On the Security of Semi Device Independent QKD protocols

TL;DR

This paper analyzes the security of semi device-independent quantum key distribution protocols based on Random Access Codes, considering practical imperfections and minimal device assumptions to enhance security guarantees against sophisticated attacks.

Contribution

It introduces a security analysis for SDI-QKD protocols using RACs, accounting for detector imperfections and minimal device characterization to improve practical security.

Findings

Identifies critical success probability thresholds for security.

Establishes detection efficiency requirements for security.

Proposes minimal device assumptions to lower security barriers.

Abstract

While fully device-independent security in (BB84-like) prepare and measure Quantum Key Distribution (QKD) is impossible, it can be guaranteed against individual attacks in a semi device-independent (SDI) scenario, wherein no assumptions are made on the characteristics of the hardware used are made except for an upper bound on the the dimension of the communicated system. Studying security under such minimal assumptions is especially relevant in the context of the recent {\it quantum hacking} attacks wherein the eavesdroppers can not only construct the devices used by the communicating parties but are also able to remotely alter their behavior. In this work we study the security of a SDIQKD protocol based on the prepare and measure quantum implementation of a well-known cryptographic primitive, the Random Access Code (RAC). We consider imperfect detectors and establish the critical values of the security parameters (the observed success probability of the RAC and the detection efficiency) required for guaranteeing security against eavesdroppers with and without quantum memory. Furthermore we suggest a minimal characterization of the preparation device in order to lower the requirements for establishing a secure key.