Table of Contents

This page is a collection of information relevant or useful during porting GPG Lacre to Python 3.x.

General remarks

There are no unit tests. We'll need them more than anything to be confident we aren't breaking anything while modernising the software.
Code isn't documented very well.
Installation is a manual process. This is error-prone and not very user-friendly, so we should consider providing tools to automate or semi-automate the process.
According to README, a workaround is necessary: gpg-mailgate is expected to be owned by nobody:nogroup. A dedicated user would be a better option.
Installation instructions (section about GPG Mailgate installation) recommend adding following lines to master.cf, but the manual suggests the first line should start with the word filter:

        gpg-mailgate    unix    -   n   n   -   -   pipe
            flags= user=nobody argv=/usr/local/bin/gpg-mailgate.py ${recipient}

`gpg-mailgate.py`

The core of this Postfix content filter, performing actual encryption of incoming messages.

It's a large, non-compiled Python script. Compiling it could improve overall performance, so we should at least consider it.
Most (if not all) functions defined here could be moved to a dedicated module and imported.
Custom log function could (and probably should) be replaced with the built-in logging module.

A Python module wrapping calls to /usr/bin/gpg binary.

Creates a new operating system process each time an operation needs to be performed.
Using an external package could be an option, e.g. gnupg.

A web interface to upload public keys and optionally a keyserver.

Each failed update of an existing key ends with all valid keys being deleted, which seems like an opportunity for an attacker to disable a person's mailbox encryption.
There might be a vulnerability in key-confirmation code: $email and $confirm are not sanitised before being passed to the database.
Key upload protocol is very simple:
1. An email address and a key is uploaded with HTTP POST.
2. Email asking for confirmation is sent to the email address given.
3. Confirmation is performed by sending a request with that email and a random string generated in the first step.