In 2014 i have released the first publicly available software that could monitor unencrypted voice calls on a TETRA network (and also some data: SDS, status etc). This software was called telive.
Previously the network operators intentionally did bother with encryption. This pushed network operators to use it. The world got more secure.
While better than nothing, this encryption was proprietary. The public could not audit it. Historically when the algorithm was not disclosed it was often found to be weak (such as A5/1 in GSM).
In 2023 Midnight Blue released their fantastic work on reverse engineering the TETRA encryption algorithms. They published an implementation of TEA1-4 and also found deliberate weakening of the TEA1 protocol.
So at the turn of 2025/2026 i have released an experimental version of my software which can monitor encrypted calls on a TETRA network. This is of course only if you know the encryption keys (see below on how to obtain them). Also i added support for the reduced keys for TEA1. And also released software to recover the reduced key from on-air traffic.
Hope this will further push operators to step up their security.
Continue reading “Listening to TETRA encrypted communications”
