rsa_source/rsa/util.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 #  Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
   4 #
   5 #  Licensed under the Apache License, Version 2.0 (the "License");
   6 #  you may not use this file except in compliance with the License.
   7 #  You may obtain a copy of the License at
   8 #
   9 #      http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 #  Unless required by applicable law or agreed to in writing, software
  12 #  distributed under the License is distributed on an "AS IS" BASIS,
  13 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 #  See the License for the specific language governing permissions and
  15 #  limitations under the License.
  16
  17 '''Utility functions.'''
  18
  19 import sys
  20 from optparse import OptionParser
  21
  22 import rsa.key
  23
  24 def private_to_public():
  25     '''Reads a private key and outputs the corresponding public key.'''
  26
  27     # Parse the CLI options
  28     parser = OptionParser(usage='usage: %prog [options]',
  29             description='Reads a private key and outputs the '
  30             'corresponding public key. Both private and public keys use '
  31             'the format described in PKCS#1 v1.5')
  32
  33     parser.add_option('-i', '--input', dest='infilename', type='string',
  34             help='Input filename. Reads from stdin if not specified')
  35     parser.add_option('-o', '--output', dest='outfilename', type='string',
  36             help='Output filename. Writes to stdout of not specified')
  37
  38     parser.add_option('--inform', dest='inform',
  39             help='key format of input - default PEM',
  40             choices=('PEM', 'DER'), default='PEM')
  41
  42     parser.add_option('--outform', dest='outform',
  43             help='key format of output - default PEM',
  44             choices=('PEM', 'DER'), default='PEM')
  45
  46     (cli, cli_args) = parser.parse_args(sys.argv)
  47
  48     # Read the input data
  49     if cli.infilename:
  50         print >>sys.stderr, 'Reading private key from %s in %s format' % \
  51             (cli.infilename, cli.inform)
  52         with open(cli.infilename) as infile:
  53             in_data = infile.read()
  54     else:
  55         print >>sys.stderr, 'Reading private key from stdin in %s format' % \
  56             cli.inform
  57         in_data = sys.stdin.read()
  58
  59
  60     # Take the public fields and create a public key
  61     priv_key = rsa.key.PrivateKey.load_pkcs1(in_data, cli.inform)
  62     pub_key = rsa.key.PublicKey(priv_key.n, priv_key.e)
  63
  64     # Save to the output file
  65     out_data = pub_key.save_pkcs1(cli.outform)
  66
  67     if cli.outfilename:
  68         print >>sys.stderr, 'Writing public key to %s in %s format' % \
  69             (cli.outfilename, cli.outform)
  70         with open(cli.outfilename, 'w') as outfile:
  71             outfile.write(out_data)
  72     else:
  73         print >>sys.stderr, 'Writing public key to stdout in %s format' % \
  74             cli.outform
  75         sys.stdout.write(out_data)
  76
  77