gnupg.py

""" A wrapper for the 'gpg' command::

Portions of this module are derived from A.M. Kuchling's well-designed
GPG.py, using Richard Jones' updated version 1.3, which can be found
in the pycrypto CVS repository on Sourceforge:

http://pycrypto.cvs.sourceforge.net/viewvc/pycrypto/gpg/GPG.py

This module is *not* forward-compatible with amk's; some of the
old interface has changed.  For instance, since I've added decrypt
functionality, I elected to initialize with a 'gnupghome' argument
instead of 'keyring', so that gpg can find both the public and secret
keyrings.  I've also altered some of the returned objects in order for
the caller to not have to know as much about the internals of the
result classes.

While the rest of ISconf is released under the GPL, I am releasing
this single file under the same terms that A.M. Kuchling used for
pycrypto.

Steve Traugott, stevegt@terraluna.org
Thu Jun 23 21:27:20 PDT 2005

This version of the module has been modified from Steve Traugott's version
(see http://trac.t7a.org/isconf/browser/trunk/lib/python/isconf/GPG.py) by
Vinay Sajip to make use of the subprocess module (Steve's version uses os.fork()
and so does not work on Windows). Renamed to gnupg.py to avoid confusion with
the previous versions.

Modifications Copyright (C) 2008-2018 Vinay Sajip. All rights reserved.

A unittest harness (test_gnupg.py) has also been added.
"""

__version__ = "0.4.3"
__author__ = "Vinay Sajip"
__date__  = "$13-Jun-2018 12:11:43$"

try:
    from io import StringIO
except ImportError:  # pragma: no cover
    from cStringIO import StringIO

import codecs
import locale
import logging
import os
import re
import socket
from subprocess import Popen
from subprocess import PIPE
import sys
import threading

STARTUPINFO = None
if os.name == 'nt':  # pragma: no cover
    try:
        from subprocess import STARTUPINFO, STARTF_USESHOWWINDOW, SW_HIDE
    except ImportError:
        STARTUPINFO = None

try:
    import logging.NullHandler as NullHandler
except ImportError:
    class NullHandler(logging.Handler):
        def handle(self, record):
            pass
try:
    unicode
    _py3k = False
    string_types = basestring
    text_type = unicode
except NameError:
    _py3k = True
    string_types = str
    text_type = str

logger = logging.getLogger(__name__)
if not logger.handlers:
    logger.addHandler(NullHandler())

# We use the test below because it works for Jython as well as CPython
if os.path.__name__ == 'ntpath':  # pragma: no cover
    # On Windows, we don't need shell quoting, other than worrying about
    # paths with spaces in them.
    def shell_quote(s):
        return '"%s"' % s
else:
    # Section copied from sarge

    # This regex determines which shell input needs quoting
    # because it may be unsafe
    UNSAFE = re.compile(r'[^\w%+,./:=@-]')

    def shell_quote(s):
        """
        Quote text so that it is safe for Posix command shells.

        For example, "*.py" would be converted to "'*.py'". If the text is
        considered safe it is returned unquoted.

        :param s: The value to quote
        :type s: str (or unicode on 2.x)
        :return: A safe version of the input, from the point of view of Posix
                 command shells
        :rtype: The passed-in type
        """
        if not isinstance(s, string_types):  # pragma: no cover
            raise TypeError('Expected string type, got %s' % type(s))
        if not s:
            result = "''"
        elif not UNSAFE.search(s):
            result = s
        else:
            result = "'%s'" % s.replace("'", r"'\''")
        return result

    # end of sarge code

# Now that we use shell=False, we shouldn't need to quote arguments.
# Use no_quote instead of shell_quote to remind us of where quoting
# was needed. However, note that we still need, on 2.x, to encode any
# Unicode argument with the file system encoding - see Issue #41 and
# Python issue #1759845 ("subprocess.call fails with unicode strings in
# command line").

# Allows the encoding used to be overridden in special cases by setting
# this module attribute appropriately.
fsencoding = sys.getfilesystemencoding()

def no_quote(s):
    if not _py3k and isinstance(s, text_type):
        s = s.encode(fsencoding)
    return s

def _copy_data(instream, outstream):
    # Copy one stream to another
    sent = 0
    if hasattr(sys.stdin, 'encoding'):
        enc = sys.stdin.encoding
    else:  # pragma: no cover
        enc = 'ascii'
    while True:
        # See issue #39: read can fail when e.g. a text stream is provided
        # for what is actually a binary file
        try:
            data = instream.read(1024)
        except UnicodeError:
            logger.warning('Exception occurred while reading', exc_info=1)
            break
        if not data:
            break
        sent += len(data)
        # logger.debug("sending chunk (%d): %r", sent, data[:256])
        try:
            outstream.write(data)
        except UnicodeError:  # pragma: no cover
            outstream.write(data.encode(enc))
        except:
            # Can sometimes get 'broken pipe' errors even when the data has all
            # been sent
            logger.exception('Error sending data')
            break
    try:
        outstream.close()
    except IOError:  # pragma: no cover
        logger.warning('Exception occurred while closing: ignored', exc_info=1)
    logger.debug("closed output, %d bytes sent", sent)

def _threaded_copy_data(instream, outstream):
    wr = threading.Thread(target=_copy_data, args=(instream, outstream))
    wr.setDaemon(True)
    logger.debug('data copier: %r, %r, %r', wr, instream, outstream)
    wr.start()
    return wr

def _write_passphrase(stream, passphrase, encoding):
    passphrase = '%s\n' % passphrase
    passphrase = passphrase.encode(encoding)
    stream.write(passphrase)
    logger.debug('Wrote passphrase')

def _is_sequence(instance):
    return isinstance(instance, (list, tuple, set, frozenset))

def _make_memory_stream(s):
    try:
        from io import BytesIO
        rv = BytesIO(s)
    except ImportError:  # pragma: no cover
        rv = StringIO(s)
    return rv

def _make_binary_stream(s, encoding):
    if _py3k:
        if isinstance(s, str):
            s = s.encode(encoding)
    else:
        if type(s) is not str:
            s = s.encode(encoding)
    return _make_memory_stream(s)

class Verify(object):
    "Handle status messages for --verify"

    TRUST_UNDEFINED = 0
    TRUST_NEVER = 1
    TRUST_MARGINAL = 2
    TRUST_FULLY = 3
    TRUST_ULTIMATE = 4

    TRUST_LEVELS = {
        "TRUST_UNDEFINED" : TRUST_UNDEFINED,
        "TRUST_NEVER" : TRUST_NEVER,
        "TRUST_MARGINAL" : TRUST_MARGINAL,
        "TRUST_FULLY" : TRUST_FULLY,
        "TRUST_ULTIMATE" : TRUST_ULTIMATE,
    }

