12,632 research outputs found
Getting the public involved in Quantum Error Correction
The Decodoku project seeks to let users get hands-on with cutting-edge
quantum research through a set of simple puzzle games. The design of these
games is explicitly based on the problem of decoding qudit variants of surface
codes. This problem is presented such that it can be tackled by players with no
prior knowledge of quantum information theory, or any other high-level physics
or mathematics. Methods devised by the players to solve the puzzles can then
directly be incorporated into decoding algorithms for quantum computation. In
this paper we give a brief overview of the novel decoding methods devised by
players, and provide short postmortem for Decodoku v1.0-v4.1.Comment: Extended version of article in the proceedings of the GSGS'17
conference (see https://gsgs.ch/gsgs17/
A tight security reduction in the quantum random oracle model for code-based signature schemes
Quantum secure signature schemes have a lot of attention recently, in
particular because of the NIST call to standardize quantum safe cryptography.
However, only few signature schemes can have concrete quantum security because
of technical difficulties associated with the Quantum Random Oracle Model
(QROM). In this paper, we show that code-based signature schemes based on the
full domain hash paradigm can behave very well in the QROM i.e. that we can
have tight security reductions. We also study quantum algorithms related to the
underlying code-based assumption. Finally, we apply our reduction to a concrete
example: the SURF signature scheme. We provide parameters for 128 bits of
quantum security in the QROM and show that the obtained parameters are
competitive compared to other similar quantum secure signature schemes
Belief propagation decoding of quantum channels by passing quantum messages
Belief propagation is a powerful tool in statistical physics, machine
learning, and modern coding theory. As a decoding method, it is ubiquitous in
classical error correction and has also been applied to stabilizer-based
quantum error correction. The algorithm works by passing messages between nodes
of the factor graph associated with the code and enables efficient decoding, in
some cases even up to the Shannon capacity of the channel. Here we construct a
belief propagation algorithm which passes quantum messages on the factor graph
and is capable of decoding the classical-quantum channel with pure state
outputs. This gives explicit decoding circuits whose number of gates is
quadratic in the blocklength of the code. We also show that this decoder can be
modified to work with polar codes for the pure state channel and as part of a
polar decoder for transmitting quantum information over the amplitude damping
channel. These represent the first explicit capacity-achieving decoders for
non-Pauli channels.Comment: v3: final version for publication; v2: improved discussion of the
algorithm; 7 pages & 2 figures. v1: 6 pages, 1 figur
LEDAkem: a post-quantum key encapsulation mechanism based on QC-LDPC codes
This work presents a new code-based key encapsulation mechanism (KEM) called
LEDAkem. It is built on the Niederreiter cryptosystem and relies on
quasi-cyclic low-density parity-check codes as secret codes, providing high
decoding speeds and compact keypairs. LEDAkem uses ephemeral keys to foil known
statistical attacks, and takes advantage of a new decoding algorithm that
provides faster decoding than the classical bit-flipping decoder commonly
adopted in this kind of systems. The main attacks against LEDAkem are
investigated, taking into account quantum speedups. Some instances of LEDAkem
are designed to achieve different security levels against classical and quantum
computers. Some performance figures obtained through an efficient C99
implementation of LEDAkem are provided.Comment: 21 pages, 3 table
Ternary Syndrome Decoding with Large Weight
The Syndrome Decoding problem is at the core of many code-based
cryptosystems. In this paper, we study ternary Syndrome Decoding in large
weight. This problem has been introduced in the Wave signature scheme but has
never been thoroughly studied. We perform an algorithmic study of this problem
which results in an update of the Wave parameters. On a more fundamental level,
we show that ternary Syndrome Decoding with large weight is a really harder
problem than the binary Syndrome Decoding problem, which could have several
applications for the design of code-based cryptosystems
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