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"""Interface to GNU Privacy Guard (GnuPG)
GnuPGInterface is a Python module to interface with GnuPG.
It concentrates on interacting with GnuPG via filehandles,
providing access to control GnuPG via versatile and extensible means.
This module is based on GnuPG::Interface, a Perl module by the same author.
Normally, using this module will involve creating a
GnuPG object, setting some options in it's 'options' data member
(which is of type Options), creating some pipes
to talk with GnuPG, and then calling the run() method, which will
connect those pipes to the GnuPG process. run() returns a
Process object, which contains the filehandles to talk to GnuPG with.
Example code:
>>> import GnuPGInterface
>>>
>>> plaintext = "Three blind mice"
>>> passphrase = "This is the passphrase"
>>>
>>> gnupg = GnuPGInterface.GnuPG()
>>> gnupg.options.armor = 1
>>> gnupg.options.meta_interactive = 0
>>> gnupg.options.extra_args.append('--no-secmem-warning')
>>>
>>> # Normally we might specify something in
>>> # gnupg.options.recipients, like
>>> # gnupg.options.recipients = [ '0xABCD1234', 'bob@foo.bar' ]
>>> # but since we're doing symmetric-only encryption, it's not needed.
>>> # If you are doing standard, public-key encryption, using
>>> # --encrypt, you will need to specify recipients before
>>> # calling gnupg.run()
>>>
>>> # First we'll encrypt the test_text input symmetrically
>>> p1 = gnupg.run(['--symmetric'],
... create_fhs=['stdin', 'stdout', 'passphrase'])
>>>
>>> p1.handles['passphrase'].write(passphrase)
>>> p1.handles['passphrase'].close()
>>>
>>> p1.handles['stdin'].write(plaintext)
>>> p1.handles['stdin'].close()
>>>
>>> ciphertext = p1.handles['stdout'].read()
>>> p1.handles['stdout'].close()
>>>
>>> # process cleanup
>>> p1.wait()
>>>
>>> # Now we'll decrypt what we just encrypted it,
>>> # using the convience method to get the
>>> # passphrase to GnuPG
>>> gnupg.passphrase = passphrase
>>>
>>> p2 = gnupg.run(['--decrypt'], create_fhs=['stdin', 'stdout'])
>>>
>>> p2.handles['stdin'].write(ciphertext)
>>> p2.handles['stdin'].close()
>>>
>>> decrypted_plaintext = p2.handles['stdout'].read()
>>> p2.handles['stdout'].close()
>>>
>>> # process cleanup
>>> p2.wait()
>>>
>>> # Our decrypted plaintext:
>>> decrypted_plaintext
'Three blind mice'
>>>
>>> # ...and see it's the same as what we orignally encrypted
>>> assert decrypted_plaintext == plaintext, \
"GnuPG decrypted output does not match original input"
>>>
>>>
>>> ##################################################
>>> # Now let's trying using run()'s attach_fhs paramter
>>>
>>> # we're assuming we're running on a unix...
>>> input = open('/etc/motd')
>>>
>>> p1 = gnupg.run(['--symmetric'], create_fhs=['stdout'],
... attach_fhs={'stdin': input})
>>>
>>> # GnuPG will read the stdin from /etc/motd
>>> ciphertext = p1.handles['stdout'].read()
>>>
>>> # process cleanup
>>> p1.wait()
>>>
>>> # Now let's run the output through GnuPG
>>> # We'll write the output to a temporary file,
>>> import tempfile
>>> temp = tempfile.TemporaryFile()
>>>
>>> p2 = gnupg.run(['--decrypt'], create_fhs=['stdin'],
... attach_fhs={'stdout': temp})
>>>
>>> # give GnuPG our encrypted stuff from the first run
>>> p2.handles['stdin'].write(ciphertext)
>>> p2.handles['stdin'].close()
>>>
>>> # process cleanup
>>> p2.wait()
>>>
>>> # rewind the tempfile and see what GnuPG gave us
>>> temp.seek(0)
>>> decrypted_plaintext = temp.read()
>>>
>>> # compare what GnuPG decrypted with our original input
>>> input.seek(0)
>>> input_data = input.read()
>>>
>>> assert decrypted_plaintext == input_data, \
"GnuPG decrypted output does not match original input"
To do things like public-key encryption, simply pass do something
like:
gnupg.passphrase = 'My passphrase'
gnupg.options.recipients = [ 'bob@foobar.com' ]
gnupg.run( ['--sign', '--encrypt'], create_fhs=..., attach_fhs=...)
