Authentication with NDEF message on Desfire containing signed UID via Ed25519

sign_uid.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python2
+
+import sys
+import os
+import axolotl_curve25519 as curve
+
+def signUid(private_key, uid):
+    """
+    Create an Ed25519 signature for UID
+    :param private_key: Binary representation of Ed25519 key
+    :param uid: UID, decoded to binary from hex
+    :return: singature in binary format
+    """
+    random64 = os.urandom(64)
+    signature = curve.calculateSignature(random64, private_key, uid)
+    return signature
+
+if __name__ == "__main__":
+
+    if len(sys.argv) < 3:
+        print >> sys.stderr, "Usage: sign_uid.py uid_hex ed25519_private_key_hex"
+        print >> sys.stderr, "Outputs binary signature, you will probably want to redirect it to a file"
+        sys.exit(1)
+
+    private_key = sys.argv[3].decode("hex")
+    uid_bin = sys.argv[1].decode("hex")
+    sys.stdout.write(signUid(private_key, uid_bin))