Insecurity of Detector-Device-Independent Quantum Key Distribution

Area of Science:

• Quantum Information Science
• Cryptography
• Quantum Communication Security

Background:

• Quantum key distribution (QKD) aims to provide secure communication channels.
• Detector side channels are a known vulnerability in standard QKD systems.
• Detector-device-independent QKD (DDI-QKD) was proposed to mitigate these detector vulnerabilities.

Purpose of the Study:

• To rigorously assess the security claims of DDI-QKD against detector side-channel attacks.
• To investigate if DDI-QKD's security relies on postselected entanglement.
• To develop and demonstrate novel eavesdropping strategies targeting DDI-QKD.

Main Methods:

• Analysis of DDI-QKD security protocols.
• Development of specific eavesdropping strategies targeting receiver imperfections.
• Demonstration of attack validity even with self-built, non-malicious QKD apparatuses.

Main Results:

• The security of DDI-QKD does not rely on postselected entanglement as previously suggested.
• DDI-QKD is demonstrably insecure against detector side-channel attacks.
• Attacks exploiting receiver device imperfections were successfully demonstrated.

Conclusions:

• The purported robustness of DDI-QKD against detector side channels is invalidated.
• DDI-QKD systems are vulnerable to sophisticated eavesdropping attacks, even without malicious hardware.
• Further research is needed to develop truly secure device-independent QKD protocols.