Quantum Cryptography II: How to re-use a one-time pad safely even if P=NP

When elementary quantum systems, such as polarized photons, are used to transmit digital information, the uncertainty principle gives rise to novel cryptographic phenomena unachievable with traditional transmission media, e.g. a communications channel on which it is impossible in principle to eavesdrop without a high probability of being detected. With such a channel, a one-time pad can safely be reused many times as long as no eavesdrop is detected, and, planning ahead, part of the capacity of these uncompromised transmissions can be used to send fresh random bits with which to replace the one-time pad when an eavesdrop finally is detected. Unlike other schemes for stretching a one-time pad, this scheme does not depend on complexity-theoretic assumptions such as the difficulty of factoring.     

How to safely close a discussion

In the secure communication problem, we focus on safe termination. In applications such as electronic transactions, we want each party to be ensured that both sides agree on the same state: success or failure. This problem is equivalent to the well-known coordinated attack problem. Solutions exist. They, however, concentrate on the probability of disagreement, and attack incentives have been overlooked so far. Furthermore, they focus on a notion of round and are not optimal in terms of communication complexity.To solve the safe termination problem, we revisit the Keep-in-Touch protocol that we introduced in 2003. Considering the communication complexity, the probability of unsafe termination, and the attack incentive, we prove that the Keep-in-Touch protocol is optimal.     

“NP = P?” and restricted partitions

This paper establishes a relationship between partition theory and the tractability of NP-complete problems. We define a special kind of partitions called restricted partitions and give a sufficient condition, in terms of some supposed property of restricted partitions, for “NP = P.” In validating the conclusion we propose a dynamic-programming algorithm with a set of natural numbers as its parameter, whose time complexity depends on the restricted partition property of this set.     

How to sample from a truncated distribution if you must

Sampling from a truncated distribution is difficult. There are currently two major methods proposed for solving this task. The first proposed solution is a random-walk MCMC algorithm. Although it eventually gives the correct distribution, it can be very slow in multi-modal distributions. The second approach called the ellipsoid method is practically more efficient for problems in which users have good prior information, but a correctness is not guaranteed. In this paper, we present a framework which can unify these two approaches. The key idea is to merge both methods into a single Markov chain using a trick called Metropolis-coupled MCMC. Once merged, they can validly exchange information to each other. Although the chain constructed from the ellipsoid approach cannot be proven to be correct, it usually rapidly converges to a useful stationary distribution, and its information can help the other chain constructed by the random-walk approach to converge faster to the correct distribution.     

How to Select and Evaluate a DBMS

A DBMS package is the single most costly piece of software an organization ever purchases or develops. Because of the increased cost of personnel, however, the probability of reaching the decision to develop this software is remote. As a result, the correct selection must be made the first time, and a practical methodology is needed to guide this process.     

How to program and configure a heterogeneous multiprocessor

This paper describes a software environment that allows the programming and configuration of a heterogeneous multiprocessor architecture consisting of specialized hardware and a general purpose trasputer net. Run-time-behavior estimation is done at a compile time by using directed dataflow graphs to represent the program and a database containing all the relevant information about functions. The system offers the implementations of functions running on different hardware platforms, static configuration and scheduling, and integrated performance measurement. We show how programmers can handle such a system without any deeper knowledge of the underlying specialized hardware.     

How to make and defend a proposal in a deliberation dialogue

In this paper it is shown how tools developed in argumentation theory and artificial intelligence can be applied to the development of a new dialectical analysis of the speech act of making a proposal in a deliberation dialogue. These tools are developed, modified and used to formulate dialogue pre-conditions, defining conditions and post-conditions for the speech act of making a proposal in a deliberation dialogue. The defining conditions set out what is required for a move in a dialogue to count as the making of a proposal by one of the parties. What is required are the conditions that (1) the move fit the requirements of the argumentation scheme for practical reasoning, and (2) the premises are propositions describing common goals of both parties or propositions that they reasonably consider means to achieve these goals. The analysis goes beyond the standard speech act approach by specifying not only the normative requirements for making a well-formed proposal, but also the requirements for responding to it by questioning or criticizing it, and the requirements for defending it.     

