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+ndnsec-cert-gen
+===============
+
+``ndnsec-cert-gen`` is a tool to issue an identity certificate.
+
+Usage
+-----
+
+::
+
+    $ ndnsec-cert-gen [-h] [-S timestamp] [-E timestamp] [-N name] [-I info] [-s sign-id] request
+
+Description
+-----------
+
+``ndnsec-cert-gen`` takes signing request as input and issues an identity certificate for the key in
+the signing request. The signing request can be created during ``ndnsec-keygen`` and can be
+re-generated with ``ndnsec-sign-req``.
+
+By default, the default key/certificate will be used to sign the issued certificate.
+
+``request`` could be a path to a file that contains the signing request. If ``request`` is ``-``,
+then signing request will be read from standard input.
+
+The generated certificate will be written to standard output in base64 encoding.
+
+
+Options
+-------
+
+``-S timestamp``
+  Timestamp when the certificate becomes valid. The default value is now.
+
+``-E timestamp``
+  Timestamp when the certificate expires. The default value is one year from now.
+
+``-N name``
+  Name of the certificate owner.
+
+``-I info``
+  Other information about the certificate owner. ``subject-info`` is a list of pairs of OID and
+  corresponding value. For example, "2.5.4.10 'Some Organization' 2.5.4.3 'http://home.page/'".
+
+``-s sign-id``
+  Signing identity. The default key/certificate of ``sign-id`` will be used to sign the requested
+  certificate. If this option is not specified, the system default identity will be used.
+
+Examples
+--------
+
+::
+
+    $ ndnsec-cert-gen -S 20140401000000 -E 20150331235959 -N "David"
+    -I "2.5.4.10 'Some Organization'" -s /ndn/test sign_request.cert
+    Bv0C9wc9CANuZG4IBHRlc3QIA0tFWQgFZGF2aWQIEWtzay0xMzk2OTEzMDU4MTk2
+    CAdJRC1DRVJUCAgAAAFFPp2g3hQDGAECFf0BdjCCAXIwIhgPMjAxNDA0MDEwMDAw
+    MDBaGA8yMDE1MDMzMTIzNTk1OVowKDAMBgNVBCkTBURhdmlkMBgGA1UEChMRU29t
+    ZSBPcmdhbml6YXRpb24wggEgMA0GCSqGSIb3DQEBAQUAA4IBDQAwggEIAoIBAQC0
+    urnS2nKcnXnMTESH2XqO+H8c6bCE6mmv+FMQ9hSfZVOHbX4kkiDmkcAAf8NCvwGr
+    kEat0NQIhKHFLFtofC5rXLheAo/UxgFA/9bNwiEjMH/c8EN2YTSMzdCDrK6TwE7B
+    623cLTsa3Bb11+BpzC1oLb3Egedgp+vIf+AFIgNQhvfwzsgsgOBB4iJBwcYegU7w
+    JsO0pjY69WQU2DGjABFef6C2Qh8x0TvtnynRLbWlh928+4ilVUvLuWcV3AbPIKLe
+    eZu13+v01JN6kFzNZDPMFtOFPvJ943IdYu7Q9k93PzhSk0+wFp3cHH21PfWeghWe
+    3zLIER8RTWPIQhWSbxRVAgERFjMbAQEcLgcsCANuZG4IA0tFWQgEdGVzdAgRa3Nr
+    LTEzOTQxMjk2OTQ3ODgIB0lELUNFUlQX/QEABUGcl7U+F8cwMHKckerv+1H2Nvsd
+    OfeqX0+4RzWU+wRx2emMGMZZdHSx8M/i45hb0P5hbNEF99L35/SrSTSzhTZdOriD
+    t/LQOcKBoNXY+iw3EUFM0gvRGU0kaEVBKAHtbYhtoHc48QLEyrsVaMqmrjCmpeF/
+    JOcClhzJfFW3cZ/SlhcTEayF0ntogYLR2cMzIwQhhSj5L/Kl7I7uxNxZhK1DS98n
+    q8oGAxHufEAluPrRpDQfI+jeQ4h/YYKcXPW3Vn7VQAGOqIi6gTlUxrmEbyCDF70E
+    xj5t3wfSUmDa1N+hLRMdEAI+IjRRHDSx2Lhj/QcoPIZPWwKjBz9CBL92og==