#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""*********************************************************************
* Edward is free software: you can redistribute it and/or modify *
* it under the terms of the GNU Affero Public License as published by *
* the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* Edward 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 Affero Public License for more details. *
* *
* You should have received a copy of the GNU Affero Public License *
* along with Edward. If not, see . *
* *
* Copyright (C) 2014-2015 Andrew Engelbrecht (AGPLv3+) *
* Copyright (C) 2014 Josh Drake (AGPLv3+) *
* Copyright (C) 2014 Lisa Marie Maginnis (AGPLv3+) *
* Copyright (C) 2009-2015 Tails developers ( GPLv3+) *
* Copyright (C) 2009 W. Trevor King ( GPLv2+) *
* *
* Special thanks to Josh Drake for writing the original edward bot! :) *
* *
************************************************************************
Code sourced from these projects:
* http://agpl.fsf.org/emailselfdefense.fsf.org/edward/CURRENT/edward.tar.gz
* https://git-tails.immerda.ch/whisperback/tree/whisperBack/encryption.py?h=feature/python3
* http://www.physics.drexel.edu/~wking/code/python/send_pgp_mime
"""
import sys
import gpgme
import re
import io
import os
import importlib
import email.parser
import email.message
import email.encoders
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication
from email.mime.nonmultipart import MIMENonMultipart
import edward_config
langs = ["an", "de", "el", "en", "fr", "ja", "pt-br", "ro", "ru", "tr"]
match_types = [('clearsign',
'-----BEGIN PGP SIGNED MESSAGE-----.*?-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----'),
('message',
'-----BEGIN PGP MESSAGE-----.*?-----END PGP MESSAGE-----'),
('pubkey',
'-----BEGIN PGP PUBLIC KEY BLOCK-----.*?-----END PGP PUBLIC KEY BLOCK-----'),
('detachedsig',
'-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----')]
class EddyMsg (object):
def __init__(self):
self.multipart = False
self.subparts = []
self.charset = None
self.payload_bytes = None
self.payload_pieces = []
self.filename = None
self.content_type = None
self.description_list = None
class PayloadPiece (object):
def __init__(self):
self.piece_type = None
self.string = None
self.gpg_data = None
class GPGData (object):
def __init__(self):
self.decrypted = False
self.plainobj = None
self.sigs = []
self.keys = []
class ReplyInfo (object):
def __init__(self):
self.replies = None
self.target_key = None
self.fallback_target_key = None
self.msg_to_quote = ""
self.success_decrypt = False
self.failed_decrypt = False
self.public_key_received = False
self.no_public_key = False
self.sig_success = False
self.sig_failure = False
def main ():
handle_args()
gpgme_ctx = get_gpg_context(edward_config.gnupghome,
edward_config.sign_with_key)
email_text = sys.stdin.read()
email_struct = parse_pgp_mime(email_text, gpgme_ctx)
email_to, email_from, email_subject = email_to_from_subject(email_text)
lang = import_lang(email_to)
replyinfo_obj = ReplyInfo()
replyinfo_obj.replies = lang.replies
prepare_for_reply(email_struct, replyinfo_obj)
encrypt_to_key = get_key_from_fp(replyinfo_obj, gpgme_ctx)
reply_plaintext = write_reply(replyinfo_obj)
# TODO error handling for missing keys and setting .no_public_key
reply_mime = generate_encrypted_mime(reply_plaintext, email_from, \
email_subject, encrypt_to_key,
gpgme_ctx)
print(reply_mime)
def get_gpg_context (gnupghome, sign_with_key_fp):
os.environ['GNUPGHOME'] = gnupghome
gpgme_ctx = gpgme.Context()
gpgme_ctx.armor = True
try:
sign_with_key = gpgme_ctx.get_key(sign_with_key_fp)
except:
error("unable to load signing key. is the gnupghome "
+ "and signing key properly set in the edward_config.py?")
