/usr/share/pyshared/obnamlib/encryption.py is in obnam 1.6.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
import shutil
import subprocess
import tempfile
import tracing
import obnamlib
def generate_symmetric_key(numbits, filename='/dev/random'):
'''Generate a random key of at least numbits for symmetric encryption.'''
tracing.trace('numbits=%d', numbits)
bytes = (numbits + 7) / 8
f = open(filename, 'rb')
key = f.read(bytes)
f.close()
return key.encode('hex')
class SymmetricKeyCache(object):
'''Cache symmetric keys in memory.'''
def __init__(self):
self.clear()
def get(self, repo, toplevel):
if repo in self.repos and toplevel in self.repos[repo]:
return self.repos[repo][toplevel]
return None
def put(self, repo, toplevel, key):
if repo not in self.repos:
self.repos[repo] = {}
self.repos[repo][toplevel] = key
def clear(self):
self.repos = {}
def _gpg_pipe(args, data, passphrase):
'''Pipe things through gpg.
With the right args, this can be either an encryption or a decryption
operation.
For safety, we give the passphrase to gpg via a file descriptor.
The argument list is modified to include the relevant options for that.
The data is fed to gpg via a temporary file, readable only by
the owner, to avoid congested pipes.
'''
# Open pipe for passphrase, and write it there. If passphrase is
# very long (more than 4 KiB by default), this might block. A better
# implementation would be to have a loop around select(2) to do pipe
# I/O when it can be done without blocking. Patches most welcome.
keypipe = os.pipe()
os.write(keypipe[1], passphrase + '\n')
os.close(keypipe[1])
# Actually run gpg.
argv = ['gpg', '--passphrase-fd', str(keypipe[0]), '-q', '--batch',
'--no-textmode'] + args
tracing.trace('argv=%s', repr(argv))
p = subprocess.Popen(argv, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
out, err = p.communicate(data)
os.close(keypipe[0])
# Return output data, or deal with errors.
if p.returncode: # pragma: no cover
raise obnamlib.EncryptionError(err)
return out
def encrypt_symmetric(cleartext, key):
'''Encrypt data with symmetric encryption.'''
return _gpg_pipe(['-c'], cleartext, key)
def decrypt_symmetric(encrypted, key):
'''Decrypt encrypted data with symmetric encryption.'''
return _gpg_pipe(['-d'], encrypted, key)
def _gpg(args, stdin='', gpghome=None):
'''Run gpg and return its output.'''
env = dict()
env.update(os.environ)
if gpghome is not None:
env['GNUPGHOME'] = gpghome
tracing.trace('gpghome=%s' % gpghome)
argv = ['gpg', '-q', '--batch', '--no-textmode'] + args
tracing.trace('argv=%s', repr(argv))
p = subprocess.Popen(argv, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, env=env)
out, err = p.communicate(stdin)
# Return output data, or deal with errors.
if p.returncode: # pragma: no cover
raise obnamlib.EncryptionError(err)
return out
def get_public_key(keyid, gpghome=None):
'''Return the ASCII armored export form of a given public key.'''
return _gpg(['--export', '--armor', keyid], gpghome=gpghome)
def get_public_key_user_ids(keyid, gpghome=None): # pragma: no cover
'''Return the ASCII armored export form of a given public key.'''
user_ids = []
output = _gpg(['--with-colons', '--list-keys', keyid], gpghome=gpghome)
for line in output.splitlines():
token = line.split(":")
if len(token) >= 10:
user_id = token[9].strip().replace(r'\x3a', ":")
if user_id:
user_ids.append(user_id)
return user_ids
class Keyring(object):
'''A simplistic representation of GnuPG keyrings.
Just enough functionality for obnam's purposes.
'''
_keyring_name = 'pubring.gpg'
def __init__(self, encoded=''):
self._encoded = encoded
self._gpghome = None
self._keyids = None
def _setup(self):
self._gpghome = tempfile.mkdtemp()
f = open(self._keyring, 'wb')
f.write(self._encoded)
f.close()
def _cleanup(self):
shutil.rmtree(self._gpghome)
self._gpghome = None
@property
def _keyring(self):
return os.path.join(self._gpghome, self._keyring_name)
def _real_keyids(self):
output = self.gpg(False, ['--list-keys', '--with-colons'])
keyids = []
for line in output.splitlines():
fields = line.split(':')
if len(fields) >= 5 and fields[0] == 'pub':
keyids.append(fields[4])
return keyids
def keyids(self):
if self._keyids is None:
self._keyids = self._real_keyids()
return self._keyids
def __str__(self):
return self._encoded
def __contains__(self, keyid):
return keyid in self.keyids()
def _reread_keyring(self):
f = open(self._keyring, 'rb')
self._encoded = f.read()
f.close()
self._keyids = None
def add(self, key):
self.gpg(True, ['--import'], stdin=key)
def remove(self, keyid):
self.gpg(True, ['--delete-key', '--yes', keyid])
def gpg(self, reread, *args, **kwargs):
self._setup()
kwargs['gpghome'] = self._gpghome
try:
result = _gpg(*args, **kwargs)
except BaseException: # pragma: no cover
self._cleanup()
raise
else:
if reread:
self._reread_keyring()
self._cleanup()
return result
class SecretKeyring(Keyring):
'''Same as Keyring, but for secret keys.'''
_keyring_name = 'secring.gpg'
def _real_keyids(self):
output = self.gpg(False, ['--list-secret-keys', '--with-colons'])
keyids = []
for line in output.splitlines():
fields = line.split(':')
if len(fields) >= 5 and fields[0] == 'sec':
keyids.append(fields[4])
return keyids
def encrypt_with_keyring(cleartext, keyring):
'''Encrypt data with all keys in a keyring.'''
recipients = []
for keyid in keyring.keyids():
recipients += ['-r', keyid]
return keyring.gpg(False,
['-e',
'--trust-model', 'always',
'--no-encrypt-to',
'--no-default-recipient',
] + recipients,
stdin=cleartext)
def decrypt_with_secret_keys(encrypted, gpghome=None):
'''Decrypt data using secret keys GnuPG finds on its own.'''
return _gpg(['-d'], stdin=encrypted, gpghome=gpghome)
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