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f4exb / dsdcc

Digital Speech Decoder (DSD) rewritten as a C++ library
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NXDN and dPMR descrambler (Question) #35

Closed TheDefender44 closed 4 years ago

TheDefender44 commented 4 years ago

Hi - Just like the recently implemented MotoTRBO Basic Privacy feature, do you have any consideration in implementing a similar dPMR and NXDN 15-bit descrambler feature to DSDcc?

Both scrambling methods are very similar and well documented.

Thanks in advance for your input.

f4exb commented 4 years ago

Both scrambling methods are very similar and well documented.

dPMR is from ETSI and I have no doubt it should be well documented. However unlike what you mention in https://github.com/f4exb/sdrangel/issues/548 which this issue is a prerequisite NXDN is not ETSI. It is a proprietary protocol of ICOM and Kenwood. However intentionnally or not a paper has leaked that you can find on the Internet describing the protocol. NXDN implementation here is based on this paper.

I have had no time yet to check this but I am considering it although with not very high priority. You are very well welcome to contribute if you want to see things move a little faster.

I have to add that I have no means to test this so my implementation would be purely theoretical (like Motorola DMR BP by the way).

TheDefender44 commented 4 years ago

Thank you very much for your prompt response.

You are very well welcome to contribute if you want to see things move a little faster.

I would be more than happy to contribute to that effort in any way I can. Unfortunately, I do not have the knowledge to code C/C++. However, I have some dPMR hardware and can provide you with scrambled voice IQ samples with a defined scrambling key for you to run tests if needed. I can run the tests myself as well. I also have in my possession all the technical literature needed for the implementation.

If you are interested, please just let me know and I will be responsive.

f4exb commented 4 years ago

This would be indeed a very useful contribution.

Edit: following recent reports that DMR BP is not working (https://github.com/f4exb/sdrangel/issues/574) I will not attempt to make this change if I cannot validate them.

f4exb commented 4 years ago

There are already too many issues with DMR BP so I am not going to implement any kind of encryption in any mode any way