exit(1)
gpgme_ctx.signers = [sign_with_key]
return gpgme_ctx
def parse_pgp_mime (email_text, gpgme_ctx):
email_struct = email.parser.Parser().parsestr(email_text)
eddymsg_obj = parse_mime(email_struct)
split_payloads(eddymsg_obj)
gpg_on_payloads(eddymsg_obj, gpgme_ctx)
return eddymsg_obj
def parse_mime(msg_struct):
eddymsg_obj = EddyMsg()
if msg_struct.is_multipart() == True:
payloads = msg_struct.get_payload()
eddymsg_obj.multipart = True
eddymsg_obj.subparts = list(map(parse_mime, payloads))
else:
eddymsg_obj = get_subpart_data(msg_struct)
return eddymsg_obj
def scan_and_split (payload_piece, match_type, pattern):
# don't try to re-split pieces containing gpg data
if payload_piece.piece_type != "text":
return [payload_piece]
flags = re.DOTALL | re.MULTILINE
matches = re.search("(?P.*?)(?P" + pattern +
")(?P.*)", payload_piece.string, flags=flags)
if matches == None:
pieces = [payload_piece]
else:
beginning = PayloadPiece()
beginning.string = matches.group('beginning')
beginning.piece_type = payload_piece.piece_type
match = PayloadPiece()
match.string = matches.group('match')
match.piece_type = match_type
rest = PayloadPiece()
rest.string = matches.group('rest')
rest.piece_type = payload_piece.piece_type
more_pieces = scan_and_split(rest, match_type, pattern)
pieces = [beginning, match ] + more_pieces
return pieces
def get_subpart_data (part):
obj = EddyMsg()
obj.charset = part.get_content_charset()
obj.payload_bytes = part.get_payload(decode=True)
obj.filename = part.get_filename()
obj.content_type = part.get_content_type()
obj.description_list = part['content-description']
# your guess is as good as a-myy-ee-ine...
if obj.charset == None:
obj.charset = 'utf-8'
if obj.payload_bytes != None:
try:
payload = PayloadPiece()
payload.string = obj.payload_bytes.decode(obj.charset)
payload.piece_type = 'text'
obj.payload_pieces = [payload]
except UnicodeDecodeError:
pass
return obj
def do_to_eddys_pieces (function_to_do, eddymsg_obj, data):
if eddymsg_obj.multipart == True:
for sub in eddymsg_obj.subparts:
do_to_eddys_pieces(function_to_do, sub, data)
else:
function_to_do(eddymsg_obj, data)
def split_payloads (eddymsg_obj):
for match_type in match_types:
do_to_eddys_pieces(split_payload_pieces, eddymsg_obj, match_type)
def split_payload_pieces (eddymsg_obj, match_type):
(match_name, pattern) = match_type
new_pieces_list = []
for piece in eddymsg_obj.payload_pieces:
new_pieces_list += scan_and_split(piece, match_name, pattern)
eddymsg_obj.payload_pieces = new_pieces_list
def gpg_on_payloads (eddymsg_obj, gpgme_ctx, prev_parts=[]):
if eddymsg_obj.multipart == True:
prev_parts=[]
for sub in eddymsg_obj.subparts:
gpg_on_payloads (sub, gpgme_ctx, prev_parts)
prev_parts += [sub]
return
for piece in eddymsg_obj.payload_pieces:
if piece.piece_type == "text":
# don't transform the plaintext.
pass
elif piece.piece_type == "message":
(plaintext, sigs) = decrypt_block(piece.string, gpgme_ctx)
if plaintext:
piece.gpg_data = GPGData()
piece.gpg_data.decrypted = True
piece.gpg_data.sigs = sigs
# recurse!
piece.gpg_data.plainobj = parse_pgp_mime(plaintext, gpgme_ctx)
elif piece.piece_type == "pubkey":
key_fps = add_gpg_key(piece.string, gpgme_ctx)
if key_fps != []:
piece.gpg_data = GPGData()
piece.gpg_data.keys = key_fps
elif piece.piece_type == "clearsign":
(plaintext, sig_fps) = verify_clear_signature(piece.string, gpgme_ctx)
if sig_fps != []:
piece.gpg_data = GPGData()
piece.gpg_data.sigs = sig_fps
piece.gpg_data.plainobj = parse_pgp_mime(plaintext, gpgme_ctx)
elif piece.piece_type == "detachedsig":
for prev in prev_parts:
payload_bytes = prev.payload_bytes
sig_fps = verify_detached_signature(piece.string, payload_bytes, gpgme_ctx)
if sig_fps != []:
piece.gpg_data = GPGData()
piece.gpg_data.sigs = sig_fps
piece.gpg_data.plainobj = prev
break
else:
pass
def prepare_for_reply (eddymsg_obj, replyinfo_obj):
do_to_eddys_pieces(prepare_for_reply_pieces, eddymsg_obj, replyinfo_obj)
def prepare_for_reply_pieces (eddymsg_obj, replyinfo_obj):
for piece in eddymsg_obj.payload_pieces:
if piece.piece_type == "text":
