Remember, the NSA's current program, if successful, will handlenumbers up to four, not exactly the "large numbers" we were talking about earlier. No one has built a practical quantum computer that could break RSA, and that goal is still a long way off - decades, at the current rate of progress. Translating Shor's algorithm into practice is tremendously difficult. However, you needn't worry about your bank account. Making the number bigger shouldn't faze the quantum computer – it's enough to add a little more computing capacity. Quantum computers became big business in 1994, when Peter Shor demonstrated theoretically that a quantum computer could find the factors of a large number easily. In our example, you are given the number 337,499 and asked to find out which numbers (the "factors") should be multiplied together to produce 337,499. However, suppose someone just gives you a large number and asks you to work the process in reverse. In the jargon of computer science, the problem "scales polynomially". There's a simple process that you can follow and making the numbers a little bigger only makes the process take a little longer. Multiplying two large prime numbers is easy – say, 547 × 617 = 337,499. The Rivest-Shamir-Adleman (RSA) algorithm, which protects almost all e-commerce, relies on one fact that can be understood with primary-school maths (it can even be used to send love letters). Modern cryptography is, in many ways, a branch of applied mathematics. I was a little disappointed until I came up with a theory that when they went back to the NSA building, they would tear off the sweaters to reveal the long trenchcoats of a typical spy drama.īut iIt's no accident that our NSA funding managers looked like mathematicians. The NSA has been financially supporting non-classified quantum computing research at universities since the 1990s, and many academic journal articles acknowledge NSA support. It was already public knowledge that the NSA is interested in quantum computing.
The news here is that the NSA had its own secret experimental program. Just four!) This doesn't sound like much, but one has to start somewhere.Īnother portion supports research into quantum cryptography, which offers new, higher-security secret codes based on quantum mechanics. The NSA document, which can be found online, deals with the excitingly named project "Penetrating Hard Targets".Īn unknown portion of the US$80-million budget is devoted to building a small quantum processor, capable of counting up to four.
Why should the NSA care? Because the single most famous application of quantum computing is in code-breaking.ĭuring World War II, a team led by Alan Turing used a primitive computer to break the Nazis' Enigma code This research investigates ways to process information using the laws of quantum mechanics, rather than the familiar physics underlying present-day computer processors. One of these documents deals with the NSA's classified research program in the exotic field of quantum computing.