gpgmime.py

#!/usr/bin/env python3

"""Encrypt/Decrypt GPG/MIME messages"""

import os
import sys
import email.mime.application
import email.mime.multipart
import email.mime.message
import errno
import mimetypes
import gnupg

from argparse import ArgumentParser


def encrypt(message, recepients):
    encrypted_content = gnupg.GPG().encrypt(message.as_string(), recepients)

    enc = email.mime.application.MIMEApplication(
            _data=str(encrypted_content),
            _subtype='octet-stream; name="encrypted.asc"',
            _encoder=email.encoders.encode_7or8bit)
    enc['Content-Description'] = 'OpenPGP encrypted message'
    enc.set_charset('us-ascii')

    control = email.mime.application.MIMEApplication(
            _data='Version: 1\n',
            _subtype='pgp-encrypted',
            _encoder=email.encoders.encode_7or8bit)
    control.set_charset('us-ascii')

    encmsg = email.mime.multipart.MIMEMultipart(
            'encrypted',
            protocol='application/pgp-encrypted')
    encmsg.attach(control)
    encmsg.attach(enc)
    encmsg['Content-Disposition'] = 'inline'

    for key, value in message.items():
        if key not in ["Content-Disposition", "Content-Type"]:
            encmsg[key] = value

    return encmsg.as_string()

def decrypt(message):
    return str(gnupg.GPG().decrypt(message.as_string()))

def main():
    parser = ArgumentParser(description="""\
Unpack a MIME message into a directory of files.
""")
    parser.add_argument('-d', '--decrypt', action="store_true")
    parser.add_argument('recipient')
    args = parser.parse_args()

    msg = email.message_from_file(sys.stdin)

    if args.decrypt:
        sys.stdout.write(decrypt(msg))
    else:
        sys.stdout.write(encrypt(msg, [args.recipient]))
    
if __name__ == '__main__':
    main()