Added signature script.

Now it is possible to create the signature files easily using the
command generate-signature-key with the correct arguments.

The command generate-signature-key works without any argument as well.

To check the arguments you must run with the parameter --help/-h.

It'll generate two file, one is a private key and the other is a
X509 certificate file.

Those files must be used by networkcache to play with signature.

The private key is required to sign the message before uploading it to
shadir. And the certification file is required to verify the signature.

slapos/signature.py

+##############################################################################
+#
+# Copyright (c) 2010 ViFiB SARL and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+
+
+import M2Crypto
+import time
+import argparse
+import sys
+
+
+def createPrivateKeyAndCertificateFile(signature_public_file, signature_private_file, **kw):
+  ''' It must create a private key and a certificate file. '''
+  cur_time = M2Crypto.ASN1.ASN1_UTCTIME()
+  cur_time.set_time(int(time.time()) - 60*60*24)
+  expire_time = M2Crypto.ASN1.ASN1_UTCTIME()
+  expire_time.set_time(int(time.time()) + 60 * 60 * 24 * 365)
+
+  cs_rsa = M2Crypto.RSA.gen_key(1024, 65537, lambda: None)
+  cs_pk = M2Crypto.EVP.PKey()
+  cs_pk.assign_rsa(cs_rsa)
+
+  cs_cert = M2Crypto.X509.X509()
+  cs_cert.set_not_before(cur_time)
+  cs_cert.set_not_after(expire_time)
+  cs_cert.set_pubkey(cs_pk)
+
+  cs_name = M2Crypto.X509.X509_Name()
+  cs_name.C = kw.get('country', '')
+  cs_name.SP = kw.get('state_name', '')
+  cs_name.L = kw.get('locality', '')
+  cs_name.O = kw.get('organization_name', '')
+  cs_name.OU = kw.get('organization_unit_name', '')
+  cs_name.CN = kw.get('common_name', '')
+  cs_name.Email = kw.get('common_name', '')
+
+  cs_cert.set_subject(cs_name)
+  cs_cert.set_issuer_name(cs_name)
+  cs_cert.sign(cs_pk, md="sha256")
+
+  # Saving...
+  cs_cert.save_pem(signature_public_file)
+  cs_rsa.save_pem(signature_private_file, None)
+  return cs_cert.as_text()
+
+
+def parseArgument(*args):
+  ''' Parses command line arguments. '''
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--signature-public-file',
+                      default='public.pem',
+                      help='Signature public file.')
+
+  parser.add_argument('--signature-private-file',
+                      default='private.pem',
+                      help='Signature private file.')
+
+  parser.add_argument('-c','--country',
+                      default='XX',
+                      help='Country Name (2 letter code).')
+
+  parser.add_argument('-s', '--state-name',
+                      default='Default Province',
+                      help='State or Province Name (full name).')
+
+  parser.add_argument('-l', '--locality-name',
+                      default='Default City',
+                      help='Locality Name (eg, city).')
+
+  parser.add_argument('-o', '--organization-name',
+                      default='Default Company Ltd',
+                      help='Organization Name (eg, company).')
+
+  parser.add_argument('-ou', '--organization-unit-name',
+                      default='',
+                      help='Organizational Unit Name (eg, section).')
+
+  parser.add_argument('-cn', '--common-name',
+                      default='',
+                      help="Common Name (eg, your name or your server's " \
+                           "hostname).")
+
+  parser.add_argument('-e', '--email',
+                      default='',
+                      help='Email Address.')
+
+  argument_option_instance = parser.parse_args(list(args))
+  option_dict = {}
+  for argument_key, argument_value in vars(argument_option_instance
+      ).iteritems():
+    if argument_value is not None:
+      option_dict.update({argument_key: argument_value})
+
+  return option_dict
+
+
+def run():
+  ''' Validate the parameters and call the function to create
+    private key and certificate file.
+  '''
+  option_dict = parseArgument(*sys.argv[1:])
+  print createPrivateKeyAndCertificateFile(**option_dict)