    # for now, just the most common error codes. This can be expanded as and
    # when reports come in of other errors.
    GPG_SYSTEM_ERROR_CODES = {
        1: 'permission denied',
        35: 'file exists',
        81: 'file not found',
        97: 'not a directory',
    }

    GPG_ERROR_CODES = {
        11: 'incorrect passphrase',
    }

    def __init__(self, gpg):
        self.gpg = gpg
        self.valid = False
        self.fingerprint = self.creation_date = self.timestamp = None
        self.signature_id = self.key_id = None
        self.username = None
        self.key_id = None
        self.key_status = None
        self.status = None
        self.pubkey_fingerprint = None
        self.expire_timestamp = None
        self.sig_timestamp = None
        self.trust_text = None
        self.trust_level = None

    def __nonzero__(self):
        return self.valid

    __bool__ = __nonzero__

    def handle_status(self, key, value):
        if key in self.TRUST_LEVELS:
            self.trust_text = key
            self.trust_level = self.TRUST_LEVELS[key]
        elif key in ("WARNING", "ERROR"):
            logger.warning('potential problem: %s: %s', key, value)
        elif key == "BADSIG":  # pragma: no cover
            self.valid = False
            self.status = 'signature bad'
            self.key_id, self.username = value.split(None, 1)
        elif key == "ERRSIG":  # pragma: no cover
            self.valid = False
            (self.key_id,
             algo, hash_algo,
             cls,
             self.timestamp) = value.split()[:5]
            self.status = 'signature error'
        elif key == "EXPSIG":  # pragma: no cover
            self.valid = False
            self.status = 'signature expired'
            self.key_id, self.username = value.split(None, 1)
        elif key == "GOODSIG":
            self.valid = True
            self.status = 'signature good'
            self.key_id, self.username = value.split(None, 1)
        elif key == "VALIDSIG":
            (self.fingerprint,
             self.creation_date,
             self.sig_timestamp,
             self.expire_timestamp) = value.split()[:4]
            # may be different if signature is made with a subkey
            self.pubkey_fingerprint = value.split()[-1]
            self.status = 'signature valid'
        elif key == "SIG_ID":
            (self.signature_id,
             self.creation_date, self.timestamp) = value.split()
        elif key == "DECRYPTION_FAILED":  # pragma: no cover
            self.valid = False
            self.key_id = value
            self.status = 'decryption failed'
        elif key == "NO_PUBKEY":  # pragma: no cover
            self.valid = False
            self.key_id = value
            self.status = 'no public key'
        elif key in ("EXPKEYSIG", "REVKEYSIG"):  # pragma: no cover
            # signed with expired or revoked key
            self.valid = False
            self.key_id = value.split()[0]
            if key == "EXPKEYSIG":
                self.key_status = 'signing key has expired'
            else:
                self.key_status = 'signing key was revoked'
            self.status = self.key_status
        elif key in ("UNEXPECTED", "FAILURE"):  # pragma: no cover
            self.valid = False
            self.key_id = value
            if key == "UNEXPECTED":
                self.status = 'unexpected data'
            else:
                # N.B. there might be other reasons. For example, if an output
                # file can't  be created - /dev/null/foo will lead to a
                # "not a directory" error, but which is not sent as a status
                # message with the [GNUPG:] prefix. Similarly if you try to
                # write to "/etc/foo" as a non-root user, a "permission denied"
                # error will be sent as a non-status message.
                message = 'error - %s' % value
                parts = value.split()
                if parts[-1].isdigit():
                    code = int(parts[-1])
                    system_error = bool(code & 0x8000)
                    code = code & 0x7FFF
                    if system_error:
                        mapping = self.GPG_SYSTEM_ERROR_CODES
                    else:
                        mapping = self.GPG_ERROR_CODES
                    if code in mapping:
                        message = mapping[code]
                if not self.status:
                    self.status = message
        elif key in ("DECRYPTION_INFO", "PLAINTEXT", "PLAINTEXT_LENGTH",
                     "NO_SECKEY", "BEGIN_SIGNING"):
            pass
        else:  # pragma: no cover
            logger.debug('message ignored: %s, %s', key, value)

class ImportResult(object):
    "Handle status messages for --import"

    counts = '''count no_user_id imported imported_rsa unchanged
            n_uids n_subk n_sigs n_revoc sec_read sec_imported
            sec_dups not_imported'''.split()
    def __init__(self, gpg):
        self.gpg = gpg
        self.imported = []
        self.results = []
        self.fingerprints = []
        for result in self.counts:
            setattr(self, result, None)

    def __nonzero__(self):
        if self.not_imported: return False
        if not self.fingerprints: return False
        return True

    __bool__ = __nonzero__

    ok_reason = {
        '0': 'Not actually changed',
        '1': 'Entirely new key',
        '2': 'New user IDs',
        '4': 'New signatures',
        '8': 'New subkeys',
        '16': 'Contains private key',
    }

    problem_reason = {
        '0': 'No specific reason given',
        '1': 'Invalid Certificate',
        '2': 'Issuer Certificate missing',
        '3': 'Certificate Chain too long',
        '4': 'Error storing certificate',
    }

    def handle_status(self, key, value):
        if key in ("WARNING", "ERROR"):
            logger.warning('potential problem: %s: %s', key, value)
        elif key in ("IMPORTED", "KEY_CONSIDERED"):
            # this duplicates info we already see in import_ok & import_problem
            pass
        elif key == "NODATA":  # pragma: no cover
            self.results.append({'fingerprint': None,
                'problem': '0', 'text': 'No valid data found'})
        elif key == "IMPORT_OK":
            reason, fingerprint = value.split()
            reasons = []
            for code, text in list(self.ok_reason.items()):
                if int(reason) | int(code) == int(reason):
                    reasons.append(text)
            reasontext = '\n'.join(reasons) + "\n"
            self.results.append({'fingerprint': fingerprint,
                'ok': reason, 'text': reasontext})
            self.fingerprints.append(fingerprint)
        elif key == "IMPORT_PROBLEM":  # pragma: no cover
            try:
                reason, fingerprint = value.split()
            except:
                reason = value
                fingerprint = '<unknown>'
            self.results.append({'fingerprint': fingerprint,
                'problem': reason, 'text': self.problem_reason[reason]})
        elif key == "IMPORT_RES":
            import_res = value.split()
            for i, count in enumerate(self.counts):
                setattr(self, count, int(import_res[i]))
        elif key == "KEYEXPIRED":  # pragma: no cover
            self.results.append({'fingerprint': None,
                'problem': '0', 'text': 'Key expired'})
        elif key == "SIGEXPIRED":  # pragma: no cover
            self.results.append({'fingerprint': None,
                'problem': '0', 'text': 'Signature expired'})
        elif key == "FAILURE":  # pragma: no cover
            self.results.append({'fingerprint': None,
                'problem': '0', 'text': 'Other failure'})
        else:  # pragma: no cover
            logger.debug('message ignored: %s, %s', key, value)

    def summary(self):
        l = []
        l.append('%d imported' % self.imported)
        if self.not_imported:  # pragma: no cover
            l.append('%d not imported' % self.not_imported)
        return ', '.join(l)

