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REDDIT

Hybrid asymmetric encryption scheme

I
Nov 22, 2025 · 09:46

Hi, looking to get some eyeballs on the following scheme / idea


Imagine you have a ML-KEM keypair, and a Classic McEliece keypair.

You generate a shared secret with each KEM, then the result, you XOR it together to derive a final key

This final key will be used as the key to a symmetric algorithm.


Now, I understand, XORing sounds bad, and I should use some other hashing function / HKDF.


But logically speaking, I don't see any reason. I hope I can be convinced by your answers to ditch this XOR approach, but as far as I know, it appears to be secure.