3 ms·
I've seen this argument quoted a couple of times and blindly accepted it as a traditional Fermi-style attack on the problem. This is the first time I've pondere
by ISL 13y ago
I've seen this argument quoted a couple of times and blindly accepted it as a traditional Fermi-style attack on the problem. This is the first time I've pondered the implementation.
Schneier's argument that 3.2K is a limit is perhaps not the best one? Dilution fridges let you into the millikelvin quickly. Optical cooling can readily reach nanokelvin. Power dissipation remains a significant problem, but the power requirement is reduced by ~10^9.
From the quantum-computing side of things, it's not that crazy to imagine a 256 bit quantum computer, especially if you have a GDP-caliber budget. Researchers worldwide are working hard on the relevant technological precursors.
- peterwaller 13y agoI'm under the impression that quantum computers buy you a square root. So instead of doubling the number of bits in your key to improve the strength of a key by a ludicrous amount, you should quadruple them. In addition to this, I don't know how well quantum computers help against (good) symmetric encryption. They help against certain types of PKI because they give you the aforementioned speedup in factoring large integers. However, I think Schneier's argument holds, because brute forcing 2^256 possible keys is.. well, see the argument above about forcing a counter through all those states. (apologies for not citing sources. Hopefully someone more knowledgeable can weigh in)
- archgoon 13y agoFor AES you are correct. The best known quantum attack is Grover's Search Algorithm (but emphasis on 'known' here), reducing the key space to 2^128. RSA, however, is based on prime factors, so it can be broken with Shor's Algorithm, which means it will take on the order of (256)^3 operations.