As you are aware one of the big promises of Quantum Computers is the ability to break existing Encryption algorithms in a realistic time frame. If you are not aware of this, then here’s a quick primer on Computer Security/cryptography. Basically the current security of cryptography relies on certain “hard” problems—calculations which are practically impossible to solve without the correct cryptographic key. For example it is trivial to multiply two numbers together: 593 times 829 is 491,597 but it is hard to start with the number 491,597 and work out which two prime numbers must be multiplied to produce it and it becomes increasingly difficult as the numbers get larger. Such hard problems form the basis of algorithms like the RSA that would take the best computers available billions of years to solve and all current IT security aspects are built on top of this basic foundation.
Quantum Computers use “qubits” where a single qubit is able to encode more than two states (Technically, each qubit can store a superposition of multiple states) making it possible for it to perform massively parallel computations in parallel. This makes it theoretically possible for a Quantum computer with enough qubits to break traditional encryption in a reasonable time frame. In a theoretical projection it was postulated that a Quantum Computer could break a 2048-bit RSA encryption in ~8 hours. Which as you can imagine is a pretty big deal. But there is no need to panic as this is something that is still only theoretically possible as of now.
However this is something that is coming down the line so the worlds foremost Cryptographic experts have been working on Quantum safe encryption and for the past 3 years the National Institute of Standards and Technology (NIST) has been examining new approaches to encryption and data protection. Out of the initial 69 submissions received three years ago the group narrowed the field down to 15 finalists after two rounds of reviews. NIST has now begun the third round of public review of the algorithms to help decide the core of the first post-quantum cryptography standard.
They are expecting to end the round with one or two algorithms for encryption and key establishment, and one or two others for digital signatures. To make the process easier/more manageable they have divided the finalists into two groups or tracks, with the first track containing the top 7 algorithms that are most promising and have a high probability of being suitable for wide application after the round finishes. The second track has the remaining eight algorithms which need more time to mature or are tailored to a specific application.
The third-round finalist public-key encryption and key-establishment algorithms are Classic McEliece, CRYSTALS-KYBER, NTRU, and SABER. The third-round finalists for digital signatures are CRYSTALS-DILITHIUM, FALCON, and Rainbow. These finalists will be considered for standardization at the end of the third round. In addition, eight alternate candidate algorithms will also advance to the third round: BIKE, FrodoKEM, HQC, NTRU Prime, SIKE, GeMSS, Picnic, and SPHINCS+. These additional candidates are still being considered for standardization, although this is unlikely to occur at the end of the third round. NIST hopes that the announcement of these finalists and additional candidates will serve to focus the cryptographic community’s attention during the next round.
You should check out this talk by Daniel Apon of NIST detailing the selection criteria used to classify the finalists and the full paper with technical details is available here.
Source: Schneier on Security: More on NIST’s Post-Quantum Cryptography
– Suramya
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