Precise evaluation of leaked information with universal2 privacy amplification in the presence of quantum attacker
This work addresses security in quantum cryptography for scenarios involving quantum attackers, representing a theoretical advancement rather than an incremental improvement.
The paper tackles secret key extraction against a quantum eavesdropper by proposing new quantum privacy amplification theorems based on quantum conditional Rényi entropy, deriving an exponential decreasing rate for leaked information and the asymptotic equivocation rate, which were previously unattained in quantum settings.
We treat secret key extraction when the eavesdropper has correlated quantum states. We propose quantum privacy amplification theorems different from Renner's, which are based on quantum conditional Rényi entropy of order 1+s. Using those theorems, we derive an exponential decreasing rate for leaked information and the asymptotic equivocation rate, which have not been derived hitherto in the quantum setting.