Unconditionally secure key distribution without quantum channel

TL;DR

This paper introduces a novel, unconditionally secure key distribution method called probability key distribution that does not require quantum channels, potentially overcoming distance and technical limitations of quantum cryptography.

Contribution

The paper proposes a new key distribution scheme based on provable quantum one-way functions that enables secure communication without quantum channels, a significant departure from existing quantum methods.

Findings

Achieves unconditional security without quantum channels

Supports high secret key rates over any distance

Potential to enable global, mobile secure communication

Abstract

Key distribution plays a fundamental role in cryptography. Currently, the quantum scheme stands as the only known method for achieving unconditionally secure key distribution. This method has been demonstrated over distances of 508 and 1002 kilometers in the measurement-device-independent and twin-field configurations, respectively. However, quantum key distribution faces transmission distance issues and numerous side channel attacks since the basic physical picture requires the use of quantum channels between users. Even when quantum repeater and quantum constellation are used, commercializing quantum cryptography on a large scale remains unattainable due to the considerable expense and significant technical hurdles associated with establishing a global quantum network and facilitating mobile quantum communication. Here, by discovering the provable quantum one-way function, we propose another key distribution scheme with unconditional security, named probability key distribution, that promises users between any two distances to generate a fixed and high secret key rate. There are no quantum channels for exchanging quantum signals between two legitimate users. Non-local entangled states can be generated, identified and measured in the equivalent virtual protocol and can be used to extract secret keys. We anticipate that this discovery presents a paradigm shift in achieving unconditionally secure cryptography, thereby facilitating its widespread application on a global scale.