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Diffstat (limited to 'rsa/util.py')
-rw-r--r-- | rsa/util.py | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/rsa/util.py b/rsa/util.py new file mode 100644 index 0000000..9c1c863 --- /dev/null +++ b/rsa/util.py @@ -0,0 +1,77 @@ +# -*- 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.''' + +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('--in', dest='infilename', type='string', + help='Input filename. Reads from stdin if not specified') + parser.add_option('--out', 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 >>sys.stderr, 'Reading private key from %s in %s format' % \ + (cli.infilename, cli.inform) + with open(cli.infilename) as infile: + in_data = infile.read() + else: + print >>sys.stderr, 'Reading private key from stdin in %s format' % \ + cli.inform + in_data = sys.stdin.read() + + + # 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 >>sys.stderr, 'Writing public key to %s in %s format' % \ + (cli.outfilename, cli.outform) + with open(cli.outfilename, 'w') as outfile: + outfile.write(out_data) + else: + print >>sys.stderr, 'Writing public key to stdout in %s format' % \ + cli.outform + sys.stdout.write(out_data) + + |