5 ms·

Well, afaik key length isn't the problem. Weak algo is. I assume they use RSA, they should use ECC. 512 bits is more than enough. https://www.nsa.gov/business/

• tptacek 14y ago
  You can't use ECC for DKIM.
• mikeash 14y ago
  That doesn't make much sense. There are key lengths for which RSA is strong, and key lengths for which ECC is weak. ECC keys may be stronger at shorter lengths, but that hardly means that key length isn't the problem. After all, using a longer key would fix this problem.
  • dfox 14y ago
    Using ECC would solve this particular problem, because in both DKIM and DNSSEC usage of key lengths of 512 to 768 bits and not more are motivated by what can fit into one UDP DNS reply packet. Also for RSA signature size is equal to key length, and not some small multiple of security parameter and you don't want to expand messages by including large signature that might well be larger than actual payload.
    • mikeash 14y ago
      Right. Either expanding the key length or using ECC would fix it. So saying the problem isn't one of those, but is only the other, doesn't make much sense to me. ECC may even be a better solution, as you say, but that doesn't mean that the problem isn't also one of an insufficiently long key.