# don't quote the plaintext part.
pass
elif piece.piece_type == "message":
if piece.gpg_data == None:
replyinfo_obj.failed_decrypt = True
else:
replyinfo_obj.success_decrypt = True
if replyinfo_obj.target_key != None:
continue
if piece.gpg_data.sigs != []:
replyinfo_obj.target_key = piece.gpg_data.sigs[0]
replyinfo_obj.msg_to_quote = flatten_payloads(piece.gpg_data.plainobj)
# to catch public keys in encrypted blocks
prepare_for_reply(piece.gpg_data.plainobj, replyinfo_obj)
elif piece.piece_type == "pubkey":
if piece.gpg_data == None:
replyinfo_obj.no_public_key = True
else:
replyinfo_obj.public_key_received = True
elif (piece.piece_type == "clearsign") \
or (piece.piece_type == "detachedsig"):
if piece.gpg_data == None:
replyinfo_obj.sig_failure = True
else:
replyinfo_obj.sig_success = True
if replyinfo_obj.target_key == None:
replyinfo_obj.fallback_target_key = piece.gpg_data.sigs[0]
def flatten_payloads (eddymsg_obj):
flat_string = ""
if eddymsg_obj == None:
return ""
if eddymsg_obj.multipart == True:
for sub in eddymsg_obj.subparts:
flat_string += flatten_payloads (sub)
return flat_string
# todo: don't include nested decrypted messages.
for piece in eddymsg_obj.payload_pieces:
if piece.piece_type == "text":
flat_string += piece.string
elif piece.piece_type == "message":
flat_string += flatten_payloads(piece.plainobj)
elif ((piece.piece_type == "clearsign") \
or (piece.piece_type == "detachedsig")) \
and (piece.gpg_data != None):
flat_string += flatten_payloads (piece.gpg_data.plainobj)
return flat_string
def get_key_from_fp (replyinfo_obj, gpgme_ctx):
if replyinfo_obj.target_key == None:
replyinfo_obj.target_key = replyinfo_obj.fallback_target_key
if replyinfo_obj.target_key != None:
try:
encrypt_to_key = gpgme_ctx.get_key(replyinfo_obj.target_key)
return encrypt_to_key
except:
pass
# no available key to use
replyinfo_obj.target_key = None
replyinfo_obj.fallback_target_key = None
replyinfo_obj.no_public_key = True
replyinfo_obj.public_key_received = False
return None
def write_reply (replyinfo_obj):
reply_plain = ""
if replyinfo_obj.success_decrypt == True:
reply_plain += replyinfo_obj.replies['success_decrypt']
if replyinfo_obj.no_public_key == False:
quoted_text = email_quote_text(replyinfo_obj.msg_to_quote)
reply_plain += quoted_text
elif replyinfo_obj.failed_decrypt == True:
reply_plain += replyinfo_obj.replies['failed_decrypt']
if replyinfo_obj.sig_success == True:
reply_plain += "\n\n"
reply_plain += replyinfo_obj.replies['sig_success']
elif replyinfo_obj.sig_failure == True:
reply_plain += "\n\n"
reply_plain += replyinfo_obj.replies['sig_failure']
if replyinfo_obj.public_key_received == True:
reply_plain += "\n\n"
reply_plain += replyinfo_obj.replies['public_key_received']
elif replyinfo_obj.no_public_key == True:
reply_plain += "\n\n"
reply_plain += replyinfo_obj.replies['no_public_key']
reply_plain += "\n\n"
reply_plain += replyinfo_obj.replies['signature']
return reply_plain
def add_gpg_key (key_block, gpgme_ctx):
fp = io.BytesIO(key_block.encode('ascii'))
result = gpgme_ctx.import_(fp)
imports = result.imports
key_fingerprints = []
if imports != []:
for import_ in imports:
fingerprint = import_[0]
key_fingerprints += [fingerprint]
debug("added gpg key: " + fingerprint)
return key_fingerprints
def verify_clear_signature (sig_block, gpgme_ctx):
# FIXME: this might require the un-decoded bytes
# or the correct re-encoding with the carset of the mime part.
msg_fp = io.BytesIO(sig_block.encode('utf-8'))
ptxt_fp = io.BytesIO()
result = gpgme_ctx.verify(msg_fp, None, ptxt_fp)
