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iMessage uses short RSA 1280-bit keys which could be cracked by a well funded attacker. [1]https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://w

• snuxoll 9y ago
  1280-bit keys are still mostly sufficient for now, this isn’t a website where every party is relying on the key of the server being heavily resistant to protects millions of users - every device has a unique key. Still, you are correct that a determined adversary, potentially one capable of purchasing a quantum computer with enough quibits could factor the device key. It would be nice to see Apple move to a large enough ECC key which would improve security against quantum computing attacks in particular.
  • fossuser 9y ago
    I don’t think there any quantum computers yet? The last I heard there was one example of factoring 15 and I think it assumed the factors? Did something change?
    • snuxoll 9y ago
      True ones are still off in the near future, ones with enough quibits for Shor’s algorithm are far enough away for now as well - which is why I generally feel safe with the current level of cryptography Apple uses with iMessage. I won’t underestimate the rate at which they are developed though, it takes 2x the key size as the number of quibits to run Shor’s algorithm - ~2600 is a lot smaller than 4096, and even then who knows how much time we have until that happens.