As the amount of data stored in devices and shared over the internet continuously increases, computer scientists worldwide are trying to devise new approaches to secure communications and protect sensitive information. Some of the most well-established and valuable approaches are cryptographic techniques, which essentially encrypt (i.e., transform) data and texts exchanged between two or more parties, so that only senders and receivers can view it in its original form.Physical unclonable functions (PUFs), devices that exploit "random imperfections" unavoidably introduced during the manufacturing of devices to give physical entities unique "fingerprints" (i.e., trust anchors). In recent years, these devices have proved to be particularly valuable for creating cryptographic keys, which are instantly erased as soon as they are used.

Researchers at Peking University and Jihua Laboratory have recently introduced a new system to generate cryptographic primitives, consisting of two identical PUFs based on aligned carbon nanotube (CNT) arrays. This system, introduced in a paper published in Nature Electronics, could help to secure communications more reliably, overcoming some of the vulnerabilities of previously proposed PUF devices.

"Classical cryptography uses cryptographic algorithms and keys to encrypt or decrypt information, and the most popular strategies are Rivest, Shamir, and Adleman (RSA) encryption," Zhiyong Zhang, one of the researchers who carried out the study, told TechXplore. "In an asymmetric algorithm, the public key can be accessed by anyone, but the public key cracking requires factoring a very large number, which is extremely difficult for a classical computer. This task has, however, been shown mathematically to be accomplishable in polynomial time using a quantum computer."

One of the most employed cryptographic strategies today is symmetric encryption, which shares the same "secret keys" for encryption and decryption with all users participating in a specific conversation. These strategies generally store secret keys in a non-volatile memory, which is vulnerable to physical and side-channel cyber-attacks.

In recent years, researchers have thus been exploring alternative cryptographic approaches, including quantum key distribution (QKD). QKD methods exploit concepts rooted in quantum theory to protect communications. Specifically, they leverage the intrinsic disturbances affecting quantum systems while they are being measured.