Security of Quantum Key Distribution with One-Time-Pad-Protected Error Correction and Its Performance Benefits

Area of Science:

• Quantum Cryptography
• Information Security
• Theoretical Computer Science

Background:

• Quantum Key Distribution (QKD) protocols face information leakage during public classical channel communication, necessitating privacy amplification.
• A one-time pad (OTP) is a theoretically secure method for encrypting information, but its practical implementation in QKD requires careful analysis.
• Existing QKD security proofs often rely on asymptotic frameworks, which may not accurately reflect the performance with finite resources.

Purpose of the Study:

• To analyze the security and performance of an OTP-protected scheme within the non-asymptotic framework of quantum key distribution.
• To compare the achievable quantum key rate of the OTP-protected scheme with a reference QKD protocol using unprotected error correction.
• To evaluate the impact of the OTP scheme on computational requirements and privacy amplification efficiency.

Main Methods:

• Extended the security analysis of Tomamichel and Leverrier to an OTP-protected QKD scheme.
• Modeled QKD protocols as completely positive trace-preserving maps to define security via diamond distance.
• Analyzed the computational complexity for non-interactive low-density parity-check codes and privacy amplification compression.

Main Results:

• The OTP-protected QKD scheme achieves an identical quantum key rate to the reference protocol when the OTP key is sourced from the same QKD session's entropy pool.
• This equivalence in key rate is maintained for a fixed security level, defined by the diamond distance.
• The proposed OTP approach significantly reduces computational requirements, including a reduced encoding problem size and less compression for privacy amplification.

Conclusions:

• The OTP-protected QKD scheme offers a secure alternative that matches the key rate of unprotected error-correction methods.
• This technique simplifies QKD by avoiding the need for pre-shared keys between sessions and reducing computational overhead.
• The OTP scheme presents a promising avenue for enhancing the performance and practicality of quantum key distribution systems.