如何构建简易、高效、实用的网络运行监控系统

由MRTG PingPlotter 3Cdaemon组合建立的三位一体、立体交叉的网络运行监控系统简易、高效、实用,从流量监控、路由跟踪、安全管理三个方面全方位呵护我们的网络。     

怎样进行PC机与单片机的串行通信系统的设计

本文总结了异步串行接口在PC机与单片机串行通信中的应用，并结合实例比较务实地从硬件和软件两个方面对PC机与单片机串行通信系统的设计进行了比较完整的论述。     

How to Build a Robot that is Conscious and Feels

Following arguments put forward in my book (Why red doesn??t sound like a bell: understanding the feel of consciousness. Oxford University Press, New York, USA, 2011), this article takes a pragmatic, scientist??s point of view about the concepts of consciousness and ??feel??, pinning down what people generally mean when they talk about these concepts, and then investigating to what extent these capacities could be implemented in non-biological machines. Although the question of ??feel??, or ??phenomenal consciousness?? as it is called by some philosophers, is generally considered to be the ??hard?? problem of consciousness, the article shows that by taking a ??sensorimotor?? approach, the difficulties can be overcome. What remains to account for are the notions of so-called ??access consciousness?? and the self. I claim that though they are undoubtedly very difficult, these are not logically impossible to implement in robots.     

P2P应用中一种多层NAT穿透解决方案的设计与实现

在说明多层NAT各种穿越模型结构的基础上,剖析了多层NAT打孔穿越中存在的问题,提出了根据网络环境适当选取节点作为超级节点,为需要通信的两个节点指定超级节点辅助它们通信的设计思想。然后介绍了具体方案：包括超级节点的动态选取规则, P2P拓扑结构图向拓扑结构表的转换,借助于节点拓扑结构表实现P2P系统任意层次的NAT穿越。最后通过实验验证了多层NAT穿透解决方案的可行性。     

高性能集群计算机的构建与应用

文章分别从软件和硬件两个角度出发介绍了集群系统的体系结构,着重讨论了集群系统构建中的一 些关键技术,如可扩展性、可用性、资源管理、负载平衡和并行程序设计环境等。此外,文中还给出了一个基于消息传递机制的并行程序设计实例,同时也根据集群系统的特点提出了它在不同领域中的实用意义。     

Building a Quantum Network: How to Optimize Security and Expenses

Quantum key distribution (QKD) is regarded as a key-technology for the upcoming decades. Its practicability has been demonstrated through various experimental implementations. Wide-area QKD networks are a natural next step and should inherit the selling point of provable security. However, most research in QKD focuses on point-to-point connections, leaving end-to-end security to the trustworthiness of intermediate repeater nodes, thus defeating any formal proof of security: why bother outwitting QKD, if the repeater node is an easy prey, and an equally valuable target? We discuss methods of designing QKD networks with provable end-to-end security at provably optimized efforts. We formulate two optimization problems, along with investigations of computational difficulty: First, what is the minimal cost for a desired security? Second, how much security is achievable under given (budget-)constraints? Both problems permit applications of commercial optimization software, so allow taking a step towards an economic implementation of a globally spanning QKD network.     

分布与并行处理学术会议论文集高性能集群计算机的构建与应用

文章分别从软件和硬件两个角度出发介绍了集群系统的体系结构,着重讨论了集群系统构建中的一些关键技术,如可扩展性、可用性、资源管理、负载平衡和并行程序设计环境等.此外,文中还给出了一个基于消息传递机制的并行程序设计实例,同时也根据集群系统的特点提出了它在不同领域中的实用意义.     

组建安全可靠、低成本的邮件系统

本文针对一些中小型的企业,介绍了利用动态域名解析技术在linux平台上搭建具有smtp认证、反垃圾邮件及杀毒功能的安全、可靠、价格低廉电子邮件系统的方法.     

SCO UNIX上Web服务器的安装、配置与管理

ＳＣＯ ＵＮＩＸ是目前市场上最为流行的商用ＵＮＩＸ版本。本文利用安装在微机上的ＳＣＯ ＯｐｅｎＳｅｒｖｅｒ５．０５,采用手动和程序两种方式来安装、配置和管理Ｗｅｂ服务器,并详细分析了ＳＣＯ ＵＮＩＸ下的Ｗｅｂ服务器的安装、配置和管理机制。