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import key_loader
import pgpy
import email
from email.message import EmailMessage
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication
from email.mime.text import MIMEText
from copy import deepcopy
from random import choices as alphabet_random
from string import ascii_letters, digits
protected_headers = ['to', 'cc', 'from', 'reply-to', 'followup-to', 'subject', 'date',\
'message-id']
structural_headers = ['content-type']
overzealous_headers = ['mime-version', 'content-transfer-encoding']
def encrypt(msg: EmailMessage, recipients: list[str]) -> tuple[EmailMessage, bool]:
payload = wrap_body(deepcopy(msg))
rcpt_keys = load_keys(recipients)
if len(rcpt_keys) < 1:
return msg, False
enc_msg = pgpy.PGPMessage.new(payload.as_string())
for key in rcpt_keys:
enc_msg = key.encrypt(enc_msg)
container = MIMEMultipart(
'encrypted',
boundary=gen_boundary(),
protocol='application/pgp-encrypted'
)
container.preamble = 'This is an OpenPGP/MIME encrypted message (RFC 4880 and 3156)'
part1 = MIMEApplication(
_data='Version: 1\n',
_subtype='pgp-encrypted',
_encoder=email.encoders.encode_7or8bit
)
part1['Content-Description'] = 'PGP/MIME version identification'
part2 = MIMEApplication(
_data=str(enc_msg),
_subtype='octet-stream; name="encrypted.asc"',
_encoder=email.encoders.encode_7or8bit
)
part2['Content-Description'] = 'OpenPGP encrypted message'
part2['Content-Disposition'] = 'inline; filename="encrypted.asc"'
strip_extraneous_headers(part1)
strip_extraneous_headers(part2)
container.attach(part1)
container.attach(part2)
strip_extraneous_headers(container, ['mime-version'])
return container, True
def already_encrypted(msg: EmailMessage) -> bool:
if msg.get_content_type() in ['multipart/encrypted', 'application/pgp-encrypted']:
return True
for part in msg.iter_parts():
if already_encrypted(part):
return True
return False
def wrap_body(msg: EmailMessage) -> EmailMessage:
wrapped_msg = MIMEMultipart('mixed', boundary=gen_boundary(), protected_headers='v1')
strip_extraneous_headers(wrapped_msg, overzealous_headers + protected_headers)
copy_headers(msg, wrapped_msg, protected_headers)
if msg.is_multipart():
strip_extraneous_headers(wrapped_msg, structural_headers)
copy_headers(msg, wrapped_msg, structural_headers)
wrapped_msg.set_payload(msg.get_payload(decode=False))
else:
text_holder = MIMEText(msg.get_payload(decode=True), _charset='utf-8')
strip_extraneous_headers(text_holder, structural_headers)
copy_headers(msg, text_holder, structural_headers)
wrapped_msg.attach(text_holder)
return wrapped_msg
def copy_headers(orig_msg: EmailMessage, container: EmailMessage, headers: list) -> None:
for (header, value) in orig_msg.items():
if header.lower() in headers:
container.add_header(header, value)
def strip_extraneous_headers(msg: EmailMessage, strip_headers=overzealous_headers) -> None:
for header in msg.keys():
if header.lower() in strip_headers:
del msg[header]
def gen_boundary() -> str:
return '-' * 12 + ''.join(alphabet_random(ascii_letters + digits, k=24))
def load_keys(recipients: list[str]) -> list[pgpy.PGPKey]:
addrs = []
for recipient in recipients:
_display_name, addr = email.utils.parseaddr(recipient)
addrs.append(addr)
return key_loader.load_keys(addrs)
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