Potentially Information-theoretic Secure Y00 Quantum Stream Cipher with Limited Key Lengths beyond One-Time Pad
This addresses the problem of secure encryption for quantum communication systems, offering a potential breakthrough beyond traditional limits, though it builds on prior work with incremental improvements.
The study demonstrates that the Y00 quantum stream cipher can achieve information-theoretic security against quantum-computational attacks when properly designed, potentially surpassing the Shannon limit of cryptography by using short secret keys expanded into pseudo-random running keys.
The previous work showed that the Y00 protocol could stay secure with the eavesdropper's guessing probability on the secret keys being strictly less than one under an unlimitedly long known-plaintext attack with quantum memory. However, an assumption that at least a fast correlation attack is completely disabled by irregular mapping. The present study shows that the Y00 protocol can be information-theoretic secure under any quantum-computational crypto-analyses if the Y00 system is well designed. The Y00 protocol directly encrypts messages with short secret keys expanded into pseudo-random running keys unlike One-Time Pad. However, it may offer information-theoretic security beyond the Shannon limit of cryptography.