil, errors.New("invalid field element length")
	}
	// check top bytes
	for i := 0; i < 16; i++ {
		if in[i] != byte(0x00) {
			return nil, errBLS12381InvalidFieldElementTopBytes
		}
	}
	out := make([]byte, 48)
	copy(out[:], in[16:])
	return out, nil
}

// bls12381MapG1 implements EIP-2537 MapG1 precompile.
type bls12381MapG1 struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381MapG1) RequiredGas(input []byte) uint64 {
	return params.Bls12381MapG1Gas
}

func (c *bls12381MapG1) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 Map_To_G1 precompile.
	// > Field-to-curve call expects `64` bytes an an input that is interpreted as a an element of the base field.
	// > Output of this call is `128` bytes and is G1 point following respective encoding rules.
	if len(input) != 64 {
		return nil, errBLS12381InvalidInputLength
	}

	// Decode input field element
	fe, err := decodeBLS12381FieldElement(input)
	if err != nil {
		return nil, err
	}

	// Initialize G1
	g := bls12381.NewG1()

	// Compute mapping
	r, err := g.MapToCurve(fe)
	if err != nil {
		return nil, err
	}

	// Encode the G1 point to 128 bytes
	return g.EncodePoint(r), nil
}

// bls12381MapG2 implements EIP-2537 MapG2 precompile.
type bls12381MapG2 struct{}

// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bls12381MapG2) RequiredGas(input []byte) uint64 {
	return params.Bls12381MapG2Gas
}

func (c *bls12381MapG2) Run(input []byte) ([]byte, error) {
	// Implements EIP-2537 Map_FP2_TO_G2 precompile logic.
	// > Field-to-curve call expects `128` bytes an an input that is interpreted as a an element of the quadratic extension field.
	// > Output of this call is `256` bytes and is G2 point following respective encoding rules.
	if len(input) != 128 {
		return nil, errBLS12381InvalidInputLength
	}

	// Decode input field element
	fe := make([]byte, 96)
	c0, err := decodeBLS12381FieldElement(input[:64])
	if err != nil {
		return nil, err
	}
	copy(fe[48:], c0)
	c1, err := decodeBLS12381FieldElement(input[64:])
	if err != nil {
		return nil, err
	}
	copy(fe[:48], c1)

	// Initialize G2
	g := bls12381.NewG2()

	// Compute mapping
	r, err := g.MapToCurve(fe)
	if err != nil {
		return nil, err
	}

	// Encode the G2 point to 256 bytes
	return g.EncodePoint(r), nil
}