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+ndnsec-set-default
+==================
+
+``ndnsec-set-default`` is a tool to change the default security settings.
+
+Usage
+-----
+
+::
+
+    $ ndnsec-set-default [-h] [-k|c] name
+
+Description
+-----------
+
+By default, ``ndnsec-set-default`` takes ``name`` as an identity name and sets the identity as the
+system default identity.
+
+Options
+-------
+
+``-k``
+  Set default key. ``name`` should be a key name, ``ndnsec-set-default`` can infer the corresponding
+  identity and set the key as the identity's default key.
+
+``-c``
+  Set default certificate. ``name`` should be a certificate name, ``ndnsec-set-default`` can
+  infer the corresponding key name and set the certificate as the key's default certificate.
+
+Examples
+--------
+
+Set a key's default certificate:
+
+::
+
+    $ ndnsec-set-default -c /ndn/test/KEY/alice/ksk-1394129695025/ID-CERT/%FD%01D%98%9A%F2%3F
+
+Set an identity's default key:
+
+::
+
+    $ ndnsec-set-default -k /ndn/test/alice/ksk-1394129695025
+
+Set system default identity:
+
+::
+
+    $ ndnsec-set-default /ndn/test/alice