Here is an example of subclassing GnuPGInterface.GnuPG,
so that it has an encrypt_string() method that returns
ciphertext.
>>> import GnuPGInterface
>>>
>>> class MyGnuPG(GnuPGInterface.GnuPG):
...
... def __init__(self):
... GnuPGInterface.GnuPG.__init__(self)
... self.setup_my_options()
...
... def setup_my_options(self):
... self.options.armor = 1
... self.options.meta_interactive = 0
... self.options.extra_args.append('--no-secmem-warning')
...
... def encrypt_string(self, string, recipients):
... gnupg.options.recipients = recipients # a list!
...
... proc = gnupg.run(['--encrypt'], create_fhs=['stdin', 'stdout'])
...
... proc.handles['stdin'].write(string)
... proc.handles['stdin'].close()
...
... output = proc.handles['stdout'].read()
... proc.handles['stdout'].close()
...
... proc.wait()
... return output
...
>>> gnupg = MyGnuPG()
>>> ciphertext = gnupg.encrypt_string("The secret", ['0x260C4FA3'])
>>>
>>> # just a small sanity test here for doctest
>>> import types
>>> assert isinstance(ciphertext, types.StringType), \
"What GnuPG gave back is not a string!"
Here is an example of generating a key:
>>> import GnuPGInterface
>>> gnupg = GnuPGInterface.GnuPG()
>>> gnupg.options.meta_interactive = 0
>>>
>>> # We will be creative and use the logger filehandle to capture
>>> # what GnuPG says this time, instead stderr; no stdout to listen to,
>>> # but we capture logger to surpress the dry-run command.
>>> # We also have to capture stdout since otherwise doctest complains;
>>> # Normally you can let stdout through when generating a key.
>>>
>>> proc = gnupg.run(['--gen-key'], create_fhs=['stdin', 'stdout',
... 'logger'])
>>>
>>> proc.handles['stdin'].write('''Key-Type: DSA
... Key-Length: 1024
... # We are only testing syntax this time, so dry-run
... %dry-run
... Subkey-Type: ELG-E
... Subkey-Length: 1024
... Name-Real: Joe Tester
... Name-Comment: with stupid passphrase
... Name-Email: joe@foo.bar
... Expire-Date: 2y
... Passphrase: abc
... %pubring foo.pub
... %secring foo.sec
... ''')
>>>
>>> proc.handles['stdin'].close()
>>>
>>> report = proc.handles['logger'].read()
>>> proc.handles['logger'].close()
>>>
>>> proc.wait()
COPYRIGHT:
Copyright (C) 2001 Frank J. Tobin, ftobin@neverending.org
LICENSE:
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
or see http://www.gnu.org/copyleft/lesser.html
"""
import os
import sys
import fcntl
__author__ = "Frank J. Tobin, ftobin@neverending.org"
__version__ = "0.3.2"
__revision__ = "$Id: GnuPGInterface.py,v 1.22 2002/01/11 20:22:04 ftobin Exp $"
# "standard" filehandles attached to processes
_stds = [ 'stdin', 'stdout', 'stderr' ]
# the permissions each type of fh needs to be opened with
_fd_modes = { 'stdin': 'w',
'stdout': 'r',
'stderr': 'r',
'passphrase': 'w',
'command': 'w',
'logger': 'r',
'status': 'r'
}
# correlation between handle names and the arguments we'll pass
_fd_options = { 'passphrase': '--passphrase-fd',
'logger': '--logger-fd',
'status': '--status-fd',
'command': '--command-fd' }
class GnuPG:
"""Class instances represent GnuPG.
