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- # 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
- #
- # https://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."""
-
- import sys
- from optparse import OptionParser
-
- import rsa.key
-
-
- def private_to_public() -> None:
- """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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