ESCAPE_PATTERN = re.compile(r'\\x([0-9a-f][0-9a-f])', re.I)
BASIC_ESCAPES = {
    r'\n': '\n',
    r'\r': '\r',
    r'\f': '\f',
    r'\v': '\v',
    r'\b': '\b',
    r'\0': '\0',
}

class SendResult(object):
    def __init__(self, gpg):
        self.gpg = gpg

    def handle_status(self, key, value):
        logger.debug('SendResult: %s: %s', key, value)

def _set_fields(target, fieldnames, args):
    for i, var in enumerate(fieldnames):
        if i < len(args):
            target[var] = args[i]
        else:
            target[var] = 'unavailable'

class SearchKeys(list):
    ''' Handle status messages for --search-keys.

        Handle pub and uid (relating the latter to the former).

        Don't care about the rest
    '''

    UID_INDEX = 1
    FIELDS = 'type keyid algo length date expires'.split()

    def __init__(self, gpg):
        self.gpg = gpg
        self.curkey = None
        self.fingerprints = []
        self.uids = []

    def get_fields(self, args):
        result = {}
        _set_fields(result, self.FIELDS, args)
        result['uids'] = []
        result['sigs'] = []
        return result

    def pub(self, args):
        self.curkey = curkey = self.get_fields(args)
        self.append(curkey)

    def uid(self, args):
        uid = args[self.UID_INDEX]
        uid = ESCAPE_PATTERN.sub(lambda m: chr(int(m.group(1), 16)), uid)
        for k, v in BASIC_ESCAPES.items():
            uid = uid.replace(k, v)
        self.curkey['uids'].append(uid)
        self.uids.append(uid)

    def handle_status(self, key, value):  # pragma: no cover
        pass

class ListKeys(SearchKeys):
    ''' Handle status messages for --list-keys, --list-sigs.

        Handle pub and uid (relating the latter to the former).

        Don't care about (info from src/DETAILS):

        crt = X.509 certificate
        crs = X.509 certificate and private key available
        uat = user attribute (same as user id except for field 10).
        sig = signature
        rev = revocation signature
        pkd = public key data (special field format, see below)
        grp = reserved for gpgsm
        rvk = revocation key
    '''

    UID_INDEX = 9
    FIELDS = 'type trust length algo keyid date expires dummy ownertrust uid sig cap issuer flag token hash curve compliance updated origin'.split()

    def __init__(self, gpg):
        super(ListKeys, self).__init__(gpg)
        self.in_subkey = False
        self.key_map = {}

    def key(self, args):
        self.curkey = curkey = self.get_fields(args)
        if curkey['uid']:
            curkey['uids'].append(curkey['uid'])
        del curkey['uid']
        curkey['subkeys'] = []
        self.append(curkey)
        self.in_subkey = False

    pub = sec = key

    def fpr(self, args):
        fp = args[9]
        if fp in self.key_map:  # pragma: no cover
            raise ValueError('Unexpected fingerprint collision: %s' % fp)
        if not self.in_subkey:
            self.curkey['fingerprint'] = fp
            self.fingerprints.append(fp)
            self.key_map[fp] = self.curkey
        else:
            self.curkey['subkeys'][-1].append(fp)
            self.key_map[fp] = self.curkey

    def _collect_subkey_info(self, curkey, args):
        info_map = curkey.setdefault('subkey_info', {})
        info = {}
        _set_fields(info, self.FIELDS, args)
        info_map[args[4]] = info

    def sub(self, args):
        # See issue #81. We create a dict with more information about
        # subkeys, but for backward compatibility reason, have to add it in
        # as a separate entry 'subkey_info'
        subkey = [args[4], args[11]]    # keyid, type
        self.curkey['subkeys'].append(subkey)
        self._collect_subkey_info(self.curkey, args)
        self.in_subkey = True

    def ssb(self, args):
        subkey = [args[4], None]    # keyid, type
        self.curkey['subkeys'].append(subkey)
        self._collect_subkey_info(self.curkey, args)
        self.in_subkey = True

    def sig(self, args):
        # keyid, uid, sigclass
        self.curkey['sigs'].append((args[4], args[9], args[10]))

class ScanKeys(ListKeys):
    ''' Handle status messages for --with-fingerprint.'''

    def sub(self, args):
        # --with-fingerprint --with-colons somehow outputs fewer colons,
        # use the last value args[-1] instead of args[11]
        subkey = [args[4], args[-1]]
        self.curkey['subkeys'].append(subkey)
        self._collect_subkey_info(self.curkey, args)
        self.in_subkey = True

class TextHandler(object):
    def _as_text(self):
        return self.data.decode(self.gpg.encoding, self.gpg.decode_errors)

    if _py3k:
        __str__ = _as_text
    else:
        __unicode__ = _as_text

        def __str__(self):
            return self.data


class Crypt(Verify, TextHandler):
    "Handle status messages for --encrypt and --decrypt"
    def __init__(self, gpg):
        Verify.__init__(self, gpg)
        self.data = ''
        self.ok = False
        self.status = ''
        self.key_id = None

