diff --git a/util/validate_signature.go b/util/validate_signature.go
index e27fbeb..fbe8b12 100644
--- a/util/validate_signature.go
+++ b/util/validate_signature.go
@@ -3,6 +3,7 @@ package util
 import (
 	"encoding/hex"
 
+	"github.com/btcsuite/btcd/btcutil/hdkeychain"
 	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
 )
 
@@ -20,3 +21,16 @@ func ValidateSignature(message string, signature string, publicKey string) bool
 
 	return isValid
 }
+
+func GetHexPubKey(ext_pub_key string) (string, error) {
+	xpubKey, err := hdkeychain.NewKeyFromString(ext_pub_key)
+	if err != nil {
+		return "", err
+	}
+	pubKey, err := xpubKey.ECPubKey()
+	if err != nil {
+		return "", err
+	}
+	byte_key := pubKey.SerializeCompressed()
+	return hex.EncodeToString(byte_key), nil
+}
diff --git a/x/asset/keeper/msg_server_notarize_asset.go b/x/asset/keeper/msg_server_notarize_asset.go
index 3f2ed10..e089b73 100644
--- a/x/asset/keeper/msg_server_notarize_asset.go
+++ b/x/asset/keeper/msg_server_notarize_asset.go
@@ -18,8 +18,11 @@ func (k msgServer) NotarizeAsset(goCtx context.Context, msg *types.MsgNotarizeAs
 	if !found {
 		return nil, errors.New("machine not found")
 	}
-
-	valid := util.ValidateSignature(msg.Hash, msg.Signature, msg.PubKey)
+	hex_pub_key, err := util.GetHexPubKey(msg.PubKey)
+	if err != nil {
+		return nil, errors.New("could not convert xpub key to hex pub key")
+	}
+	valid := util.ValidateSignature(msg.Hash, msg.Signature, hex_pub_key)
 	if !valid {
 		return nil, errors.New("invalid signature")
 	}
@@ -34,3 +37,7 @@ func (k msgServer) NotarizeAsset(goCtx context.Context, msg *types.MsgNotarizeAs
 
 	return &types.MsgNotarizeAssetResponse{}, nil
 }
+
+func getHexPubKey(s string) {
+	panic("unimplemented")
+}