Quantum computing and cryptography

Lock and key
(Source: Stockfresh)



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28 August 2015 | 0

Quantum computing, is like its physics counterpart, a bit of an odd field.

As uncertainty is a key part of quantum physics, it seems to have crept into the conceptual end of quantum computing too.

Put simply, a quantum computer is one that can calculate based on quantum states using superposition or entanglement to determine outcomes, instead of logic gates. Calculations can be based on massive parallel computing of all possible outcomes, potentially more or less simultaneously.

“Imagine a quantum computer that was able in seconds to decrypt the encryption algorithm for the likes of Secure Sockets Layer”

This massive potential computing power means that certain tasks which may have taken years of computation in the past, may be resolved in milliseconds. Practical quantum computers may make short work of calculating prime numbers, for example.

That would have a major knock-on effect for the likes of cryptography, and in particular the public key encryption system on which so much of our privacy online depends. Imagine a quantum computer that was able in seconds to decrypt the encryption algorithm for the likes of Secure Sockets Layer and the like, instead of the millions of years that were first predicted for brute force decryption when the system was designed.

Apocalypse soon
This is a real worry among some as recent breakthroughs from IBM, as well pressure from that defence fun house DARPA, have pushed quantum developments even further, bringing real quantum computers ever closer.

It has led some to conjecture what may happen if the various systems of public encryption systems were suddenly laid bare, or ‘cryptopocalypse’ as it has been termed.

Won’t someone please think of the…

But, backing up for a moment, cryptopgraphy based on prime numbers still works as long as takes longer to crack the prime factoring than it does to generate the cryptopgraphic keys based on them.

Therefore, unless the blackhats have exclusive use of the emerging quantum machines, surely the boffins developing them can set them to work determining ever larger primes. With the ability of the quantum machines to resolve such calculations, surely the emerging public key encryption would be a quantum leap stronger than before?

As has been proven mathematically by Euclid, but backed-up by work as recently as 2010, there are an infinite number of prime numbers. Therefore, there is a rather large number of them that are very large numbers. With computers able to easily calculate with certainty [pun intended] ever larger primes, surely even a quantum computer setting out to crack RSA style public key encryption would take a while. While no encryption is theoretically unbreakable, as yet, practical unbreakability is the goal.

As there are still Engima messages from World War II that have as yet defied decryption, because something can be broken, does not mean it will be broken.

So while the developments in quantum computing might be coming thick and fast, with another set of boffins now developing spherical crystals that might be viable as quantum optical routers/processors, practical unbreakability may yet be, well, practical if the new machines are set to either find new primes, or entirely new methods of encryption.


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