Posted in | Quantum Computing

The Downside of Quantum Computers

The era of totally fledged quantum computers lurks to destroy internet security that we are familiar with. Researchers are frantically trying to prepare new cryptographic methods before the influx of quantum computers, as cryptographers Tanja Lange (Eindhoven University of Technology) and Daniel J. Bernstein (University of Illinois at Chicago, USA) explain today in the Nature journal. In their publication they investigate the choices available for this post-quantum cryptography.

TU/e professor of Cryptology Tanja Lange. Photo: Bart van Overbeeke

The anticipation is that quantum computers will be manufactured a little beyond the year 2025. Such computers apply quantum-mechanical properties and can therefore crack some specific problems a lot faster than the present-day computers. This will be beneficial for calculating models for weather forecasts or creating new medicine. But, these processes also impact protection of data using ECC and RSA. With current technologies these systems will not be cracked in a hundred years but a quantum computer will crack these in a matter of days if not hours.

Sensitive data in the open

Without protection plenty of sensitive information will be exposed, even data from the past years. "An attacker can record our secure communication today and break it with a quantum computer years later. All of today's secrets will be lost," cautions Tanja Lange, professor of Cryptology at Eindhoven University of Technology. This includes private data, health and bank records, but also country secrets. Lange saw the significance of alternative systems way back in 2006 and is busy with promoting awareness and building new systems. "Fairly recently we're seeing an uptake of post-quantum cryptography in the security agencies, e.g., the NSA, and companies start demanding solutions."

Research consortium

Lange heads the research consortium PQCRYPTO comprising of eleven universities and companies. PQCRYPTO began in 2015 with 3.9 million euro funding from the European Commission to formulate new cryptographic methods.

This might seem like a lot of money, but is a factor of 100 less than what goes into building quantum computers. She cautions that it is vital to support research in cryptography. "Bringing cryptographic techniques to the end user takes often another 15 to 20 years, after development and standardization.


Shor's algorithm

In their Nature publication, Lange and Bernstein illustrate that a specific quantum algorithm, namely Shor's algorithm, cracks all cryptographic methods that are presently used to fix secure connections on the Internet. Candidates for post-quantum cryptography can approximately be classified into two types: they are either highly understood and confidence-inspiring but necessitate a lot of bandwidth or they are more convenient to use but offer more dubious security.


The publication can be found in an issue of Nature with special focus on topics related to quantum computers: from different candidates of basic building blocks of quantum computers till, for example the formation of new algorithms. The journal invited Lange to write about post-quantum cryptography.


Daniel J. Bernstein & Tanja Lange, Post-quantum cryptography, Nature (14 September 2017).  

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