fix verifyingContract to be a valid evm hex address (using cosmos a…

…s hex address) (#9)

ethereum/eip712/domain.go

@@ -16,19 +16,22 @@
 package eip712
 
 import (
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/signer/core/apitypes"
 )
 
 // createEIP712Domain creates the typed data domain for the given chainID.
 func createEIP712Domain(chainID uint64) apitypes.TypedDataDomain {
+	contractStr := "cosmos"
+	contractAddr := common.BytesToAddress([]byte(contractStr))
 	domain := apitypes.TypedDataDomain{
 		Name:              "Carbon",
 		Version:           "1.0.0",
 		ChainId:           math.NewHexOrDecimal256(int64(chainID)),
-		VerifyingContract: "cosmos",
+		VerifyingContract: contractAddr.Hex(),
 		Salt:              "1",
 	}
-
+	
 	return domain
 }