diff --git a/pkg/crypto/verifiable.go b/pkg/crypto/verifiable.go
new file mode 100644
index 000000000..6dc643c1d
--- /dev/null
+++ b/pkg/crypto/verifiable.go
@@ -0,0 +1,6 @@
+package crypto
+
+// Verifiable represents an object which can be verified.
+type Verifiable interface {
+	GetSignedPart() []byte
+}