python bindings examples

* Added a key import variant which accesses the SKS keyservers in a
  RESTful fashion and then imports or attempts to import the response.

lang/python/examples/howto/import-keys.py

@@ -0,0 +1,73 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+from __future__ import absolute_import, division, unicode_literals
+
+# Copyright (C) 2018 Ben McGinnes <ben@gnupg.org>
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU General Public License and the GNU
+# Lesser General Public Licensefor more details.
+#
+# You should have received a copy of the GNU General Public License and the GNU
+# Lesser General Public along with this program; if not, see
+# <http://www.gnu.org/licenses/>.
+
+import gpg
+import os.path
+import requests
+
+print("""
+This script imports one or more public keys from the SKS keyservers.
+""")
+
+import gpg
+import requests
+
+c = gpg.Context()
+url = "https://sks-keyservers.net/pks/lookup"
+pattern = input("Enter the pattern to search for key or user IDs: ")
+payload = { "op": "get", "search": pattern }
+
+r = requests.get(url, verify=True, params=payload)
+result = c.key_import(r.content)
+
+if result is not None and hasattr(result, "considered") is False:
+    print(result)
+elif result is not None and hasattr(result, "considered") is True:
+    num_keys = len(result.imports)
+    new_revs = result.new_revocations
+    new_sigs = result.new_signatures
+    new_subs = result.new_sub_keys
+    new_uids = result.new_user_ids
+    new_scrt = result.secret_imported
+    nochange = result.unchanged
+    print("""
+The total number of keys considered for import was:  {0}
+
+   Number of keys revoked:  {1}
+ Number of new signatures:  {2}
+    Number of new subkeys:  {3}
+   Number of new user IDs:  {4}
+Number of new secret keys:  {5}
+ Number of unchanged keys:  {6}
+
+The key IDs for all considered keys were:
+""".format(num_keys, new_revs, new_sigs, new_subs, new_uids, new_scrt,
+           nochange))
+    for i in range(num_keys):
+        print(result.imports[i].fpr)
+    print("")
+else:
+    pass