script: temporary homedir creation

* Script to create a temporary gnupg homedir in the user's directory
  for testing or scripting purposes.
* Creates a hidden directory on POSIX systems with the correct
  permissions (700).
* Creates a gpg.conf in that directory containing the same
  configuration options as used in the "Danger Mouse" example in the
  HOWTO with the correct permissions (600).

lang/python/examples/howto/temp-homedir-config.py

@@ -0,0 +1,119 @@
+#!/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 os
+import os.path
+import sys
+
+intro = """
+This script creates a temporary directory to use as a homedir for
+testing key generation tasks with the correct permissions, along
+with a gpg.conf file containing the same configuration options
+listed in the HOWTO.
+
+You may wish to change the order of the cipher preferences or
+remove those not relevant to your installation.  These
+configuration parameters assume that all ciphers and digests are
+installed and available rather than limiting to the default
+ciphers and digests.
+
+The script prompts for a directory name to be installed as a hidden
+directory in the user's home directory on POSIX systems.  So if you
+enter "gnupg-temp" on a Linux, BSD or OS X system, it will create
+"~/.gnupg-temp" (you do not need to enter the leading dot).
+
+This script has not been tested on Windows systems and may have
+unpredictable results.  That said, it will not delete or copy over
+existing data.
+
+If the directory already exists, the script will terminate with a
+message telling you to specify a new directory name.  There is no
+default directory name.  
+"""
+
+gpgconf = """# gpg.conf settings for key generation:
+expert
+allow-freeform-uid
+allow-secret-key-import
+trust-model tofu+pgp
+tofu-default-policy unknown
+enable-large-rsa
+enable-dsa2
+cert-digest-algo SHA512
+default-preference-list TWOFISH CAMELLIA256 AES256 CAMELLIA192 AES192 CAMELLIA128 AES BLOWFISH IDEA CAST5 3DES SHA512 SHA384 SHA256 SHA224 RIPEMD160 SHA1 ZLIB BZIP2 ZIP Uncompressed
+personal-cipher-preferences TWOFISH CAMELLIA256 AES256 CAMELLIA192 AES192 CAMELLIA128 AES BLOWFISH IDEA CAST5 3DES
+personal-digest-preferences SHA512 SHA384 SHA256 SHA224 RIPEMD160 SHA1
+personal-compress-preferences ZLIB BZIP2 ZIP Uncompressed
+"""
+
+if len(sys.argv) == 1:
+    print(intro)
+    new_homedir = input("Enter the temporary gnupg homedir name: ")
+elif len(sys.argv) == 2:
+    new_homedir = sys.argv[1]
+else:
+    new_homedir = " ".join(sys.argv[1:])
+
+userdir = os.path.expanduser("~")
+
+if new_homedir.startswith("~"):
+    new_homdir.replace("~", "")
+else:
+    pass
+
+if new_homedir.startswith("/"):
+    new_homdir.replace("/", "")
+else:
+    pass
+
+if new_homedir.startswith("."):
+    new_homdir.replace(".", "_")
+else:
+    pass
+
+if new_homedir.count(" ") > 0:
+    new_homedir.replace(" ", "_")
+else:
+    pass
+
+nh = "{0}/.{1}".format(userdir, new_homedir)
+
+if os.path.exists(nh) is True:
+    print("The {0} directory already exists.".format(nh))
+else:
+    print("Creating the {0} directory.".format(nh))
+    os.mkdir(nh)
+    os.chmod(nh, 0o700)
+    with open("{0}/{1}".format(nh, "gpg.conf"), "w") as f:
+        f.write(gpgconf)
+    os.chmod("{0}/{1}".format(nh, "gpg.conf"), 0o600)
+    print("""You may now use the {0} directory as an alternative GPG homedir:
+
+gpg --homedir {0}
+gpg --homedir --full-gen-key
+
+Or with GPGME scripts, including the GPGME Python bindings.
+""")