755 research outputs found
Preventing Denial of Service Attacks in IoT Networks through Verifiable Delay Functions
Permissionless distributed ledgers provide a promising approach to deal with
the Internet of Things (IoT) paradigm. Since IoT devices mostly generate data
transactions and micropayments, distributed ledgers that use fees to regulate
the network access are not an optimal choice. In this paper, we study a feeless
architecture developed by IOTA and designed specifically for the IoT. Due to
the lack of fees, malicious nodes can exploit this feature to generate an
unbounded number of transactions and perform a denial of service attacks. We
propose to mitigate these attacks through verifiable delay functions. These
functions, which are non-parallelizable, hard to compute, and easy to verify,
have been formulated only recently. In our work, we design a denial of service
prevention mechanism which addresses network heterogeneity, limited node
computational capabilities, and hardware-specific implementation optimizations.
Verifiable delay functions have mostly been studied from a theoretical point of
view, but little has been done in tangible applications. Hence, this paper can
be considered as a pioneer work in the field, since it builds a bridge between
this theoretical mathematical framework and a real-world problem
Efficient classical simulations of quantum Fourier transforms and normalizer circuits over Abelian groups
The quantum Fourier transform (QFT) is sometimes said to be the source of
various exponential quantum speed-ups. In this paper we introduce a class of
quantum circuits which cannot outperform classical computers even though the
QFT constitutes an essential component. More precisely, we consider normalizer
circuits. A normalizer circuit over a finite Abelian group is any quantum
circuit comprising the QFT over the group, gates which compute automorphisms
and gates which realize quadratic functions on the group. We prove that all
normalizer circuits have polynomial-time classical simulations. The proof uses
algorithms for linear diophantine equation solving and the monomial matrix
formalism introduced in our earlier work. We subsequently discuss several
aspects of normalizer circuits. First we show that our result generalizes the
Gottesman-Knill theorem. Furthermore we highlight connections to Shor's
factoring algorithm and to the Abelian hidden subgroup problem in general.
Finally we prove that quantum factoring cannot be realized as a normalizer
circuit owing to its modular exponentiation subroutine.Comment: 23 pages + appendice
Key Agreement for Large-Scale Dynamic Peer Group
Many applications in distributed computing systems,such as IP telephony, teleconferencing, collaborative workspaces,interactive chats and multi-user games, involve dynamic peergroups. In order to secure communications in dynamic peergroups, group key agreement protocols are needed. In this paper,we come up with a new group key agreement protocol, composedof a basic protocol and a dynamic protocol, for large-scaledynamic peer groups. Our protocols are natural extensions ofone round tripartite Diffie-Hellman key agreement protocol. Inview of it, our protocols are believed to be more efficient thanthose group key agreement protocols built on two-party Diffie-Hellman key agreement protocol. In addition, our protocols havethe properties of group key secrecy, forward and backwardsecrecy, and key independence
A Domain-Specific Language and Editor for Parallel Particle Methods
Domain-specific languages (DSLs) are of increasing importance in scientific
high-performance computing to reduce development costs, raise the level of
abstraction and, thus, ease scientific programming. However, designing and
implementing DSLs is not an easy task, as it requires knowledge of the
application domain and experience in language engineering and compilers.
Consequently, many DSLs follow a weak approach using macros or text generators,
which lack many of the features that make a DSL a comfortable for programmers.
Some of these features---e.g., syntax highlighting, type inference, error
reporting, and code completion---are easily provided by language workbenches,
which combine language engineering techniques and tools in a common ecosystem.
In this paper, we present the Parallel Particle-Mesh Environment (PPME), a DSL
and development environment for numerical simulations based on particle methods
and hybrid particle-mesh methods. PPME uses the meta programming system (MPS),
a projectional language workbench. PPME is the successor of the Parallel
Particle-Mesh Language (PPML), a Fortran-based DSL that used conventional
implementation strategies. We analyze and compare both languages and
demonstrate how the programmer's experience can be improved using static
analyses and projectional editing. Furthermore, we present an explicit domain
model for particle abstractions and the first formal type system for particle
methods.Comment: Submitted to ACM Transactions on Mathematical Software on Dec. 25,
201
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