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Perfect random numbers generated for 1st time: Why it matters
03 Jun 2026

Physicists at ETH Zurich have achieved a groundbreaking milestone by generating perfect random numbers using quantum physics.

The achievement is especially important for cryptography, passwords, and security keys.

Unlike software-generated "random" numbers that can be predicted due to fixed rules of classical electronics and computers, this new method ensures true unpredictability without any hidden rules or biases affecting the system.

Recent incidents highlight dangers of flawed random-number generation
Security risks

The need for true randomness is further highlighted by two recent incidents where flawed random-number generation nearly compromised global security.

In 2024, PuTTY, a popular SSH client, had a major vulnerability due to its random-number generator producing biased cryptographic signatures. The incident put secure server access across the tech industry at risk.

Similarly, in 2025, AMD Zen 5 RDSEED bug made headlines when a hardware random-number instruction produced predictable values but falsely reported success.

Breakthrough achieved using entanglement and randomness amplification
Quantum breakthrough

The ETH Zurich team used a phenomenon called entanglement in quantum mechanics to achieve their breakthrough. They didn't build a flawless machine but relied on randomness amplification.

"The resulting sequence of zeros and ones is now really perfectly random, and we can even certify that," says physicist Renato Renner of ETH Zurich.

They started with an imperfect random source and removed the bias using quantum mechanics techniques.

Bell test confirmed particles' behaviors were completely unpredictable
Innovative method

The team placed two superconducting quantum bits (qubits) separated by 30 meters and cooled to near absolute zero temperatures.

The qubits were entangled by having microwave photons travel between the chips.

This distance ensured that information couldn't travel fast enough, even at light speed, to interfere with the measurement.

A Bell test confirmed that the particles' behaviors were completely unpredictable and free of hidden rules.

Algorithm converted biased input into perfectly random output
Data transformation

An algorithm was used to process the results, converting 5.4GB of low-quality, biased input into over 45 million bits of perfectly random output.

This makes it impossible for an attacker to decode or guess the absolute unpredictability.

To demonstrate their method's superiority, the scientists encrypted an image of a sheep with their new perfect randomness technique.

Unlike ordinary randomness where faint traces could still be detected, this new method completely collapsed the image into pure static.