4 ms·
It can: you can just apply encryption after the FEC/ECC. This is done for example in GSM and I believe in many other radio systems. Of course there is one huge
by dfox 6y ago
It can: you can just apply encryption after the FEC/ECC. This is done for example in GSM and I believe in many other radio systems. Of course there is one huge caveat: it inherently means that you are doing MAC-then-Encrypt which is generally disliked as error-prone.
- fwip 6y agoRight, if you get a bitflip error in the encrypted data, decrypting it isn't going to yield something that the error-correcting-codes work on, right? It'll potentially ruin all your data, not just the single affected bit. I guess if GSM is doing it it must be useful, I need to read up on that.
- dfox 6y agoStream cipher preserves bit-flips between ciphertext and plaintext, which is useful property for this application. And many “military/diplomatic” ciphersystems used in second half of 20th century have various interesting properties wrt. error correction or non-propagation. My suspicion is that these properties are built by doing MAC-then-FEC-then-Encrypt and in some cases even by relying on limited error propagation of CBC mode. If you think about it, for these applications reliability is more interesting than strict authentication as the ciphertext of diplomatic “cable” or similar thing is sent through somewhat noisy channels and often was manually handled by fallible human radio operators while active MitM was not exactly feasible attack.
- fwip 6y agoThank you for all this explanation, I appreciate it. :)