diff --git a/.gitignore b/.gitignore index 5deb70a..68ecb9b 100644 --- a/.gitignore +++ b/.gitignore @@ -1,9 +1,4 @@ venv/ -__pycache__/ .idea/ -# misc testing scripts -testing*.py -# i have a symlink here so testing scripts can import gpgmymail -# as python expects `import gpgmymail` to be importing `gpgmymail.py` -gpgmymail.py +testing.py diff --git a/README.md b/README.md index fa11a05..a8dfe15 100644 --- a/README.md +++ b/README.md @@ -1,14 +1,7 @@ # gpgmymail -Takes an email from stdin and encrypts it to stdout using the recipient's PGP -key, provided as an argument when calling the script. - -Leaves a `X-gpgmymail-Status` header on the email, which has the following -statuses: - -* `entered` - the email has entered the encryption function, but not been - encrypted -* `encrypted` - the encryption function has encrypted the email +Takes an email from stdin and encrypts it using the recipient's PGP key, +provided as an argument when calling the script. Written to be a Sieve filter to be used with `sieve_extprograms`. Can be used in a Sieve filter e.g.: @@ -40,6 +33,5 @@ behaviour which is much better achieved with Sieve will be implemented, e.g. # Credits * Julian Klode for the [original code](https://github.com/julian-klode/ansible.jak-linux.org/blob/dovecot/roles/mailserver/files/usr/local/lib/dovecot-sieve-filters/gpgmymail) -* revsuine for modifications to gpgmymail, mostly to make it work well with - Thunderbird +* revsuine for modifications to gpgmymail diff --git a/gpgmymail b/gpgmymail index b42e891..7062dcf 100755 --- a/gpgmymail +++ b/gpgmymail @@ -24,12 +24,6 @@ works well for emails created with this tool. When encrypting, the tool preserves all headers in the original email in the encrypted part, and copies relevant headers to the output. When decrypting, any headers are ignored, and only the encrypted headers are restored. - -Emails exiting this script will have the 'X-gpgmymail-Status' header, which has -the following options: - -- entered: the email has entered the encrypt() function -- encrypted: the email has been encrypted """ import argparse @@ -46,6 +40,13 @@ import gnupg # constants DEFAULT_ENCODING='utf-8' # default is latin-1 which fails w some unicode chars +CTE_TO_ENCODER_DICT = { + "7bit": email.encoders.encode_7or8bit, + "8bit": email.encoders.encode_7or8bit, + "base64": email.encoders.encode_base64, + "quoted-printable": email.encoders.encode_quopri +} +DEFAULT_ENCODER = email.encoders.encode_7or8bit def is_message_encrypted(message: email.message.Message) -> bool: """Determines whether or not an email message is encrypted. @@ -55,34 +56,30 @@ def is_message_encrypted(message: email.message.Message) -> bool: return message.get_content_subtype() == "encrypted" -def set_email_header( - message: email.message.Message, - name: str, - value: str -) -> None: +def get_encoder_from_msg(msg: email.message.Message) -> typing.Callable: """ - Set the header of an email Message. Will either replace the first instance - of the header, or if the header is not present, will add the header. + Return a suitable encoder function from email.encoders based on an input + message. If the input message has no Content-Transfer-Encoding header, + or there is no encoder function corresponding to the CTE header, a default + encoder will be returned. - Note: Python passes objects as references, so there is no need for a return - value. - - :param message: the Message object to be modified - :param name: the email header to set - :param value: the value to set the header to + :param msg: an unencrypted email Message + :return: function from email.encoders, see + https://docs.python.org/3/library/email.encoders.html """ - if message.get(name): - message.replace_header(name, value) + cte = msg.get("Content-Transfer-Encoding") + if cte: + encoder = CTE_TO_ENCODER_DICT.get(cte) else: - message.add_header(name, value) + return DEFAULT_ENCODER + return encoder if encoder else DEFAULT_ENCODER def encrypt( message: email.message.Message, recipients: typing.List[str], *, unconditionally_encrypt: bool = False, - encoding: str = DEFAULT_ENCODING, - ignore_errors: bool = False, + encoding: str = DEFAULT_ENCODING ) -> str: """Encrypt given message @@ -92,19 +89,14 @@ def encrypt( False (default), will NOT encrypt if any of the following conditions are met: - The message is already encrypted - :param encoding: string for encoding to use for the gnupg.GPG object - :return: The encrypted email as a string""" - # mark the email as having passed through us - set_email_header(message, 'X-gpgmymail-Status', 'entered') + :return: The encrypted email as a string""" - # exclusion criteria: # some mail clients like Thunderbird don't like twice-encrypted emails, # so we return the message as-is if it's already encrypted - if not unconditionally_encrypt: - if is_message_encrypted(message): - return message.as_string() - + if is_message_encrypted(message) and not unconditionally_encrypt: + return message.as_string() + gpg = gnupg.GPG() gpg.encoding = encoding encrypted_content = gpg.encrypt(message.as_string(), recipients, armor=True) @@ -115,13 +107,13 @@ def encrypt( enc = email.mime.application.MIMEApplication( _data=str(encrypted_content).encode(), _subtype="octet-stream", - _encoder=email.encoders.encode_7or8bit + _encoder=get_encoder_from_msg(message) ) control = email.mime.application.MIMEApplication( _data=b'Version: 1\n', _subtype='pgp-encrypted; name="msg.asc"', - _encoder=email.encoders.encode_7or8bit + _encoder=get_encoder_from_msg(message) ) control['Content-Disposition'] = 'inline; filename="msg.asc"' @@ -140,9 +132,6 @@ def encrypt( if key.lower() not in headers_not_to_override: encmsg[key] = value - # we have encrypted the email, set our gpgmymail header appropriately - set_email_header(encmsg, 'X-gpgmymail-Status', 'encrypted') - return encmsg.as_string() def decrypt(message: email.message.Message, *, encoding: str = DEFAULT_ENCODING) -> str: @@ -164,8 +153,6 @@ def main() -> None: help="Encoding to use for the gnupg.GPG object") parser.add_argument('--unconditional', action="store_true", help="Encrypt mail unconditionally. By default, mail is not encrypted if it is already encrypted.") - parser.add_argument('--ignore-errors', action="store_true", - help="Ignore errors at certain error-prone points of the script.") parser.add_argument('recipient', nargs='*', help="Key ID or email of keys to encrypt for") args = parser.parse_args() @@ -178,8 +165,7 @@ def main() -> None: msg, args.recipient, unconditionally_encrypt=args.unconditional, - encoding=args.encoding, - ignore_errors=args.ignore_errors, + encoding=args.encoding )) if __name__ == '__main__':