    def __nonzero__(self):
        if self.ok: return True
        return False

    __bool__ = __nonzero__

    def handle_status(self, key, value):
        if key in ("WARNING", "ERROR"):
            logger.warning('potential problem: %s: %s', key, value)
        elif key == "NODATA":
            self.status = "no data was provided"
        elif key in ("NEED_PASSPHRASE", "BAD_PASSPHRASE", "GOOD_PASSPHRASE",
                     "MISSING_PASSPHRASE", "DECRYPTION_FAILED",
                     "KEY_NOT_CREATED", "NEED_PASSPHRASE_PIN"):
            self.status = key.replace("_", " ").lower()
        elif key == "NEED_PASSPHRASE_SYM":
            self.status = 'need symmetric passphrase'
        elif key == "BEGIN_DECRYPTION":
            self.status = 'decryption incomplete'
        elif key == "BEGIN_ENCRYPTION":
            self.status = 'encryption incomplete'
        elif key == "DECRYPTION_OKAY":
            self.status = 'decryption ok'
            self.ok = True
        elif key == "END_ENCRYPTION":
            self.status = 'encryption ok'
            self.ok = True
        elif key == "INV_RECP":  # pragma: no cover
            self.status = 'invalid recipient'
        elif key == "KEYEXPIRED":  # pragma: no cover
            self.status = 'key expired'
        elif key == "SIG_CREATED":  # pragma: no cover
            self.status = 'sig created'
        elif key == "SIGEXPIRED":  # pragma: no cover
            self.status = 'sig expired'
        elif key == "ENC_TO":  # pragma: no cover
            # ENC_TO <long_keyid> <keytype> <keylength>
            self.key_id = value.split(' ', 1)[0]
        elif key in ("USERID_HINT", "GOODMDC",
                     "END_DECRYPTION", "CARDCTRL", "BADMDC",
                     "SC_OP_FAILURE", "SC_OP_SUCCESS",
                     "PINENTRY_LAUNCHED", "KEY_CONSIDERED"):
            pass
        else:
            Verify.handle_status(self, key, value)

class GenKey(object):
    "Handle status messages for --gen-key"
    def __init__(self, gpg):
        self.gpg = gpg
        self.type = None
        self.fingerprint = None

    def __nonzero__(self):
        if self.fingerprint: return True
        return False

    __bool__ = __nonzero__

    def __str__(self):
        return self.fingerprint or ''

    def handle_status(self, key, value):
        if key in ("WARNING", "ERROR"):  # pragma: no cover
            logger.warning('potential problem: %s: %s', key, value)
        elif key == "KEY_CREATED":
            (self.type,self.fingerprint) = value.split()
        elif key in ("PROGRESS", "GOOD_PASSPHRASE", "KEY_NOT_CREATED"):
            pass
        else:  # pragma: no cover
            logger.debug('message ignored: %s, %s', key, value)

class ExportResult(GenKey):
    """Handle status messages for --export[-secret-key].

    For now, just use an existing class to base it on - if needed, we
    can override handle_status for more specific message handling.
    """
    def handle_status(self, key, value):
        if key in ("EXPORTED", "EXPORT_RES"):
            pass
        else:
            super(ExportResult, self).handle_status(key, value)

class DeleteResult(object):
    "Handle status messages for --delete-key and --delete-secret-key"
    def __init__(self, gpg):
        self.gpg = gpg
        self.status = 'ok'

    def __str__(self):
        return self.status

    problem_reason = {
        '1': 'No such key',
        '2': 'Must delete secret key first',
        '3': 'Ambiguous specification',
    }

    def handle_status(self, key, value):
        if key == "DELETE_PROBLEM":  # pragma: no cover
            self.status = self.problem_reason.get(value,
                                                  "Unknown error: %r" % value)
        else:  # pragma: no cover
            logger.debug('message ignored: %s, %s', key, value)

    def __nonzero__(self):
        return self.status == 'ok'

    __bool__ = __nonzero__


class Sign(TextHandler):
    "Handle status messages for --sign"
    def __init__(self, gpg):
        self.gpg = gpg
        self.type = None
        self.hash_algo = None
        self.fingerprint = None
        self.status = None
        self.key_id = None
        self.username = None

    def __nonzero__(self):
        return self.fingerprint is not None

    __bool__ = __nonzero__

    def handle_status(self, key, value):
        if key in ("WARNING", "ERROR", "FAILURE"):  # pragma: no cover
            logger.warning('potential problem: %s: %s', key, value)
        elif key in ("KEYEXPIRED", "SIGEXPIRED"):  # pragma: no cover
            self.status = 'key expired'
        elif key == "KEYREVOKED":  # pragma: no cover
            self.status = 'key revoked'
        elif key == "SIG_CREATED":
            (self.type,
             algo, self.hash_algo, cls, self.timestamp, self.fingerprint
            ) = value.split()
            self.status = 'signature created'
        elif key == "USERID_HINT":  # pragma: no cover
            self.key_id, self.username = value.split(' ', 1)
        elif key == "BAD_PASSPHRASE":
            self.status = 'bad passphrase'
        elif key in ("NEED_PASSPHRASE", "GOOD_PASSPHRASE", "BEGIN_SIGNING"):
            pass
        else:  # pragma: no cover
            logger.debug('message ignored: %s, %s', key, value)

VERSION_RE = re.compile(r'gpg \(GnuPG(?:/MacGPG2)?\) (\d+(\.\d+)*)'.encode('ascii'), re.I)
HEX_DIGITS_RE = re.compile(r'[0-9a-f]+$', re.I)

class GPG(object):

    decode_errors = 'strict'

    result_map = {
        'crypt': Crypt,
        'delete': DeleteResult,
        'generate': GenKey,
        'import': ImportResult,
        'send': SendResult,
        'list': ListKeys,
        'scan': ScanKeys,
        'search': SearchKeys,
        'sign': Sign,
        'verify': Verify,
        'export': ExportResult,
    }

    "Encapsulate access to the gpg executable"
    def __init__(self, gpgbinary='gpg', gnupghome=None, verbose=False,
                 use_agent=False, keyring=None, options=None,
                 secret_keyring=None):
        """Initialize a GPG process wrapper.  Options are:

        gpgbinary -- full pathname for GPG binary.

