[Gateway] Use personal_sign signatures everywhere (EIP-191) (#10201)

Co-authored-by: Morgan Kuphal <87319522+KuphJr@users.noreply.github.com>

core/services/gateway/common/utils.go

@@ -4,8 +4,9 @@ import (
 	"crypto/ecdsa"
 	"encoding/binary"
 
-	"github.com/ethereum/go-ethereum/crypto"
 	"golang.org/x/exp/slices"
+
+	"github.com/smartcontractkit/chainlink/v2/core/utils"
 )
 
 func Uint32ToBytes(val uint32) []byte {
@@ -30,16 +31,22 @@ func AlignedBytesToString(data []byte) string {
 	return string(data[:idx])
 }
 
+func flatten(data ...[]byte) []byte {
+	var result []byte
+	for _, d := range data {
+		result = append(result, d...)
+	}
+	return result
+}
+
 func SignData(privateKey *ecdsa.PrivateKey, data ...[]byte) ([]byte, error) {
-	hash := crypto.Keccak256Hash(data...)
-	return crypto.Sign(hash.Bytes(), privateKey)
+	return utils.GenerateEthSignature(privateKey, flatten(data...))
 }
 
 func ExtractSigner(signature []byte, data ...[]byte) (signerAddress []byte, err error) {
-	hash := crypto.Keccak256Hash(data...)
-	ecdsaPubKey, err := crypto.SigToPub(hash.Bytes(), signature)
+	addr, err := utils.GetSignersEthAddress(flatten(data...), signature)
 	if err != nil {
 		return nil, err
 	}
-	return crypto.PubkeyToAddress(*ecdsaPubKey).Bytes(), nil
+	return addr.Bytes(), nil
 }