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QGB Use Ecrecover to validate Ethereum signatures #605

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merged 5 commits into from
Aug 17, 2022
Merged

QGB Use Ecrecover to validate Ethereum signatures #605

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382e994
updates ethereum signer implementation
rach-id Aug 10, 2022
ce463c5
update test for correct signature
rach-id Aug 10, 2022
a9de4cd
go.sum
rach-id Aug 10, 2022
47266dc
Update x/qgb/types/ethereum_signer.go
rach-id Aug 12, 2022
17a1463
Update x/qgb/types/ethereum_signer.go
rach-id Aug 12, 2022
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35 changes: 9 additions & 26 deletions x/qgb/types/ethereum_signer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,8 @@ package types
import (
"crypto/ecdsa"

"github.com/ethereum/go-ethereum/common"

sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
)

Expand All @@ -18,40 +17,24 @@ func NewEthereumSignature(hash []byte, privateKey *ecdsa.PrivateKey) ([]byte, er
if privateKey == nil {
return nil, sdkerrors.Wrap(ErrEmpty, "private key")
}
protectedHash := crypto.Keccak256Hash(append([]uint8(signaturePrefix), hash...))
protectedHash := crypto.Keccak256Hash([]uint8(signaturePrefix), hash)
return crypto.Sign(protectedHash.Bytes(), privateKey)
}

func EthAddressFromSignature(hash []byte, signature []byte) (common.Address, error) {
if len(signature) < 65 {
return common.Address{}, sdkerrors.Wrap(ErrInvalid, "signature too short")
}
// To verify signature
// - use crypto.SigToPub to get the public key
// - use crypto.PubkeyToAddress to get the address
// - compare this to the address given.

// for backwards compatibility reasons the V value of an Ethereum sig is presented
// as 27 or 28, internally though it should be a 0-3 value due to changed formats.
// It seems that go-ethereum expects this to be done before sigs actually reach it's
// internal validation functions. In order to comply with this requirement we check
// the sig an dif it's in standard format we correct it. If it's in go-ethereum's expected
// format already we make no changes.
//
// We could attempt to break or otherwise exit early on obviously invalid values for this
// byte, but that's a task best left to go-ethereum
if signature[64] == 27 || signature[64] == 28 {
signature[64] -= 27
Comment on lines -43 to -44
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Out of curiosity, why is this no longer necessary?

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https://twitter.com/alexberegszaszi/status/1534461421454606336?t=6hUf4_GjhEuFBVdj_Kqzew&s=19

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wow so a bunch of smart contracts include this check even though it's unnecessary

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yes. And also in our case we were adding this check while it's not needed.

protectedHash := crypto.Keccak256Hash([]uint8(signaturePrefix), hash)
sigPublicKey, err := crypto.Ecrecover(protectedHash.Bytes(), signature)
if err != nil {
return common.Address{}, sdkerrors.Wrap(err, "ec recover failed")
}

protectedHash := crypto.Keccak256Hash(append([]uint8(signaturePrefix), hash...))

pubkey, err := crypto.SigToPub(protectedHash.Bytes(), signature)
pubKey, err := crypto.UnmarshalPubkey(sigPublicKey)
if err != nil {
return common.Address{}, sdkerrors.Wrap(err, "signature to public key")
return common.Address{}, sdkerrors.Wrap(err, "unmarshalling signature public key failed")
}

addr := crypto.PubkeyToAddress(*pubkey)
addr := crypto.PubkeyToAddress(*pubKey)
return addr, nil
}

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4 changes: 2 additions & 2 deletions x/qgb/types/ethereum_signer_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,8 @@ import (

func TestValsetConfirmSig(t *testing.T) {
const (
correctSig = "e108a7776de6b87183b0690484a74daef44aa6daf907e91abaf7bbfa426ae7706b12e0bd44ef7b0634710d99c2d81087a2f39e075158212343a3b2948ecf33d01c"
invalidSig = "fffff7776de6b87183b0690484a74daef44aa6daf907e91abaf7bbfa426ae7706b12e0bd44ef7b0634710d99c2d81087a2f39e075158212343a3b2948ecf33d01c"
correctSig = "e108a7776de6b87183b0690484a74daef44aa6daf907e91abaf7bbfa426ae7706b12e0bd44ef7b0634710d99c2d81087a2f39e075158212343a3b2948ecf33d001"
invalidSig = "fffff7776de6b87183b0690484a74daef44aa6daf907e91abaf7bbfa426ae7706b12e0bd44ef7b0634710d99c2d81087a2f39e075158212343a3b2948ecf33d001"
ethAddress = "0xc783df8a850f42e7F7e57013759C285caa701eB6"
hash = "88165860d955aee7dc3e83d9d1156a5864b708841965585d206dbef6e9e1a499"
)
Expand Down