add derivationpath encoder

derivationpath/encoder.go

@@ -0,0 +1,36 @@
+package derivationpath
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"strings"
+)
+
+func Encode(rawPath []uint32) string {
+	segments := []string{string(tokenMaster)}
+
+	for _, i := range rawPath {
+		suffix := ""
+
+		if i >= hardenedStart {
+			i = i - hardenedStart
+			suffix = string(tokenHardened)
+		}
+
+		segments = append(segments, fmt.Sprintf("%d%s", i, suffix))
+	}
+
+	return strings.Join(segments, string(tokenSeparator))
+}
+
+func EncodeFromBytes(data []byte) (string, error) {
+	buf := bytes.NewBuffer(data)
+	rawPath := make([]uint32, buf.Len()/4)
+	err := binary.Read(buf, binary.BigEndian, &rawPath)
+	if err != nil {
+		return "", err
+	}
+
+	return Encode(rawPath), nil
+}

derivationpath/encoder_test.go

@@ -0,0 +1,35 @@
+package derivationpath
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEncode(t *testing.T) {
+	scenarios := []struct {
+		path         []uint32
+		expectedPath string
+	}{
+		{
+			path:         []uint32{},
+			expectedPath: "m",
+		},
+		{
+			path:         []uint32{0, 1, 2},
+			expectedPath: "m/0/1/2",
+		},
+		{
+			path:         []uint32{hardenedStart + 10, 1, 2},
+			expectedPath: "m/10'/1/2",
+		},
+	}
+
+	for i, s := range scenarios {
+		t.Run(fmt.Sprintf("scenario %d", i), func(t *testing.T) {
+			path := Encode(s.path)
+			assert.Equal(t, s.expectedPath, path)
+		})
+	}
+}

types/application_status.go

@@ -2,12 +2,10 @@ package types
 
 import (
 	"bytes"
-	"encoding/binary"
 	"errors"
-	"fmt"
-	"strings"
 
 	"github.com/status-im/keycard-go/apdu"
+	"github.com/status-im/keycard-go/derivationpath"
 )
 
 const hardenedStart = 0x80000000 // 2^31
@@ -48,24 +46,13 @@ func ParseApplicationStatus(data []byte) (*ApplicationStatus, error) {
 
 func parseKeyPathStatus(data []byte) (*ApplicationStatus, error) {
 	appStatus := &ApplicationStatus{}
-	buf := bytes.NewBuffer(data)
-	rawPath := make([]uint32, buf.Len()/4)
-	err := binary.Read(buf, binary.BigEndian, &rawPath)
+
+	path, err := derivationpath.EncodeFromBytes(data)
 	if err != nil {
 		return nil, err
 	}
 
-	segments := []string{"m"}
-	for _, i := range rawPath {
-		suffix := ""
-		if i >= hardenedStart {
-			i = i - hardenedStart
-			suffix = "'"
-		}
-		segments = append(segments, fmt.Sprintf("%d%s", i, suffix))
-	}
-
-	appStatus.Path = strings.Join(segments, "/")
+	appStatus.Path = path
 
 	return appStatus, nil
 }