Side-channel-secure quantum key distribution with state-dependent correlated errors and Trojan-horse attack.

Area of Science:

• Quantum Information Science
• Cryptography
• Quantum Mechanics

Background:

• Quantum key distribution (QKD) offers theoretical security but faces practical vulnerabilities.
• Attacks on source and detector sides compromise QKD security.
• Existing protocols may require full quantum state descriptions.

Purpose of the Study:

• To enhance the security of the side-channel-secure (SCS) protocol against specific attacks.
• To maintain the SCS protocol's advantage of requiring only intensity bounds.
• To assess the impact of Trojan-horse attacks on SCS protocol security.

Main Methods:

• Encoding bits in vacuum and non-vacuum states within the SCS protocol.
• Introducing a third-party measurement node to deter attacks.
• Analyzing state-dependent correlated errors and Trojan-horse attacks.
• Performing numerical simulations to evaluate information leakage.

Main Results:

• The SCS protocol effectively repels detection-side and source-side attacks.
• Security is maintained without requiring full quantum state characterization.
• Trojan-horse attacks with reflected light intensity below 10^-6 yield minimal additional information for eavesdroppers.
• The SCS protocol demonstrates increased practicality.

Conclusions:

• The enhanced SCS protocol offers robust security against practical QKD threats.
• The protocol's reliance on intensity bounds simplifies implementation.
• This research significantly improves the feasibility of secure QKD systems.