megolm_filter.py

This script can be used to modify your offline megolm key backups from a shell. The main use of this is to filter what keys you'd like to share with another user (let's say you have a 1:1 chat, and the other user lost all their keys and you need to give them access without giving access to all of your rooms). There is currently no Element-based support for this, so this script can help in the meantime.

I've tested the output and input format with my own room keys and it has worked so far.

usage: megolm_filter.py [-h] [-o OUTPUT] [--plain] [file] [room_id]

Operate on megolm session backups.

positional arguments:
  file                 megolm session data
  room_id              Room id to filter (optional)

options:
  -h, --help           show this help message and exit
  -o, --output OUTPUT  Output to file
  -p, --plain          Returns the plain unencrypted content

You can do this fairly easily with:

 $ ./megolm_filter.py element-keys.txt '!room1:matrix.org' '!room2:matrix.org' ...

You need to have PyCryptodome installed in order for this script to work.

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Copyright (C) 2019 Aleksa Sarai cyphar@cyphar.com
Copyright (C) 2025 Lain Iwakura lain@serialexperiments.club

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.