        gnupghome -- full pathname to where we can find the public and
        private keyrings.  Default is whatever gpg defaults to.
        keyring -- name of alternative keyring file to use, or list of such
        keyrings. If specified, the default keyring is not used.
        options =-- a list of additional options to pass to the GPG binary.
        secret_keyring -- name of alternative secret keyring file to use, or
        list of such keyrings.
        """
        self.gpgbinary = gpgbinary
        self.gnupghome = gnupghome
        if keyring:
            # Allow passing a string or another iterable. Make it uniformly
            # a list of keyring filenames
            if isinstance(keyring, string_types):
                keyring = [keyring]
        self.keyring = keyring
        if secret_keyring:
            # Allow passing a string or another iterable. Make it uniformly
            # a list of keyring filenames
            if isinstance(secret_keyring, string_types):
                secret_keyring = [secret_keyring]
        self.secret_keyring = secret_keyring
        self.verbose = verbose
        self.use_agent = use_agent
        if isinstance(options, str):  # pragma: no cover
            options = [options]
        self.options = options
        self.on_data = None  # or a callable - will be called with data chunks
        # Changed in 0.3.7 to use Latin-1 encoding rather than
        # locale.getpreferredencoding falling back to sys.stdin.encoding
        # falling back to utf-8, because gpg itself uses latin-1 as the default
        # encoding.
        self.encoding = 'latin-1'
        if gnupghome and not os.path.isdir(self.gnupghome):
            os.makedirs(self.gnupghome,0x1C0)
        try:
            p = self._open_subprocess(["--version"])
        except OSError:
            msg = 'Unable to run gpg (%s) - it may not be available.' % self.gpgbinary
            logger.exception(msg)
            raise OSError(msg)
        result = self.result_map['verify'](self) # any result will do for this
        self._collect_output(p, result, stdin=p.stdin)
        if p.returncode != 0:  # pragma: no cover
            raise ValueError("Error invoking gpg: %s: %s" % (p.returncode,
                                                             result.stderr))
        m = VERSION_RE.match(result.data)
        if not m:  # pragma: no cover
            self.version = None
        else:
            dot = '.'.encode('ascii')
            self.version = tuple([int(s) for s in m.groups()[0].split(dot)])

    def make_args(self, args, passphrase):
        """
        Make a list of command line elements for GPG. The value of ``args``
        will be appended. The ``passphrase`` argument needs to be True if
        a passphrase will be sent to GPG, else False.
        """
        cmd = [self.gpgbinary, '--status-fd', '2', '--no-tty', '--no-verbose']
        if 'DEBUG_IPC' in os.environ:
            cmd.extend(['--debug', 'ipc'])
        if passphrase and hasattr(self, 'version'):
            if self.version >= (2, 1):
                cmd[1:1] = ['--pinentry-mode', 'loopback']
        cmd.extend(['--fixed-list-mode', '--batch', '--with-colons'])
        if self.gnupghome:
            cmd.extend(['--homedir',  no_quote(self.gnupghome)])
        if self.keyring:
            cmd.append('--no-default-keyring')
            for fn in self.keyring:
                cmd.extend(['--keyring', no_quote(fn)])
        if self.secret_keyring:
            for fn in self.secret_keyring:
                cmd.extend(['--secret-keyring', no_quote(fn)])
        if passphrase:
            cmd.extend(['--passphrase-fd', '0'])
        if self.use_agent:  # pragma: no cover
            cmd.append('--use-agent')
        if self.options:
            cmd.extend(self.options)
        cmd.extend(args)
        return cmd

    def _open_subprocess(self, args, passphrase=False):
        # Internal method: open a pipe to a GPG subprocess and return
        # the file objects for communicating with it.

        # def debug_print(cmd):
            # result = []
            # for c in cmd:
                # if ' ' not in c:
                    # result.append(c)
                # else:
                    # if '"' not in c:
                        # result.append('"%s"' % c)
                    # elif "'" not in c:
                        # result.append("'%s'" % c)
                    # else:
                        # result.append(c)  # give up
            # return ' '.join(cmd)
        from subprocess import list2cmdline as debug_print

        cmd = self.make_args(args, passphrase)
        if self.verbose:  # pragma: no cover
            print(debug_print(cmd))
        if not STARTUPINFO:
            si = None
        else:  # pragma: no cover
            si = STARTUPINFO()
            si.dwFlags = STARTF_USESHOWWINDOW
            si.wShowWindow = SW_HIDE
        result = Popen(cmd, shell=False, stdin=PIPE, stdout=PIPE, stderr=PIPE,
                       startupinfo=si)
        logger.debug("%s: %s", result.pid, debug_print(cmd))
        return result

    def _read_response(self, stream, result):
        # Internal method: reads all the stderr output from GPG, taking notice
        # only of lines that begin with the magic [GNUPG:] prefix.
        #
        # Calls methods on the response object for each valid token found,
        # with the arg being the remainder of the status line.
        lines = []
        while True:
            line = stream.readline()
            if len(line) == 0:
                break
            lines.append(line)
            line = line.rstrip()
            if self.verbose:  # pragma: no cover
                print(line)
            logger.debug("%s", line)
            if line[0:9] == '[GNUPG:] ':
                # Chop off the prefix
                line = line[9:]
                L = line.split(None, 1)
                keyword = L[0]
                if len(L) > 1:
                    value = L[1]
                else:
                    value = ""
                result.handle_status(keyword, value)
        result.stderr = ''.join(lines)

    def _read_data(self, stream, result, on_data=None):
        # Read the contents of the file from GPG's stdout
        chunks = []
        while True:
            data = stream.read(1024)
            if len(data) == 0:
                break
            logger.debug("chunk: %r" % data[:256])
            chunks.append(data)
            if on_data:
                on_data(data)
        if _py3k:
            # Join using b'' or '', as appropriate
            result.data = type(data)().join(chunks)
        else:
            result.data = ''.join(chunks)

    def _collect_output(self, process, result, writer=None, stdin=None):
        """
        Drain the subprocesses output streams, writing the collected output
        to the result. If a writer thread (writing to the subprocess) is given,
        make sure it's joined before returning. If a stdin stream is given,
        close it before returning.
        """
        stderr = codecs.getreader(self.encoding)(process.stderr)
        rr = threading.Thread(target=self._read_response, args=(stderr, result))
        rr.setDaemon(True)
        logger.debug('stderr reader: %r', rr)
        rr.start()

        stdout = process.stdout
        dr = threading.Thread(target=self._read_data, args=(stdout, result, self.on_data))
        dr.setDaemon(True)
        logger.debug('stdout reader: %r', dr)
        dr.start()

        dr.join()
        rr.join()
        if writer is not None:
            writer.join()
        process.wait()
        if stdin is not None:
            try:
                stdin.close()
            except IOError:  # pragma: no cover
                pass
        stderr.close()
        stdout.close()

    def _handle_io(self, args, fileobj, result, passphrase=None, binary=False):
        "Handle a call to GPG - pass input data, collect output data"
        # Handle a basic data call - pass data to GPG, handle the output
        # including status information. Garbage In, Garbage Out :)
        p = self._open_subprocess(args, passphrase is not None)
        if not binary:  # pragma: no cover
            stdin = codecs.getwriter(self.encoding)(p.stdin)
        else:
            stdin = p.stdin
        if passphrase:
            _write_passphrase(stdin, passphrase, self.encoding)
        writer = _threaded_copy_data(fileobj, stdin)
        self._collect_output(p, result, writer, stdin)
        return result

