1,683 research outputs found
A Quantum-Proof Non-Malleable Extractor, With Application to Privacy Amplification against Active Quantum Adversaries
In privacy amplification, two mutually trusted parties aim to amplify the
secrecy of an initial shared secret in order to establish a shared private
key by exchanging messages over an insecure communication channel. If the
channel is authenticated the task can be solved in a single round of
communication using a strong randomness extractor; choosing a quantum-proof
extractor allows one to establish security against quantum adversaries.
In the case that the channel is not authenticated, Dodis and Wichs (STOC'09)
showed that the problem can be solved in two rounds of communication using a
non-malleable extractor, a stronger pseudo-random construction than a strong
extractor.
We give the first construction of a non-malleable extractor that is secure
against quantum adversaries. The extractor is based on a construction by Li
(FOCS'12), and is able to extract from source of min-entropy rates larger than
. Combining this construction with a quantum-proof variant of the
reduction of Dodis and Wichs, shown by Cohen and Vidick (unpublished), we
obtain the first privacy amplification protocol secure against active quantum
adversaries
Quantum secure non-malleable-extractors
We construct several explicit quantum secure non-malleable-extractors. All
the quantum secure non-malleable-extractors we construct are based on the
constructions by Chattopadhyay, Goyal and Li [2015] and Cohen [2015].
1) We construct the first explicit quantum secure non-malleable-extractor for
(source) min-entropy ( is the length of the source and is the error
parameter). Previously Aggarwal, Chung, Lin, and Vidick [2019] have shown that
the inner-product based non-malleable-extractor proposed by Li [2012] is
quantum secure, however it required linear (in ) min-entropy and seed
length.
Using the connection between non-malleable-extractors and privacy
amplification (established first in the quantum setting by Cohen and Vidick
[2017]), we get a -round privacy amplification protocol that is secure
against active quantum adversaries with communication , exponentially improving upon the
linear communication required by the protocol due to [2019].
2) We construct an explicit quantum secure -source non-malleable-extractor
for min-entropy , with an output of size
and error .
3) We also study their natural extensions when the tampering of the inputs is
performed -times. We construct explicit quantum secure
-non-malleable-extractors for both seeded () as well as
-source case ()
RFID Key Establishment Against Active Adversaries
We present a method to strengthen a very low cost solution for key agreement
with a RFID device.
Starting from a work which exploits the inherent noise on the communication
link to establish a key by public discussion, we show how to protect this
agreement against active adversaries. For that purpose, we unravel integrity
-codes suggested by Cagalj et al.
No preliminary key distribution is required.Comment: This work was presented at the First IEEE Workshop on Information
Forensics and Security (WIFS'09) (update including minor remarks and
references to match the presented version
Composable Security in the Bounded-Quantum-Storage Model
We present a simplified framework for proving sequential composability in the
quantum setting. In particular, we give a new, simulation-based, definition for
security in the bounded-quantum-storage model, and show that this definition
allows for sequential composition of protocols. Damgard et al. (FOCS '05,
CRYPTO '07) showed how to securely implement bit commitment and oblivious
transfer in the bounded-quantum-storage model, where the adversary is only
allowed to store a limited number of qubits. However, their security
definitions did only apply to the standalone setting, and it was not clear if
their protocols could be composed. Indeed, we first give a simple attack that
shows that these protocols are not composable without a small refinement of the
model. Finally, we prove the security of their randomized oblivious transfer
protocol in our refined model. Secure implementations of oblivious transfer and
bit commitment then follow easily by a (classical) reduction to randomized
oblivious transfer.Comment: 21 page
Security of Plug-and-Play QKD Arrangements with Finite Resources
The security of a passive plug-and-play QKD arrangement in the case of finite
(resources) key lengths is analysed. It is assumed that the eavesdropper has
full access to the channel so an unknown and untrusted source is assumed. To
take into account the security of the BB84 protocol under collective attacks
within the framework of quantum adversaries, a full treatment provides the
well-known equations for the secure key rate. A numerical simulation keeping a
minimum number of initial parameters constant as the total error sought and the
number of pulses is carried out. The remaining parameters are optimized to
produce the maximum secure key rate. Two main strategies are addressed: with
and without two-decoy-states including the optimization of signal to decoy
relationship
Can Quantum Key Distribution Be Secure
The importance of quantum key distribution as a cryptographic method depends
upon its purported strong security guarantee. The following gives reasons on
why such strong security guarantee has not been validly established and why
good QKD security is difficult to obtain.Comment: This new version is a rewriting of the last v1 for a broader group of
readers. It also contains a new specific counter-example not in v
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