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eth_signatures.go
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/
eth_signatures.go
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package utils
import (
"crypto/ecdsa"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/pkg/errors"
)
const EthSignedMessagePrefix = "\x19Ethereum Signed Message:\n"
func GetSignersEthAddress(msg []byte, sig []byte) (recoveredAddr common.Address, err error) {
if len(sig) != 65 {
return recoveredAddr, errors.New("invalid signature: signature length must be 65 bytes")
}
// Adjust the V component of the signature in case it uses 27 or 28 instead of 0 or 1
if sig[64] == 27 || sig[64] == 28 {
sig[64] -= 27
}
if sig[64] != 0 && sig[64] != 1 {
return recoveredAddr, errors.New("invalid signature: invalid V component")
}
prefixedMsg := fmt.Sprintf("%s%d%s", EthSignedMessagePrefix, len(msg), msg)
hash := crypto.Keccak256Hash([]byte(prefixedMsg))
sigPublicKey, err := crypto.SigToPub(hash[:], sig)
if err != nil {
return recoveredAddr, err
}
recoveredAddr = crypto.PubkeyToAddress(*sigPublicKey)
return recoveredAddr, nil
}
func GenerateEthPrefixedMsgHash(msg []byte) (hash common.Hash) {
prefixedMsg := fmt.Sprintf("%s%d%s", EthSignedMessagePrefix, len(msg), msg)
return crypto.Keccak256Hash([]byte(prefixedMsg))
}
func GenerateEthSignature(privateKey *ecdsa.PrivateKey, msg []byte) (signature []byte, err error) {
hash := GenerateEthPrefixedMsgHash(msg)
return crypto.Sign(hash[:], privateKey)
}