Instance attributes of a GnuPG object are:
* call -- string to call GnuPG with. Defaults to "gpg"
* passphrase -- Since it is a common operation
to pass in a passphrase to GnuPG,
and working with the passphrase filehandle mechanism directly
can be mundane, if set, the passphrase attribute
works in a special manner. If the passphrase attribute is set,
and no passphrase file object is sent in to run(),
then GnuPG instnace will take care of sending the passphrase to
GnuPG, the executable instead of having the user sent it in manually.
* options -- Object of type GnuPGInterface.Options.
Attribute-setting in options determines
the command-line options used when calling GnuPG.
"""
def __init__(self):
self.call = 'gpg'
self.passphrase = None
self.options = Options()
def run(self, gnupg_commands, args=None, create_fhs=None, attach_fhs=None):
"""Calls GnuPG with the list of string commands gnupg_commands,
complete with prefixing dashes.
For example, gnupg_commands could be
'["--sign", "--encrypt"]'
Returns a GnuPGInterface.Process object.
args is an optional list of GnuPG command arguments (not options),
such as keyID's to export, filenames to process, etc.
create_fhs is an optional list of GnuPG filehandle
names that will be set as keys of the returned Process object's
'handles' attribute. The generated filehandles can be used
to communicate with GnuPG via standard input, standard output,
the status-fd, passphrase-fd, etc.
Valid GnuPG filehandle names are:
* stdin
* stdout
* stderr
* status
* passphase
* command
* logger
The purpose of each filehandle is described in the GnuPG
documentation.
attach_fhs is an optional dictionary with GnuPG filehandle
names mapping to opened files. GnuPG will read or write
to the file accordingly. For example, if 'my_file' is an
opened file and 'attach_fhs[stdin] is my_file', then GnuPG
will read its standard input from my_file. This is useful
if you want GnuPG to read/write to/from an existing file.
For instance:
f = open("encrypted.gpg")
gnupg.run(["--decrypt"], attach_fhs={'stdin': f})
Using attach_fhs also helps avoid system buffering
issues that can arise when using create_fhs, which
can cause the process to deadlock.
If not mentioned in create_fhs or attach_fhs,
GnuPG filehandles which are a std* (stdin, stdout, stderr)
are defaulted to the running process' version of handle.
Otherwise, that type of handle is simply not used when calling GnuPG.
For example, if you do not care about getting data from GnuPG's
status filehandle, simply do not specify it.
run() returns a Process() object which has a 'handles'
which is a dictionary mapping from the handle name
(such as 'stdin' or 'stdout') to the respective
newly-created FileObject connected to the running GnuPG process.
For instance, if the call was
process = gnupg.run(["--decrypt"], stdin=1)
after run returns 'process.handles["stdin"]'
is a FileObject connected to GnuPG's standard input,
and can be written to.
"""
if args == None: args = []
if create_fhs == None: create_fhs = []
if attach_fhs == None: attach_fhs = {}
for std in _stds:
if not attach_fhs.has_key(std) \
and std not in create_fhs:
attach_fhs.setdefault(std, getattr(sys, std))
handle_passphrase = 0
if self.passphrase != None \
and not attach_fhs.has_key('passphrase') \
and 'passphrase' not in create_fhs:
handle_passphrase = 1
create_fhs.append('passphrase')
process = self._attach_fork_exec(gnupg_commands, args,
create_fhs, attach_fhs)
if handle_passphrase:
passphrase_fh = process.handles['passphrase']
passphrase_fh.write( self.passphrase )
passphrase_fh.close()
del process.handles['passphrase']
return process
def _attach_fork_exec(self, gnupg_commands, args, create_fhs, attach_fhs):
"""This is like run(), but without the passphrase-helping
(note that run() calls this)."""