    #
    # SIGNATURE METHODS
    #
    def sign(self, message, **kwargs):
        """sign message"""
        f = _make_binary_stream(message, self.encoding)
        result = self.sign_file(f, **kwargs)
        f.close()
        return result

    def set_output_without_confirmation(self, args, output):
        "If writing to a file which exists, avoid a confirmation message."
        if os.path.exists(output):
            # We need to avoid an overwrite confirmation message
            args.extend(['--yes'])
        args.extend(['--output', no_quote(output)])

    def sign_file(self, file, keyid=None, passphrase=None, clearsign=True,
                  detach=False, binary=False, output=None, extra_args=None):
        """sign file"""
        logger.debug("sign_file: %s", file)
        if binary:  # pragma: no cover
            args = ['-s']
        else:
            args = ['-sa']
        # You can't specify detach-sign and clearsign together: gpg ignores
        # the detach-sign in that case.
        if detach:
            args.append("--detach-sign")
        elif clearsign:
            args.append("--clearsign")
        if keyid:
            args.extend(['--default-key', no_quote(keyid)])
        if output:  # write the output to a file with the specified name
            self.set_output_without_confirmation(args, output)

        if extra_args:
            args.extend(extra_args)
        result = self.result_map['sign'](self)
        #We could use _handle_io here except for the fact that if the
        #passphrase is bad, gpg bails and you can't write the message.
        p = self._open_subprocess(args, passphrase is not None)
        try:
            stdin = p.stdin
            if passphrase:
                _write_passphrase(stdin, passphrase, self.encoding)
            writer = _threaded_copy_data(file, stdin)
        except IOError:  # pragma: no cover
            logging.exception("error writing message")
            writer = None
        self._collect_output(p, result, writer, stdin)
        return result

    def verify(self, data, **kwargs):
        """Verify the signature on the contents of the string 'data'

        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome="keys")
        >>> input = gpg.gen_key_input(passphrase='foo')
        >>> key = gpg.gen_key(input)
        >>> assert key
        >>> sig = gpg.sign('hello',keyid=key.fingerprint,passphrase='bar')
        >>> assert not sig
        >>> sig = gpg.sign('hello',keyid=key.fingerprint,passphrase='foo')
        >>> assert sig
        >>> verify = gpg.verify(sig.data)
        >>> assert verify

        """
        f = _make_binary_stream(data, self.encoding)
        result = self.verify_file(f, **kwargs)
        f.close()
        return result

    def verify_file(self, file, data_filename=None, close_file=True, extra_args=None):
        "Verify the signature on the contents of the file-like object 'file'"
        logger.debug('verify_file: %r, %r', file, data_filename)
        result = self.result_map['verify'](self)
        args = ['--verify']
        if extra_args:
            args.extend(extra_args)
        if data_filename is None:
            self._handle_io(args, file, result, binary=True)
        else:
            logger.debug('Handling detached verification')
            import tempfile
            fd, fn = tempfile.mkstemp(prefix='pygpg')
            s = file.read()
            if close_file:
                file.close()
            logger.debug('Wrote to temp file: %r', s)
            os.write(fd, s)
            os.close(fd)
            args.append(no_quote(fn))
            args.append(no_quote(data_filename))
            try:
                p = self._open_subprocess(args)
                self._collect_output(p, result, stdin=p.stdin)
            finally:
                os.unlink(fn)
        return result

    def verify_data(self, sig_filename, data, extra_args=None):
        "Verify the signature in sig_filename against data in memory"
        logger.debug('verify_data: %r, %r ...', sig_filename, data[:16])
        result = self.result_map['verify'](self)
        args = ['--verify']
        if extra_args:
            args.extend(extra_args)
        args.extend([no_quote(sig_filename), '-'])
        stream = _make_memory_stream(data)
        self._handle_io(args, stream, result, binary=True)
        return result

    #
    # KEY MANAGEMENT
    #

    def import_keys(self, key_data):
        """
        Import the key_data into our keyring.
        """
        result = self.result_map['import'](self)
        logger.debug('import_keys: %r', key_data[:256])
        data = _make_binary_stream(key_data, self.encoding)
        self._handle_io(['--import'], data, result, binary=True)
        logger.debug('import_keys result: %r', result.__dict__)
        data.close()
        return result

    def recv_keys(self, keyserver, *keyids):
        """Import a key from a keyserver

        >>> import shutil
        >>> shutil.rmtree("keys", ignore_errors=True)
        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome="keys")
        >>> os.chmod('keys', 0x1C0)
        >>> result = gpg.recv_keys('pgp.mit.edu', '92905378')
        >>> assert result

        """
        result = self.result_map['import'](self)
        logger.debug('recv_keys: %r', keyids)
        data = _make_binary_stream("", self.encoding)
        #data = ""
        args = ['--keyserver', no_quote(keyserver), '--recv-keys']
        args.extend([no_quote(k) for k in keyids])
        self._handle_io(args, data, result, binary=True)
        logger.debug('recv_keys result: %r', result.__dict__)
        data.close()
        return result

    def send_keys(self, keyserver, *keyids):
        """Send a key to a keyserver.

        Note: it's not practical to test this function without sending
        arbitrary data to live keyservers.
        """
        result = self.result_map['send'](self)
        logger.debug('send_keys: %r', keyids)
        data = _make_binary_stream('', self.encoding)
        #data = ""
        args = ['--keyserver', no_quote(keyserver), '--send-keys']
        args.extend([no_quote(k) for k in keyids])
        self._handle_io(args, data, result, binary=True)
        logger.debug('send_keys result: %r', result.__dict__)
        data.close()
        return result

    def delete_keys(self, fingerprints, secret=False, passphrase=None,
                    expect_passphrase=True):
        """
        Delete the indicated keys.

        Since GnuPG 2.1, you can't delete secret keys without providing a
        passphrase. However, if you're expecting the passphrase to go to gpg
        via pinentry, you should specify expect_passphrase=False. (It's only
        checked for GnuPG >= 2.1).
        """
        which='key'
        if secret:  # pragma: no cover
            if (self.version >= (2, 1) and passphrase is None and
                expect_passphrase):
                raise ValueError('For GnuPG >= 2.1, deleting secret keys '
                                 'needs a passphrase to be provided')
            which='secret-key'
        if _is_sequence(fingerprints):  # pragma: no cover
            fingerprints = [no_quote(s) for s in fingerprints]
        else:
            fingerprints = [no_quote(fingerprints)]
        args = ['--delete-%s' % which]
        args.extend(fingerprints)
        result = self.result_map['delete'](self)
        if not secret or self.version < (2, 1):
            p = self._open_subprocess(args)
            self._collect_output(p, result, stdin=p.stdin)
        else:
            # Need to send in a passphrase.
            f = _make_binary_stream('', self.encoding)
            try:
                self._handle_io(args, f, result, passphrase=passphrase,
                                binary=True)
            finally:
                f.close()
        return result

    def export_keys(self, keyids, secret=False, armor=True, minimal=False,
                    passphrase=None, expect_passphrase=True):
        """
        Export the indicated keys. A 'keyid' is anything gpg accepts.

