OP25 "New" Undocumented Config File Option - 'key'

[WdMnjvQXmYM3QYcxwihv]

In OP25, there is a file called multi_rx.py. On lines 114 - 115, there is a section of code:

        if config.has_key('key') and (config['key'] != ""):
            self.set_key(int(config['key'], 0))

This section of code appears to have been introduced on May 6, 2019.

It appears that it is looking in the config file for a 'key' setting; and if present will load the key value from the config file as an integer. (I'm not sure what happens if this value is a non-integer value.)

This, is as far as I can tell, not documented anywhere. It does not appear to be in the provided config file(s).

Other places it may show up:
frame_assembler_impl.cc - line 47-49

    void frame_assembler_impl::set_slotkey(int key) {
      d_sync.set_xor_mask(key);
    }

Which was also added at the same time.


Or here.

What is this config setting for?

 

[slicerwizard]

Looks like a 16 bit xor mask to decrypt traffic that is "protected" by a specific Motorola MotoTRBO Basic Privacy key.

 

[sniper1990]

If you check the real project,you can see what they want incorporate in the future.

WikiStart - OP25 - Open Source Mobile Communications

Redmine

osmocom.org

Greetings!

 

[WdMnjvQXmYM3QYcxwihv]

Thanks for that info.

I didn't see anything mentioned on the site about 'add "Motorola MotoTRBO Basic Privacy" decryption support' listed.

 

[sniper1990]

For now in a maybe future release.
Project Tasks
From here we have a number of tasks that immediately suggest themselves. In increasing order of difficulty these are:

• Understand P25, the physical layer and the messages being passed over the air.
• Implement a decoder which takes P25 signals and produces a message stream.
• Extend the !WireShark sniffer to allow sniffing of P25 message.
• Analyzing the various security issues and demonstrating the insecurity of P25 systems.
• Implement an IMBE decoder to recover voice traffic.
• Provide a practical logging service for P25 monitors.
• Incorporate the use of both the C4FM demodulator and the "CQPSK" demodulator.
• P25 Trunking support - capture, track, and log traffic on a P25 trunked radio system.
• [ReengineeringPage Re-engineering and re-factoring to support GNURadio 3.7 and later.]
• Support for newer P25 Phase 2/TDMA systems (a receiver is implemented, as of March 2015)
• Locate and track the locations of P25 mobile stations. No need to implement this as there are plenty of other solutions out there already that are quite good.
• Create a "live CD" so that people who don't want to install linux can simply boot from the CD then plug and play
• Expose OP25 receive and transmit functionality to GRC via new hier blocks and XML
• Scripted install to simplify setup for new users
• Support for Raspbian running Raspberry Pis
• Add DES-OFB decryption support
• Add AES-256 decryption support
• Add RC4 (a.k.a. Motorola ADP) decryption support
• Add P25 Phase 2 Tx support
• Add trunking transmit and receive to simulate a live P25 trunking system

As all Wiki pages, this page is editable so these ideas are not fixed in stone. Developers can simply click on the "Edit this page" link at the bottom of the page (although it is worth familiarizing oneself with Wiki formatting beforehand).
Greetings!