I’ve Finally Discovered the Secret to Generating True Random Numbers

It rhymes with Eeny, meeny, minnie, moo, catch a tiger by its toes. Yet even children realize counting rhymes like this are ineffective for making genuinely random choices. Remember when you first discovered you could influence the outcome by selecting your starting point carefully?

You might think flipping a coin or rolling a die is better, but proving these outcomes are random is a challenge. These methods are not genuinely random; knowing the precise conditions like positioning, trajectory, gravity, or friction lets you predict the results. True randomness is indeed elusive.

The exciting part is that randomness is an inherent aspect of the universe, evident in quantum mechanics. Quantum particles like electrons and photons choose paths based on pure randomness, with no discernible cause behind quantum events. The University of Colorado Randomness Beacon, affectionately known as Kirby, exploits this phenomenon. This year, it launched as the first publicly available source of traceable, verifiable true random numbers.

You might question who requires such high levels of randomness. After all, dice and coins have entertained us for millennia. However, some scenarios demand maximum randomness. “People don’t realize it, but without randomness, digital life lacks safety and fairness,” says Nemitali Azienka, a computer scientist from Nottingham Trent University in the UK. He explains that whenever you access a secure webpage or create a strong password, randomness plays a role. Even machine learning incorporates randomness in its training.

Randomness also supports democratic processes. For instance, in Chile, politicians face random audits, but those targeted often feel victimized. “Everyone claims it’s a witch hunt,” says Christer Shalm, one of the CURBy creators at the National Institute of Standards and Technology (NIST). When random beacons are used to derive numbers from genuinely random sources, such claims become much harder to substantiate.

Currently, the Chilean government relies on various factors, like seismic activity and a local radio station’s output, for randomness, but these aren’t entirely random either—after all, seismic events occur for specific reasons and the radio playlist is curated. Moreover, such methods lack full traceability as seismic data isn’t regularly accessible. This is where CURBy shines.

Quantum Randomness Generator

A decade ago, Schalm noted that the system was “held together by duct tape and hopes.” At that time, researchers had just begun to verify CURBy’s principles. Since then, they’ve worked to enhance the system’s speed, automation, and accessibility for all internet users.

Today, CURBy boasts a cutting-edge facility that handles thousands of requests daily. It may bolster democracy, enhance trust in justice systems, and even bring tranquility to family game nights. “CURBy embodies a practical, accessible quantum technology. This development excites me,” says Peter Brown, a physicist at the Polytechnic University of Paris.

Generating genuinely random numbers is tricky. Apart from quantum methods, most number-generation mechanisms rely on some underlying processes, making true randomness rare in the universe. Computer games often utilize “pseudo-random numbers” to form secure passwords from a seeded number; knowing this seed and algorithm eliminates randomness in your passwords.

One could delve deeper and use “high entropy” randomness sources, like the unpredictable timing of radioactive decay in materials like cobalt-60 or strontium-90. While this constitutes a random quantum event, it’s difficult to make user-friendly, and proving the legitimacy of generated numbers is a challenge without an observer present.

While this creates a high-stakes game of Yahtzee, CURBy allows you to do away with the dangers associated with radiation. Instead, CURBy utilizes pairs of photons interconnected by a quantum phenomenon called quantum entanglement.

When two entities are entangled, they behave as if they were a single entity. This compelling occurrence happens when you measure one, and then similarly measure the other. The first measurement can influence the second, even if the quantum objects are far apart. It’s akin to rolling two dice such that one consistently results in six when the other is one.

This entanglement, which Albert Einstein famously referred to as “spooky action at a distance,” defies typical understanding. Neither object transmits any signals, yet they remain connected in this way. The exact mechanism remains a mystery.

At CURBy, entanglement appears in the measurement of a property called polarization. Entangled photon pairs are separated and sent through optical fibers to two different locations, 100 meters apart. Measurements of polarization occur in quick succession at both sites.

The results of these measurements are compared, revealing subtle correlations. Under “classical” conditions, this correlation has limitations; however, if it’s genuinely quantum and random, it allows for generating numbers outside those constraints. CURBy purifies this inherent randomness using a method called Trevisan extraction. It can handle around 250,000 polarization measurements per second, requiring approximately 15 million measurements for a single output—a string of 512 utterly random binary digits (bits) ready for use.

If you’re curious about the randomness of these bits, there’s an algorithm for that. For a string with 512 bits, each either a 0 or a 1, there are 2⁵¹² potential combinations. “The possibilities are immense,” Shalm remarks.

While all combinations are equally probable, Shalm and his team assessed the probability of specific bit strings appearing. Uniformity isn’t complete, yet it can be quite high. Consider aiming for an even road. If the incline is 1 in 10, it becomes a steep rise. Even a 1 in 100 slope or a 1 meter bump in a 100-meter stretch is noticeable. The randomness slope of CURBy is 1 in 184 quintillion, which is as random as one might need.

Proof of Randomness

CURBy’s standout feature isn’t just its randomness. The ability to trace the source and verify the randomness of the numbers is crucial. “Currently, there’s no reliable method for any random number generator,” Schalm asserts.

To ensure traceability, CURBy employs blockchain mathematics, known for securing digital assets like NFTs and cryptocurrencies. This method facilitates transparency about actions taken, timings, and the responsible parties in scenarios devoid of trust, linking everything back to the experiment’s original results.

However, the system’s accessibility is limited since the entire process involves multiple organizations. NIST forwards quantum data to facilities at the University of Colorado Boulder, which processes it, while an independent cryptographic service, the Distributed Randomness Beacon Daemon, adds its factors to extract genuine randomness from the measurements, generating the final uniform binary string.

“It’s like a chronological web,” observes Schalm. “No single entity has complete control over the random bits, allowing scrutiny for foul play or alterations.”

According to Brown, the integration of comprehensive physics with high-level security analysis is “quite remarkable.” He notes that quantum technologies are still emerging, with few complete products available. Yet will CURBy prove valuable? Absolutely, he argues, but there are situations where traceable randomness should be avoided. “You wouldn’t want to base your passwords on publicly accessible random sources,” he expounds.

Nonetheless, in contexts like jury selections, judge appointments, lottery outcomes, and random sampling in clinical trials, traceable randomness holds significant potential. Mathematician Artur Ekert from Oxford University expresses admiration too. The CURBy team’s melding of quantum and classical physics to produce innovative, accessible technology signals an exciting future.

Furthermore, CURBy is designed to adapt to future technologies, ensuring that genuine randomness embeds itself in our lives, promoting fairness and safety. It certainly surpasses a coin toss.