added interface for new methods

data/interface.go

@@ -314,6 +314,12 @@ type GuardedTransactionHandler interface {
 	GetDataForSigning(encoder Encoder, marshaller Marshaller, hasher Hasher) ([]byte, error)
 }
 
+// RelayedTransactionHandler defines functionality for the relayed transactions
+type RelayedTransactionHandler interface {
+	GetRelayerAddr() []byte
+	GetRelayerSignature() []byte
+}
+
 // LogHandler defines the type for a log resulted from executing a transaction or smart contract call
 type LogHandler interface {
 	// GetAddress returns the address of the sc that was originally called by the user

data/transaction/transaction.go

@@ -102,6 +102,15 @@ func (tx *Transaction) GetDataForSigning(encoder data.Encoder, marshaller data.M
 		ftx.GuardianAddr = guardianAddr
 	}
 
+	if len(tx.RelayerAddr) > 0 {
+		relayerAddr, errRelayer := encoder.Encode(tx.RelayerAddr)
+		if errRelayer != nil {
+			return nil, errRelayer
+		}
+
+		ftx.RelayerAddr = relayerAddr
+	}
+
 	ftxBytes, err := marshaller.Marshal(ftx)
 	if err != nil {
 		return nil, err