There’s nothing more dangerous, so the cryptoheads say, than quantum computing. Instead of using the state of a transistor to hold the value of a bit as in traditional computers, quantum computers use qubits, or quantum information like the polarization of a photon. According to people who know nothing about quantum computers, they are the beginning of the end, the breaking of all cryptography, and the Rise of the Machines. Lucky for us, [Jean-Philippe Aumasson] actually knows a thing or two about quantum computers and was able to teach us a few things at his Shmoocon talk this weekend, “Crypto and Quantum and Post Quantum”
This talk is the continuation of [Jean-Philippe]’s DEF CON 23 talk that covered the basics of quantum computing (PDF) In short, quantum computers are not fast – they’re just coprocessors for very, very specialized algorithms. Quantum computers do not say P=NP, and can not be used on NP-hard problems, anyway. The only thing quantum computers have going for them is the ability to completely destroy public key cryptography. Any form of cryptography that uses RSA, Diffie-Hellman, Elliptic curves is completely and totally broken. With quantum computers, we’re doomed. That’s okay, according to the DEF CON talk – true quantum computers may never be built.
The astute reader would question the fact that quantum computers may never be built. After all, D-Wave is selling quantum computers to Google, Lockheed, and NASA. These are not true quantum computers. Even if they’re 100 Million times faster than a PC, they’re only faster for one very specific algorithm. These computers cannot simulate a universal quantum computer. They cannot execute Shor’s algorithm, an algorithm that finds the prime factors of an integer. They are not scalable, they are not fault-tolerant, and they are not universal quantum computers.
https://hackaday.com/tag/d-wave/
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