Robust quantum data locking from phase modulation

Abstract

Quantum data locking is a unique quantum phenomenon that allows a relatively short key to (un)lock an arbitrarily long message encoded in a quantum state, in such a way that an eavesdropper who measures the state but does not know the key has essentially no information about the encrypted message. The application of quantum data locking in cryptography would allow one to overcome the limitations of the one-time pad encryption, which requires the key to have the same length as the message. However, it is known that the strength of quantum data locking is also its Achilles heel, as the leakage of a few bits of the key or the message may in principle allow the eavesdropper to unlock a disproportionate amount of information. In this paper we show that there exist quantum data locking schemes that can be made robust against information leakage by increasing the length of the shared key by a proportionate amount. This implies that a constant size key can still encrypt an arbitrarily long message as long as a fraction of it remains secret to the eavesdropper. Moreover, we greatly simplify the structure of the protocol by proving that phase modulation suffices to generate strong locking schemes, paving the way to optical experimental realizations. Also, we show that successful data locking protocols can be constructed using random codewords, which very well could be helpful in discovering random codes for data locking over noisy quantum channels.

A new result on the robustness of quantum data locking has been added

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Cited by in corpus (12)

• Advances in Quantum Cryptography
• Secure quantum key distribution with realistic devices
• A Quantum Enigma Machine: Experimentally Demonstrating Quantum Data Locking
• Quantum-locked key distribution at nearly the classical capacity rate
• Improving the performance of quantum cryptography by using the encryption of the error correction data
• Experimental quantum data locking
• Quantum cryptography beyond key distribution: theory and experiment
• Quantum data locking for high-rate private communication
• Continuous-variable quantum enigma machines for long-distance key distribution
• Photonic quantum data locking
• Quantum data hiding in the presence of noise
• Fault tolerant quantum data locking