Author Topic: ENCRYPTKEY  (Read 760 times)

Ablivadice

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ENCRYPTKEY
« on: June 02, 2017, 10:58:47 AM »
I was wondering if multiple RFM69 (at the moment I am up to 7 for my rube goldberg machine on different nodes) have the same node and network IDs but different encryptkey would they run into problems? I am going to a public event where others may have RFM69, I know the chances of running into people using the same network and node IDs is low but I am wondering if problems would occur?

Felix

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Re: ENCRYPTKEY
« Reply #1 on: June 02, 2017, 02:25:27 PM »
Look at the RFM69 libarry packet structure:



Important to understand that Nodes on the same frequency will share the same spectrum regardless of the settings.
In the packet structure above the network ID would always match since its outside the encrypted part.
You would then decrypt the message (which would be gibberish because the key does not match), but the destination node ID would be random (whatever decryption will decrypt that byte as).
So whenever that byte happens to match the listening node it would accept the (gibberish) message. Since it's garbage it won't really matter. But if you want to keep channels truly separated use different frequencies. Or at least different network IDs so the message would never decrypt if the network ID byte does not match.

Ablivadice

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Re: ENCRYPTKEY
« Reply #2 on: June 03, 2017, 03:27:12 PM »
Thanks for the reply.
So if I am reading this right, the RFM69 with a different encryption code (same network ID) would receive the code, but due to a different encryption would not be able to decrypt the message correctly. Then the node ID would be random with a small chance of being the same but this does not matter since the message received would be jumbled up anyways.

Felix

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Re: ENCRYPTKEY
« Reply #3 on: June 05, 2017, 05:26:45 PM »
It would decrypt the message then it would try to match the node ID, which has a chance of 1 in 255 to match the node ID.