        Since GnuPG 2.1, you can't export secret keys without providing a
        passphrase. However, if you're expecting the passphrase to go to gpg
        via pinentry, you should specify expect_passphrase=False. (It's only
        checked for GnuPG >= 2.1).
        """

        which=''
        if secret:
            which='-secret-key'
            if (self.version >= (2, 1) and passphrase is None and
                expect_passphrase):
                raise ValueError('For GnuPG >= 2.1, exporting secret keys '
                                 'needs a passphrase to be provided')
        if _is_sequence(keyids):
            keyids = [no_quote(k) for k in keyids]
        else:
            keyids = [no_quote(keyids)]
        args = ['--export%s' % which]
        if armor:
            args.append('--armor')
        if minimal:  # pragma: no cover
            args.extend(['--export-options','export-minimal'])
        args.extend(keyids)
        # gpg --export produces no status-fd output; stdout will be
        # empty in case of failure
        #stdout, stderr = p.communicate()
        result = self.result_map['export'](self)
        if not secret or self.version < (2, 1):
            p = self._open_subprocess(args)
            self._collect_output(p, result, stdin=p.stdin)
        else:
            # Need to send in a passphrase.
            f = _make_binary_stream('', self.encoding)
            try:
                self._handle_io(args, f, result, passphrase=passphrase,
                                binary=True)
            finally:
                f.close()
        logger.debug('export_keys result: %r', result.data)
        # Issue #49: Return bytes if armor not specified, else text
        result = result.data
        if armor:
            result = result.decode(self.encoding, self.decode_errors)
        return result

    def _get_list_output(self, p, kind):
        # Get the response information
        result = self.result_map[kind](self)
        self._collect_output(p, result, stdin=p.stdin)
        lines = result.data.decode(self.encoding,
                                   self.decode_errors).splitlines()
        valid_keywords = 'pub uid sec fpr sub ssb sig'.split()
        for line in lines:
            if self.verbose:  # pragma: no cover
                print(line)
            logger.debug("line: %r", line.rstrip())
            if not line:  # pragma: no cover
                break
            L = line.strip().split(':')
            if not L:  # pragma: no cover
                continue
            keyword = L[0]
            if keyword in valid_keywords:
                getattr(result, keyword)(L)
        return result

    def list_keys(self, secret=False, keys=None, sigs=False):
        """ list the keys currently in the keyring

        >>> import shutil
        >>> shutil.rmtree("keys", ignore_errors=True)
        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome="keys")
        >>> input = gpg.gen_key_input(passphrase='foo')
        >>> result = gpg.gen_key(input)
        >>> fp1 = result.fingerprint
        >>> result = gpg.gen_key(input)
        >>> fp2 = result.fingerprint
        >>> pubkeys = gpg.list_keys()
        >>> assert fp1 in pubkeys.fingerprints
        >>> assert fp2 in pubkeys.fingerprints

        """

        if sigs:
            which = 'sigs'
        else:            which='keys'
        if secret:
            which='secret-keys'
        args = ['--list-%s' % which,
                '--fingerprint', '--fingerprint'] # get subkey FPs, too
        if keys:
            if isinstance(keys, string_types):
                keys = [keys]
            args.extend(keys)
        p = self._open_subprocess(args)
        return self._get_list_output(p, 'list')

    def scan_keys(self, filename):
        """
        List details of an ascii armored or binary key file
        without first importing it to the local keyring.

        The function achieves this on modern GnuPG by running:

        $ gpg --dry-run --import-options import-show --import

        On older versions, it does the *much* riskier:

        $ gpg --with-fingerprint --with-colons filename
        """
        if self.version >= (2, 1):
            args = ['--dry-run', '--import-options', 'import-show', '--import']
        else:
            logger.warning('Trying to list packets, but if the file is not a '
                           'keyring, might accidentally decrypt')
            args = ['--with-fingerprint', '--with-colons', '--fixed-list-mode']
        args.append(no_quote(filename))
        p = self._open_subprocess(args)
        return self._get_list_output(p, 'scan')

    def search_keys(self, query, keyserver='pgp.mit.edu'):
        """ search keyserver by query (using --search-keys option)

        >>> import shutil
        >>> shutil.rmtree('keys', ignore_errors=True)
        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome='keys')
        >>> os.chmod('keys', 0x1C0)
        >>> result = gpg.search_keys('<vinay_sajip@hotmail.com>')
        >>> assert result, 'Failed using default keyserver'
        >>> #keyserver = 'keyserver.ubuntu.com'
        >>> #result = gpg.search_keys('<vinay_sajip@hotmail.com>', keyserver)
        >>> #assert result, 'Failed using keyserver.ubuntu.com'

        """
        query = query.strip()
        if HEX_DIGITS_RE.match(query):
            query = '0x' + query
        args = ['--fingerprint',
                '--keyserver', no_quote(keyserver), '--search-keys',
                no_quote(query)]
        p = self._open_subprocess(args)

        # Get the response information
        result = self.result_map['search'](self)
        self._collect_output(p, result, stdin=p.stdin)
        lines = result.data.decode(self.encoding,
                                   self.decode_errors).splitlines()
        valid_keywords = ['pub', 'uid']
        for line in lines:
            if self.verbose:  # pragma: no cover
                print(line)
            logger.debug('line: %r', line.rstrip())
            if not line:    # sometimes get blank lines on Windows
                continue
            L = line.strip().split(':')
            if not L:  # pragma: no cover
                continue
            keyword = L[0]
            if keyword in valid_keywords:
                getattr(result, keyword)(L)
        return result

    def gen_key(self, input):
        """Generate a key; you might use gen_key_input() to create the
        control input.

