# Quantum Cryptography Uses Fundamental Physics to Protect Secret Data

**In August, the NSA updated its list of encryption algorithms approved for government use, with specific references to the emerging threat of future quantum computers able to break the best encryption methods used today. Last week, quantum physicists confirmed the solid foundations of quantum cryptography, which offers total security guaranteed by the laws of physics.**

Quantum computers can process information in ways that have no equivalent in classical computing by exploiting subtle quantum phenomena. Quantum computers may theoretically be able to solve certain problems – including code breaking – much faster than classical computer and perform computations that would be otherwise impossible. This explains the enthusiasm of researchers, venture capitalists, and the intelligence community for the first quantum computing demonstrations.

“The Information Assurance Directorate (IAD) will initiate a transition to quantum resistant algorithms in the not too distant future,” notes the NSA. “Our ultimate goal is to provide cost effective security against a potential quantum computer.”

Last week *Hacked* reported that quantum physicists in the Netherlands, Spain, and the UK have confirmed in the lab that the weird instant correlations between remote “entangled” particles are real. The experimental result has important implications for both fundamental physics and the emerging science of quantum cryptography, which uses fundamental physics to keep data totally secure. The researchers noted:

This may enable the realization of large-scale quantum networks that are secured through the very same counter-intuitive concepts that inspired one of the most fundamental scientific debates for 80 years.

*Hacked* reached out to Gregoire Ribordy, Co-Founder and CEO of ID Quantique, a Swiss company focused on pioneering applications of quantum physics, to explore the current status, applications, and future prospects of quantum cryptography. Ribordy, who obtained his PhD for research on quantum cryptography from the University of Geneva in 2000, founded ID Quantique in 2001 with other three researchers of the University of Geneva, and has been running the company since then.

ID Quantique was the first company to bring a quantum random number generator to the market, and the first to deploy a Quantum Key Distribution (QKD) system in a real world application – vote counting in Geneva federal elections in 2007. The company has 3 business units: quantum safe security, random number generators, and scientific instrumentation.

## Quantum Security Based on Physics, Invulnerable to Computing Power

**Could you explain as simply as possible how quantum cryptography works?**

*Quantum cryptography uses one of the fundamentally distinctive features of quantum physics, the fact that observation causes a perturbation (aka Heisenberg Uncertainty Principle), to detect interception on a communication link.*

*To take a simple image, you can think of a standard communication link as a tennis game. The emitter writes the message he wants to send on a tennis ball and sends it to his partner, who catches the ball and reads the message. It is of course possible for an eavesdropper to intercept the ball, read the message and resend the ball.*

*In quantum communications, we replace the tennis ball with a soap bubble. If someone tries to intercept it, it bursts and the communication is perturbed.*

*In practice, we don’t use soap bubble, but single-photon pulses, which travel down optical fibers. Single-photons are quantum objects and as such they are perturbed by observation.*

**It is said that future, very powerful quantum computers will be able to break today’s best encryption schemes. Do you agree, and how can quantum cryptography help?**

*We have known since 1994 and the invention by Peter Shor of the so called Shor Algorithm that quantum computers can be used to break the most commonly used public key encryption schemes. This means that it is important to transition to so called quantum-safe encryption techniques, before quantum computers become widely available.*

*Quantum cryptography is one of the quantum-safe techniques that can be used to replace the vulnerable public key encryption schemes. Its security is based on physics, and not on mathematics, which means that computing power, whether classical or quantum, does not have any impact on its security.*

**What are the implications for quantum cryptography of the recent experimental confirmation that entangled correlations are real?**

*This impressive experimental work is the final brick that confirms that quantum physics, as a scientific theory, provides a complete view of the microscopic world. This is a confirmation, if needed, that quantum physics is a sound and solid theory. As quantum crypto is based on this theory, its security is further strengthened.*

**The NSA recently announced plans to make plans to transition to quantum-resistant algorithms. What are the implications for your business?**

*This announcement is a confirmation of the progress in the field of quantum computing and its implication to the security of cryptography. It is for us a very important validation point of what we have been saying for quite sometime now.*

*We now need to transition to quantum-safe cryptographic techniques and we need to do that early enough, i.e. before a quantum computer becomes available.*

*It is important to understand that one risk is that data has a long lifetime, it could be intercepted and stored in encrypted format today, until a quantum computer becomes available to decrypt it. This is a major risk for long lived data, for example in the government, financial or healthcare sectors.*

*If quantum crypto is used, this kind of vulnerability does not exist any more.*

**Who needs your quantum hardware to generate random numbers, and why?**

*In addition to quantum crypto, we have also developed quantum random number generators. The idea is to use the fundamentally random nature of quantum physics to generate high-quality random numbers.*

*An increasing number of security vulnerabilities are linked to poor random number generators, which lead to weak keys, passwords, etc. It is essential to use a high-entropy random number generator in every application where randomness is essential. These include security applications, but also lotteries and casinos, as well as scientific simulations.*

**As a pragmatic quantum businessman, what do you think of quantum weirdness, philosophical implications, many worlds, Bell telephones, FTL signaling via entanglement and all that?**

*I think that quantum physics is weird only because it goes against our intuition, but the more we will be exposed to it the less it will seem weird. It is likely that quantum physics will not be as weird for younger generations of quantum engineers as it is for us.*

*I’m also a strong believer in the potential of applications of quantum physics, most of which we probably can’t grasp yet.*

*Images from Id Quantique and Pixabay.*