6 research outputs found
Function and secret sharing extensions for Blakley and Asmuth-Bloom secret sharing schemes
Ankara : The Department of Computer Engineering and the Institute of Engineering and Science of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 65-69.Threshold cryptography deals with situations where the authority to initiate or
perform cryptographic operations is distributed amongst a group of individuals.
Usually in these situations a secret sharing scheme is used to distribute shares
of a highly sensitive secret, such as the private key of a bank, to the involved
individuals so that only when a sufficient number of them can reconstruct the
secret but smaller coalitions cannot. The secret sharing problem was introduced
independently by Blakley and Shamir in 1979. They proposed two different solutions.
Both secret sharing schemes (SSS) are examples of linear secret sharing.
Many extensions and solutions based on these secret sharing schemes have appeared
in the literature, most of them using Shamir SSS. In this thesis, we apply
these ideas to Blakley secret sharing scheme.
Many of the standard operations of single-user cryptography have counterparts
in threshold cryptography. Function sharing deals with the problem of
distribution of the computation of a function (such as decryption or signature)
among several parties. The necessary values for the computation are distributed
to the participants using a secret sharing scheme. Several function sharing
schemes have been proposed in the literature with most of them using Shamir
secret sharing as the underlying SSS. In this work, we investigate how function
sharing can be achieved using linear secret sharing schemes in general and give
solutions of threshold RSA signature, threshold Paillier decryption and threshold
DSS signature operations. The threshold RSA scheme we propose is a generalization
of Shoup’s Shamir-based scheme. It is similarly robust and provably secure
under the static adversary model.
In threshold cryptography the authorization of groups of people are decided simply according to their size. There are also general access structures in which
any group can be designed as authorized. Multipartite access structures constitute
an example of general access structures in which members of a subset are
equivalent to each other and can be interchanged. Multipartite access structures
can be used to represent any access structure since all access structures are multipartite.
To investigate secret sharing schemes using these access structures,
we used Mignotte and Asmuth-Bloom secret sharing schemes which are based
on the Chinese remainder theorem (CRT). The question we tried to asnwer was
whether one can find a Mignotte or Asmuth-Bloom sequence for an arbitrary
access structure. For this purpose, we adapted an algorithm that appeared in the
literature to generate these sequences. We also proposed a new SSS which solves
the mentioned problem by generating more than one sequence.Bozkurt, İlker NadiM.S
cISP: A Speed-of-Light Internet Service Provider
Low latency is a requirement for a variety of interactive network
applications. The Internet, however, is not optimized for latency. We thus
explore the design of cost-effective wide-area networks that move data over
paths very close to great-circle paths, at speeds very close to the speed of
light in vacuum. Our cISP design augments the Internet's fiber with free-space
wireless connectivity. cISP addresses the fundamental challenge of
simultaneously providing low latency and scalable bandwidth, while accounting
for numerous practical factors ranging from transmission tower availability to
packet queuing. We show that instantiations of cISP across the contiguous
United States and Europe would achieve mean latencies within 5% of that
achievable using great-circle paths at the speed of light, over medium and long
distances. Further, we estimate that the economic value from such networks
would substantially exceed their expense
Why Is the Internet so Slow?!
In principle, a network can transfer data at nearly the speed of light. Today's Internet, however, is much slower: our measurements show that latencies are typically more than one, and often more than two orders of magnitude larger than the lower bound implied by the speed of light. Closing this gap would not only add value to today's Internet applications, but might also open the door to exciting new applications. Thus, we propose a grand challenge for the networking research community: building a speed-of-light Internet. To help inform research towards this goal, we investigate, through large-scale measurements, the causes of latency inflation in the Internet across the network stack. Our analysis reveals an under-explored problem: the Internet's infrastructural inefficiencies. We find that while protocol overheads, which have dominated the community's attention, are indeed important, reducing latency inflation at the lowest layers will be critical for building a speed-of-light Internet. In fact, eliminating this infrastructural latency inflation, without any other changes in the protocol stack, could speed up small object fetches by more than a factor of three
cISP: A Speed-of-Light Internet Service Provider
Low latency is a requirement for a variety of interactive network applications. The Internet, however, is not optimized for latency. We thus explore the design of wide-area networks that move data at nearly the speed of light in vacuum. Our cISP design augments the Internet's fiber with free-space microwave wireless connectivity over paths very close to great-circle paths. cISP addresses the fundamental challenge of simultaneously providing ultra-low latency while accounting for numerous practical factors ranging from transmission tower availability to packet queuing. We show that instantiations of cISP across the United States and Europe would achieve mean latencies within 5% of that achievable using great-circle paths at the speed of light, over medium and long distances. Further, using experiments conducted on a nearly-speed-of-light algorithmic trading network, together with an analysis of trading data at its end points, we show that microwave networks are reliably faster than fiber networks even in inclement weather. Finally, we estimate that the economic value of such networks would substantially exceed their expense
On Landing and Internal Web Pages
There is a rich body of literature on measuring and optimizing nearly every aspect of the web, including characterizing the structure and content of web pages, devising new techniques to load pages quickly, and evaluating such techniques. Virtually all of this prior work used a single page, namely the landing page (i.e., root document, "/"), of each web site as the representative of all pages on that site. In this paper, we characterize the differences between landing and internal (i.e., non-root) pages of 1000 web sites to demonstrate that the structure and content of internal pages differ substantially from those of landing pages, as well as from one another. We review more than a hundred studies published at top-tier networking conferences between 2015 and 2019, and highlight how, in light of these differences, the insights and claims of nearly two-thirds of the relevant studies would need to be revised for them to apply to internal pages.Going forward, we urge the networking community to include internal pages for measuring and optimizing the web. This recommendation, however, poses a non-trivial challenge: How do we select a set of representative internal web pages from a web site? To address the challenge, we have developed Hispar, a "top list" of 100,000 pages updated weekly comprising both the landing pages and internal pages of around 2000 web sites. We make Hispar and the tools to recreate or customize it publicly available