process = Process()
for fh_name in create_fhs + attach_fhs.keys():
if not _fd_modes.has_key(fh_name):
raise KeyError, \
"unrecognized filehandle name '%s'; must be one of %s" \
% (fh_name, _fd_modes.keys())
for fh_name in create_fhs:
# make sure the user doesn't specify a filehandle
# to be created *and* attached
if attach_fhs.has_key(fh_name):
raise ValueError, \
"cannot have filehandle '%s' in both create_fhs and attach_fhs" \
% fh_name
pipe = os.pipe()
# fix by drt@un.bewaff.net noting
# that since pipes are unidirectional on some systems,
# so we have to 'turn the pipe around'
# if we are writing
if _fd_modes[fh_name] == 'w': pipe = (pipe[1], pipe[0])
process._pipes[fh_name] = Pipe(pipe[0], pipe[1], 0)
for fh_name, fh in attach_fhs.items():
process._pipes[fh_name] = Pipe(fh.fileno(), fh.fileno(), 1)
process.pid = os.fork()
if process.pid == 0: self._as_child(process, gnupg_commands, args)
return self._as_parent(process)
def _as_parent(self, process):
"""Stuff run after forking in parent"""
for k, p in process._pipes.items():
if not p.direct:
os.close(p.child)
process.handles[k] = os.fdopen(p.parent, _fd_modes[k])
# user doesn't need these
del process._pipes
return process
def _as_child(self, process, gnupg_commands, args):
"""Stuff run after forking in child"""
# child
for std in _stds:
p = process._pipes[std]
os.dup2( p.child, getattr(sys, "__%s__" % std).fileno() )
for k, p in process._pipes.items():
if p.direct and k not in _stds:
# we want the fh to stay open after execing
fcntl.fcntl( p.child, fcntl.F_SETFD, 0 )
fd_args = []
for k, p in process._pipes.items():
# set command-line options for non-standard fds
if k not in _stds:
fd_args.extend([ _fd_options[k], "%d" % p.child ])
if not p.direct: os.close(p.parent)
command = [ self.call ] + fd_args + self.options.get_args() \
+ gnupg_commands + args
os.execvp( command[0], command )
class Pipe:
"""simple struct holding stuff about pipes we use"""
def __init__(self, parent, child, direct):
self.parent = parent
self.child = child
self.direct = direct
class Options:
"""Objects of this class encompass options passed to GnuPG.
This class is responsible for determining command-line arguments
which are based on options. It can be said that a GnuPG
object has-a Options object in its options attribute.
Attributes which correlate directly to GnuPG options:
Each option here defaults to false or None, and is described in
GnuPG documentation.
Booleans (set these attributes to booleans)
* armor
* no_greeting
* no_verbose
* quiet
* batch
* always_trust
* rfc1991
* openpgp
* force_v3_sigs
* no_options
* textmode
Strings (set these attributes to strings)
* homedir
* default_key
* comment
* compress_algo
* options
Lists (set these attributes to lists)
* recipients (***NOTE*** plural of 'recipient')
* encrypt_to
Meta options
Meta options are options provided by this module that do
not correlate directly to any GnuPG option by name,
but are rather bundle of options used to accomplish
a specific goal, such as obtaining compatibility with PGP 5.
The actual arguments each of these reflects may change with time. Each
defaults to false unless otherwise specified.
meta_pgp_5_compatible -- If true, arguments are generated to try
to be compatible with PGP 5.x.
meta_pgp_2_compatible -- If true, arguments are generated to try
to be compatible with PGP 2.x.
meta_interactive -- If false, arguments are generated to try to
help the using program use GnuPG in a non-interactive
environment, such as CGI scripts. Default is true.
extra_args -- Extra option arguments may be passed in
via the attribute extra_args, a list.