        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome="keys")
        >>> input = gpg.gen_key_input(passphrase='foo')
        >>> result = gpg.gen_key(input)
        >>> assert result
        >>> result = gpg.gen_key('foo')
        >>> assert not result

        """
        args = ["--gen-key"]
        result = self.result_map['generate'](self)
        f = _make_binary_stream(input, self.encoding)
        self._handle_io(args, f, result, binary=True)
        f.close()
        return result

    def gen_key_input(self, **kwargs):
        """
        Generate --gen-key input per gpg doc/DETAILS
        """
        parms = {}
        for key, val in list(kwargs.items()):
            key = key.replace('_','-').title()
            if str(val).strip():    # skip empty strings
                parms[key] = val
        parms.setdefault('Key-Type','RSA')
        parms.setdefault('Key-Length',2048)
        parms.setdefault('Name-Real', "Autogenerated Key")
        logname = (os.environ.get('LOGNAME') or os.environ.get('USERNAME') or
                   'unspecified')
        hostname = socket.gethostname()
        parms.setdefault('Name-Email', "%s@%s" % (logname.replace(' ', '_'),
                                                  hostname))
        out = "Key-Type: %s\n" % parms.pop('Key-Type')
        for key, val in list(parms.items()):
            out += "%s: %s\n" % (key, val)
        out += "%commit\n"
        return out

        # Key-Type: RSA
        # Key-Length: 1024
        # Name-Real: ISdlink Server on %s
        # Name-Comment: Created by %s
        # Name-Email: isdlink@%s
        # Expire-Date: 0
        # %commit
        #
        #
        # Key-Type: DSA
        # Key-Length: 1024
        # Subkey-Type: ELG-E
        # Subkey-Length: 1024
        # Name-Real: Joe Tester
        # Name-Comment: with stupid passphrase
        # Name-Email: joe@foo.bar
        # Expire-Date: 0
        # Passphrase: abc
        # %pubring foo.pub
        # %secring foo.sec
        # %commit

    #
    # ENCRYPTION
    #
    def encrypt_file(self, file, recipients, sign=None,
            always_trust=False, passphrase=None,
            armor=True, output=None, symmetric=False, extra_args=None):
        "Encrypt the message read from the file-like object 'file'"
        args = ['--encrypt']
        if symmetric:
            # can't be False or None - could be True or a cipher algo value
            # such as AES256
            args = ['--symmetric']
            if symmetric is not True:
                args.extend(['--cipher-algo', no_quote(symmetric)])
            # else use the default, currently CAST5
        else:
            if not recipients:
                raise ValueError('No recipients specified with asymmetric '
                                 'encryption')
            if not _is_sequence(recipients):
                recipients = (recipients,)
            for recipient in recipients:
                args.extend(['--recipient', no_quote(recipient)])
        if armor:   # create ascii-armored output - False for binary output
            args.append('--armor')
        if output:  # write the output to a file with the specified name
            self.set_output_without_confirmation(args, output)
        if sign is True:  # pragma: no cover
            args.append('--sign')
        elif sign:  # pragma: no cover
            args.extend(['--sign', '--default-key', no_quote(sign)])
        if always_trust:  # pragma: no cover
            args.append('--always-trust')
        if extra_args:
            args.extend(extra_args)
        result = self.result_map['crypt'](self)
        self._handle_io(args, file, result, passphrase=passphrase, binary=True)
        logger.debug('encrypt result: %r', result.data)
        return result

    def encrypt(self, data, recipients, **kwargs):
        """Encrypt the message contained in the string 'data'

        >>> import shutil
        >>> if os.path.exists("keys"):
        ...     shutil.rmtree("keys", ignore_errors=True)
        >>> GPGBINARY = os.environ.get('GPGBINARY', 'gpg')
        >>> gpg = GPG(gpgbinary=GPGBINARY, gnupghome="keys")
        >>> input = gpg.gen_key_input(name_email='user1@test', passphrase='pp1')
        >>> result = gpg.gen_key(input)
        >>> fp1 = result.fingerprint
        >>> input = gpg.gen_key_input(name_email='user2@test', passphrase='pp2')
        >>> result = gpg.gen_key(input)
        >>> fp2 = result.fingerprint
        >>> result = gpg.encrypt("hello",fp2)
        >>> message = str(result)
        >>> assert message != 'hello'
        >>> result = gpg.decrypt(message, passphrase='pp2')
        >>> assert result
        >>> str(result)
        'hello'
        >>> result = gpg.encrypt("hello again", fp1)
        >>> message = str(result)
        >>> result = gpg.decrypt(message, passphrase='bar')
        >>> result.status in ('decryption failed', 'bad passphrase')
        True
        >>> assert not result
        >>> result = gpg.decrypt(message, passphrase='pp1')
        >>> result.status == 'decryption ok'
        True
        >>> str(result)
        'hello again'
        >>> result = gpg.encrypt("signed hello", fp2, sign=fp1, passphrase='pp1')
        >>> result.status == 'encryption ok'
        True
        >>> message = str(result)
        >>> result = gpg.decrypt(message, passphrase='pp2')
        >>> result.status == 'decryption ok'
        True
        >>> assert result.fingerprint == fp1

        """
        data = _make_binary_stream(data, self.encoding)
        result = self.encrypt_file(data, recipients, **kwargs)
        data.close()
        return result

    def decrypt(self, message, **kwargs):
        data = _make_binary_stream(message, self.encoding)
        result = self.decrypt_file(data, **kwargs)
        data.close()
        return result

    def decrypt_file(self, file, always_trust=False, passphrase=None,
                     output=None, extra_args=None):
        args = ["--decrypt"]
        if output:  # write the output to a file with the specified name
            self.set_output_without_confirmation(args, output)
        if always_trust:  # pragma: no cover
            args.append("--always-trust")
        if extra_args:
            args.extend(extra_args)
        result = self.result_map['crypt'](self)
        self._handle_io(args, file, result, passphrase, binary=True)
        logger.debug('decrypt result: %r', result.data)
        return result

    def trust_keys(self, fingerprints, trustlevel):
        levels = Verify.TRUST_LEVELS
        if trustlevel not in levels:
            poss = ', '.join(sorted(levels))
            raise ValueError('Invalid trust level: "%s" (must be one of %s)' %
                             (trustlevel, poss))
        trustlevel = levels[trustlevel] + 2
        import tempfile
        try:
            fd, fn = tempfile.mkstemp()
            lines = []
            if isinstance(fingerprints, string_types):
                fingerprints = [fingerprints]
            for f in fingerprints:
                lines.append('%s:%s:' % (f, trustlevel))
            # The trailing newline is required!
            s = os.linesep.join(lines) + os.linesep
            logger.debug('writing ownertrust info: %s', s);
            os.write(fd, s.encode(self.encoding))
            os.close(fd)
            result = self.result_map['delete'](self)
            p = self._open_subprocess(['--import-ownertrust', fn])
            self._collect_output(p, result, stdin=p.stdin)
        finally:
            os.remove(fn)
        return result