Reply to recent scepticism about the foundations of quantum cryptography
This work defends the theoretical foundations of quantum cryptography against skepticism, but it is incremental as it refutes specific claims without introducing new methods.
The authors addressed claims by Hirota and Yuen that quantum cryptography has a fundamental flaw, arguing that the conclusion is unjustified due to a confusion between necessary and sufficient criteria for secrecy.
In a series of recent papers, Hirota and Yuen claim to have identified a fundamental flaw in the theory underlying quantum cryptography, which would invalidate existing security proofs. In this short note, we sketch their argument and show that their conclusion is unjustified --- it originates from a confusion between necessary and sufficient criteria for secrecy.