added namespace fingerprint

1 files changed, 12 insertions, 0 deletions

diff --git a/types/namespace.go b/types/namespace.go
index 8a2ad17..f221960 100644
--- a/types/namespace.go
+++ b/types/namespace.go
@@ -14,6 +14,8 @@ type NamespaceFormat tls.Enum
 const (
 	NamespaceFormatReserved  NamespaceFormat = 0
 	NamespaceFormatEd25519V1 NamespaceFormat = 1
+
+	NamespaceFingerprintSize = 32
 )
 
 // Namespace references a versioned namespace based on a given format specifier
@@ -50,6 +52,16 @@ func (n Namespace) String() string {
 	}
 }
 
+// Fingerprint returns a fixed-size namespace fingerprint that is unique.
+func (n *Namespace) Fingerprint() (*[NamespaceFingerprintSize]byte, error) {
+	switch n.Format {
+	case NamespaceFormatEd25519V1:
+		return &n.Ed25519V1.Namespace, nil
+	default:
+		return nil, fmt.Errorf("unsupported NamespaceFormat: %v", n.Format)
+	}
+}
+
 // NewNamespaceEd25519V1 returns an new Ed25519V1 namespace based on a
 // verification key.
 func NewNamespaceEd25519V1(vk []byte) (*Namespace, error) {