diff --git a/examples/graphql/graphql.go b/examples/graphql/graphql.go
index 6cf75a8..ad3c8f8 100644
--- a/examples/graphql/graphql.go
+++ b/examples/graphql/graphql.go
@@ -17,7 +17,7 @@ func main() {
 
 	// Create a client
 	buxClient, err := buxclient.New(
-		buxclient.WithXPriv(keys.XPub().String()),
+		buxclient.WithXPriv(keys.XPriv()),
 		buxclient.WithGraphQL("localhost:3001"),
 		buxclient.WithDebugging(true),
 		buxclient.WithSignRequest(true),
diff --git a/examples/http/http.go b/examples/http/http.go
index e5159d0..c4e988c 100644
--- a/examples/http/http.go
+++ b/examples/http/http.go
@@ -17,7 +17,7 @@ func main() {
 
 	// Create a client
 	buxClient, err := buxclient.New(
-		buxclient.WithXPriv(keys.String()),
+		buxclient.WithXPriv(keys.XPriv()),
 		buxclient.WithHTTP("localhost:3001"),
 		buxclient.WithDebugging(true),
 		buxclient.WithSignRequest(true),
diff --git a/examples/keys/keys.go b/examples/keys/keys.go
index 132e4c7..23ac492 100644
--- a/examples/keys/keys.go
+++ b/examples/keys/keys.go
@@ -13,7 +13,7 @@ func main() {
 	}
 
 	fmt.Println("<-- Generate method")
-	fmt.Println("XPriv: ", keys.String())
+	fmt.Println("XPriv: ", keys.XPriv())
 	fmt.Println("XPub: ", keys.XPub().String())
 	fmt.Println("Mnemonic: ", keys.Mnemonic())
 
@@ -24,18 +24,18 @@ func main() {
 	}
 
 	fmt.Println("<-- FromMnemonic method")
-	fmt.Println("XPriv: ", xpriv3.String())
+	fmt.Println("XPriv: ", xpriv3.XPriv())
 	fmt.Println("XPub: ", xpriv3.XPub().String())
 	fmt.Println("Mnemonic: ", xpriv3.Mnemonic())
 
 	//Generate keys from string
-	xpriv2, err := xpriv.FromString(keys.String())
+	xpriv2, err := xpriv.FromString(keys.XPriv())
 	if err != nil {
 		panic(err)
 	}
 
 	fmt.Println("<-- FromString method")
-	fmt.Println("XPriv: ", xpriv2.String())
+	fmt.Println("XPriv: ", xpriv2.XPriv())
 	fmt.Println("XPub: ", xpriv2.XPub().String())
 	fmt.Println("Can not get mnemonic from keys generated from string")
 }
diff --git a/examples/new_paymail/new_paymail.go b/examples/new_paymail/new_paymail.go
index 8102995..013a992 100644
--- a/examples/new_paymail/new_paymail.go
+++ b/examples/new_paymail/new_paymail.go
@@ -18,7 +18,7 @@ func main() {
 
 	// Create a client
 	buxClient, err := buxclient.New(
-		buxclient.WithXPriv(keys.String()),
+		buxclient.WithXPriv(keys.XPriv()),
 		buxclient.WithHTTP("localhost:3001"),
 		buxclient.WithDebugging(true),
 		buxclient.WithSignRequest(true),
diff --git a/examples/register_xpub/register_xpub.go b/examples/register_xpub/register_xpub.go
index 58eb17d..fb667dc 100644
--- a/examples/register_xpub/register_xpub.go
+++ b/examples/register_xpub/register_xpub.go
@@ -18,7 +18,7 @@ func main() {
 
 	// Create a client
 	buxClient, err := buxclient.New(
-		buxclient.WithXPriv(keys.String()),
+		buxclient.WithXPriv(keys.XPriv()),
 		buxclient.WithHTTP("localhost:3001"),
 		buxclient.WithDebugging(true),
 		buxclient.WithSignRequest(true),
diff --git a/xpriv/xpriv.go b/xpriv/xpriv.go
index 396bfbb..046a57b 100644
--- a/xpriv/xpriv.go
+++ b/xpriv/xpriv.go
@@ -22,7 +22,7 @@ type PublicKey struct {
 
 // Key represents basic key methods
 type Key interface {
-	String() string
+	XPriv() string
 	XPub() PubKey
 }
 
@@ -42,8 +42,8 @@ func (k *Keys) XPub() PubKey {
 	return k.xpub
 }
 
-// String return hierarchical deterministic private key
-func (k *Keys) String() string {
+// XPriv return hierarchical deterministic private key
+func (k *Keys) XPriv() string {
 	return k.xpriv
 }