Transient Attack against the KLJN Secure Key Exchanger

TL;DR

This paper reveals a transient vulnerability in the ideal KLJN secure key exchange system, demonstrating an attack during initial connection transients and proposing a defense protocol that effectively reduces information leakage.

Contribution

The paper identifies a transient attack vector on the KLJN system and introduces a novel defense protocol to mitigate this specific security vulnerability.

Findings

Transient attack can extract information during initial connection phase.

The proposed defense protocol significantly reduces information leakage.

Simulations confirm the effectiveness of the defense method.

Abstract

We demonstrate the security vulnerability of the ideal Kirchhoff-Law-Johnson-Noise (KLJN) key exchanger against transient attacks. Transients start when Alice and Bob connect the wire to their chosen resistor at the beginning of each clock cycle. A transient attack takes place during a short duration of time, before the transients reflected from the end of Alice and Bob mix together. The information leak arises from the fact that Eve (the eavesdropper) monitors the cable, and analyzes the transients during this time period. We will demonstrate such a transient attack, and, then we introduce a defense protocol to protect against the attack. Computer simulations demonstrate that after applying the defense method the information leak becomes negligible.