4,651 research outputs found
Experimental implementation of bit commitment in the noisy-storage model
Fundamental primitives such as bit commitment and oblivious transfer serve as
building blocks for many other two-party protocols. Hence, the secure
implementation of such primitives are important in modern cryptography. In this
work, we present a bit commitment protocol which is secure as long as the
attacker's quantum memory device is imperfect. The latter assumption is known
as the noisy-storage model. We experimentally executed this protocol by
performing measurements on polarization-entangled photon pairs. Our work
includes a full security analysis, accounting for all experimental error rates
and finite size effects. This demonstrates the feasibility of two-party
protocols in this model using real-world quantum devices. Finally, we provide a
general analysis of our bit commitment protocol for a range of experimental
parameters.Comment: 21 pages (7 main text +14 appendix), 6+3 figures. New version changed
author's name from Huei Ying Nelly Ng to Nelly Huei Ying Ng, for consistency
with other publication
Robust quantum data locking from phase modulation
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.Comment: A new result on the robustness of quantum data locking has been adde
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