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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Utility functions.'''
from __future__ import with_statement, print_function
import sys
from optparse import OptionParser
import rsa.key
def private_to_public():
'''Reads a private key and outputs the corresponding public key.'''
# Parse the CLI options
parser = OptionParser(usage='usage: %prog [options]',
description='Reads a private key and outputs the '
'corresponding public key. Both private and public keys use '
'the format described in PKCS#1 v1.5')
parser.add_option('-i', '--input', dest='infilename', type='string',
help='Input filename. Reads from stdin if not specified')
parser.add_option('-o', '--output', dest='outfilename', type='string',
help='Output filename. Writes to stdout of not specified')
parser.add_option('--inform', dest='inform',
help='key format of input - default PEM',
choices=('PEM', 'DER'), default='PEM')
parser.add_option('--outform', dest='outform',
help='key format of output - default PEM',
choices=('PEM', 'DER'), default='PEM')
(cli, cli_args) = parser.parse_args(sys.argv)
# Read the input data
if cli.infilename:
print('Reading private key from %s in %s format' % \
(cli.infilename, cli.inform), file=sys.stderr)
with open(cli.infilename, 'rb') as infile:
in_data = infile.read()
else:
print('Reading private key from stdin in %s format' % cli.inform,
file=sys.stderr)
in_data = sys.stdin.read().encode('ascii')
assert type(in_data) == bytes, type(in_data)
# Take the public fields and create a public key
priv_key = rsa.key.PrivateKey.load_pkcs1(in_data, cli.inform)
pub_key = rsa.key.PublicKey(priv_key.n, priv_key.e)
# Save to the output file
out_data = pub_key.save_pkcs1(cli.outform)
if cli.outfilename:
print('Writing public key to %s in %s format' % \
(cli.outfilename, cli.outform), file=sys.stderr)
with open(cli.outfilename, 'wb') as outfile:
outfile.write(out_data)
else:
print('Writing public key to stdout in %s format' % cli.outform,
file=sys.stderr)
sys.stdout.write(out_data.decode('ascii'))
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