diff --git a/internal/varsig/varsig.go b/internal/varsig/varsig.go
index 5c1fa5b..03acce7 100644
--- a/internal/varsig/varsig.go
+++ b/internal/varsig/varsig.go
@@ -57,8 +57,8 @@ var (
 // library are supported.
 //
 // [go-libp2p/core/crypto]: github.com/libp2p/go-libp2p/core/crypto
-func Decode(header string) (pb.KeyType, error) {
-	keyType, ok := decMap[header]
+func Decode(header []byte) (pb.KeyType, error) {
+	keyType, ok := decMap[string(header)]
 	if !ok {
 		return -1, fmt.Errorf("%w: %s", ErrUnknownHeader, header)
 	}
@@ -73,13 +73,13 @@ func Decode(header string) (pb.KeyType, error) {
 // library are supported.
 //
 // [go-libp2p/core/crypto]: github.com/libp2p/go-libp2p/core/crypto
-func Encode(keyType pb.KeyType) (string, error) {
+func Encode(keyType pb.KeyType) ([]byte, error) {
 	header, ok := encMap[keyType]
 	if !ok {
-		return "", fmt.Errorf("%w: %s", ErrUnknownKeyType, keyType.String())
+		return nil, fmt.Errorf("%w: %s", ErrUnknownKeyType, keyType.String())
 	}
 
-	return header, nil
+	return []byte(header), nil
 }
 
 func keyTypeToHeader() map[pb.KeyType]string {
diff --git a/internal/varsig/varsig_test.go b/internal/varsig/varsig_test.go
index 4b8277b..21e8292 100644
--- a/internal/varsig/varsig_test.go
+++ b/internal/varsig/varsig_test.go
@@ -14,13 +14,13 @@ func TestDecode(t *testing.T) {
 	t.Parallel()
 
 	notAHeader := base64.RawStdEncoding.EncodeToString([]byte("not a header"))
-	keyType, err := varsig.Decode(notAHeader)
+	keyType, err := varsig.Decode([]byte(notAHeader))
 	assert.Equal(t, pb.KeyType(-1), keyType)
 	assert.ErrorIs(t, err, varsig.ErrUnknownHeader)
 }
 
 func ExampleDecode() {
-	keyType, _ := varsig.Decode("NIUkEoACcQ")
+	keyType, _ := varsig.Decode([]byte("NIUkEoACcQ"))
 	fmt.Println(keyType.String())
 	// Output:
 	// RSA
@@ -30,13 +30,13 @@ func TestEncode(t *testing.T) {
 	t.Parallel()
 
 	header, err := varsig.Encode(pb.KeyType(99))
-	assert.Empty(t, header)
+	assert.Nil(t, header)
 	assert.ErrorIs(t, err, varsig.ErrUnknownKeyType)
 }
 
 func ExampleEncode() {
 	header, _ := varsig.Encode(pb.KeyType_RSA)
-	fmt.Println(header)
+	fmt.Println(string(header))
 
 	// Output:
 	// NIUkEoACcQ