>>> import GnuPGInterface
>>>
>>> gnupg = GnuPGInterface.GnuPG()
>>> gnupg.options.armor = 1
>>> gnupg.options.recipients = ['Alice', 'Bob']
>>> gnupg.options.extra_args = ['--no-secmem-warning']
>>>
>>> # no need for users to call this normally; just for show here
>>> gnupg.options.get_args()
['--armor', '--recipient', 'Alice', '--recipient', 'Bob', '--no-secmem-warning']
"""
def __init__(self):
# booleans
self.armor = 0
self.no_greeting = 0
self.verbose = 0
self.no_verbose = 0
self.quiet = 0
self.batch = 0
self.always_trust = 0
self.rfc1991 = 0
self.openpgp = 0
self.force_v3_sigs = 0
self.no_options = 0
self.textmode = 0
# meta-option booleans
self.meta_pgp_5_compatible = 0
self.meta_pgp_2_compatible = 0
self.meta_interactive = 1
# strings
self.homedir = None
self.default_key = None
self.comment = None
self.compress_algo = None
self.options = None
# lists
self.encrypt_to = []
self.recipients = []
# miscellaneous arguments
self.extra_args = []
def get_args( self ):
"""Generate a list of GnuPG arguments based upon attributes."""
return self.get_meta_args() + self.get_standard_args() + self.extra_args
def get_standard_args( self ):
"""Generate a list of standard, non-meta or extra arguments"""
args = []
if self.homedir != None: args.extend( [ '--homedir', self.homedir ] )
if self.options != None: args.extend( [ '--options', self.options ] )
if self.comment != None: args.extend( [ '--comment', self.comment ] )
if self.compress_algo != None: args.extend( [ '--compress-algo', self.compress_algo ] )
if self.default_key != None: args.extend( [ '--default-key', self.default_key ] )
if self.no_options: args.append( '--no-options' )
if self.armor: args.append( '--armor' )
if self.textmode: args.append( '--textmode' )
if self.no_greeting: args.append( '--no-greeting' )
if self.verbose: args.append( '--verbose' )
if self.no_verbose: args.append( '--no-verbose' )
if self.quiet: args.append( '--quiet' )
if self.batch: args.append( '--batch' )
if self.always_trust: args.append( '--always-trust' )
if self.force_v3_sigs: args.append( '--force-v3-sigs' )
if self.rfc1991: args.append( '--rfc1991' )
if self.openpgp: args.append( '--openpgp' )
for r in self.recipients: args.extend( [ '--recipient', r ] )
for r in self.encrypt_to: args.extend( [ '--encrypt-to', r ] )
return args
def get_meta_args( self ):
"""Get a list of generated meta-arguments"""
args = []
if self.meta_pgp_5_compatible: args.extend( [ '--compress-algo', '1',
'--force-v3-sigs'
] )
if self.meta_pgp_2_compatible: args.append( '--rfc1991' )
if not self.meta_interactive: args.extend( [ '--batch', '--no-tty' ] )
return args
class Process:
"""Objects of this class encompass properties of a GnuPG
process spawned by GnuPG.run().
# gnupg is a GnuPG object
process = gnupg.run( [ '--decrypt' ], stdout = 1 )
out = process.handles['stdout'].read()
...
os.waitpid( process.pid, 0 )
Data Attributes
handles -- This is a map of filehandle-names to
the file handles, if any, that were requested via run() and hence
are connected to the running GnuPG process. Valid names
of this map are only those handles that were requested.
pid -- The PID of the spawned GnuPG process.
Useful to know, since once should call
os.waitpid() to clean up the process, especially
if multiple calls are made to run().
"""
def __init__(self):
self._pipes = {}
self.handles = {}
self.pid = None
self._waited = None
def wait(self):
"""Wait on the process to exit, allowing for child cleanup.
Will raise an IOError if the process exits non-zero."""
e = os.waitpid(self.pid, 0)[1]
if e != 0:
raise IOError, "GnuPG exited non-zero, with code %d" % (e << 8)
def _run_doctests():
import doctest, GnuPGInterface
return doctest.testmod(GnuPGInterface)
# deprecated
GnuPGInterface = GnuPG
if __name__ == '__main__':
_run_doctests()
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