# FIXME: this might require using the charset of the mime part.
plaintext = ptxt_fp.getvalue().decode('utf-8')
sig_fingerprints = []
for res_ in result:
sig_fingerprints += [res_.fpr]
return plaintext, sig_fingerprints
def verify_detached_signature (detached_sig, plaintext_bytes, gpgme_ctx):
detached_sig_fp = io.BytesIO(detached_sig.encode('ascii'))
plaintext_fp = io.BytesIO(plaintext_bytes)
ptxt_fp = io.BytesIO()
result = gpgme_ctx.verify(detached_sig_fp, plaintext_fp, None)
sig_fingerprints = []
for res_ in result:
sig_fingerprints += [res_.fpr]
return sig_fingerprints
def decrypt_block (msg_block, gpgme_ctx):
block_b = io.BytesIO(msg_block.encode('ascii'))
plain_b = io.BytesIO()
try:
sigs = gpgme_ctx.decrypt_verify(block_b, plain_b)
except:
return ("",[])
plaintext = plain_b.getvalue().decode('utf-8')
fingerprints = []
for sig in sigs:
fingerprints += [sig.fpr]
return (plaintext, fingerprints)
def choose_reply_encryption_key (gpgme_ctx, fingerprints):
reply_key = None
for fp in fingerprints:
try:
key = gpgme_ctx.get_key(fp)
if (key.can_encrypt == True):
reply_key = key
break
except:
continue
return reply_key
def email_to_from_subject (email_text):
email_struct = email.parser.Parser().parsestr(email_text)
email_to = email_struct['To']
email_from = email_struct['From']
email_subject = email_struct['Subject']
return email_to, email_from, email_subject
def import_lang(email_to):
if email_to != None:
for lang in langs:
if "edward-" + lang in email_to:
lang = "lang." + re.sub('-', '_', lang)
language = importlib.import_module(lang)
return language
return importlib.import_module("lang.en")
def generate_encrypted_mime (plaintext, email_from, email_subject, encrypt_to_key,
gpgme_ctx):
# quoted printable encoding lets most ascii characters look normal
# before the decrypted mime message is decoded.
char_set = email.charset.Charset("utf-8")
char_set.body_encoding = email.charset.QP
# MIMEText doesn't allow setting the text encoding
# so we use MIMENonMultipart.
plaintext_mime = MIMENonMultipart('text', 'plain')
plaintext_mime.set_payload(plaintext, charset=char_set)
if (encrypt_to_key != None):
encrypted_text = encrypt_sign_message(plaintext_mime.as_string(),
encrypt_to_key,
gpgme_ctx)
control_mime = MIMEApplication("Version: 1",
_subtype='pgp-encrypted',
_encoder=email.encoders.encode_7or8bit)
control_mime['Content-Description'] = 'PGP/MIME version identification'
control_mime.set_charset('us-ascii')
encoded_mime = MIMEApplication(encrypted_text,
_subtype='octet-stream; name="encrypted.asc"',
_encoder=email.encoders.encode_7or8bit)
encoded_mime['Content-Description'] = 'OpenPGP encrypted message'
encoded_mime['Content-Disposition'] = 'inline; filename="encrypted.asc"'
encoded_mime.set_charset('us-ascii')
message_mime = MIMEMultipart(_subtype="encrypted", protocol="application/pgp-encrypted")
message_mime.attach(control_mime)
message_mime.attach(encoded_mime)
message_mime['Content-Disposition'] = 'inline'
else:
message_mime = plaintext_mime
message_mime['To'] = email_from
message_mime['Subject'] = email_subject
reply = message_mime.as_string()
return reply
def email_quote_text (text):
quoted_message = re.sub(r'^', r'> ', text, flags=re.MULTILINE)
return quoted_message
def encrypt_sign_message (plaintext, encrypt_to_key, gpgme_ctx):
plaintext_bytes = io.BytesIO(plaintext.encode('ascii'))
encrypted_bytes = io.BytesIO()
gpgme_ctx.encrypt_sign([encrypt_to_key], gpgme.ENCRYPT_ALWAYS_TRUST,
plaintext_bytes, encrypted_bytes)
encrypted_txt = encrypted_bytes.getvalue().decode('ascii')
return encrypted_txt
def error (error_msg):
sys.stderr.write(progname + ": " + str(error_msg) + "\n")
def debug (debug_msg):
if edward_config.debug == True:
error(debug_msg)
def handle_args ():
if __name__ == "__main__":
global progname
progname = sys.argv[0]
if len(sys.argv) > 1:
print(progname + ": error, this program doesn't " \
"need any arguments.", file=sys.stderr)
exit(1)
main()