光纤传输通信系统保密技术研究

由光的传播特性可知,光的波长短、频率高,所以在利用光纤进行通信时,通信系统的传输带宽很宽,有利于数字通信的应用。这样不仅数字通信信号不容易被敌对势力窃听,还可以对数字信号进行加密。另外,利用光纤进行信息传输时,不会产生电磁场和信号的泄露,保密性极强。但是随着技术的发展与进步,对光纤通信线路进行窃听也成为一种可能,因此,对光纤通信网络的保密技术进行研究也就引发了业界的极大关注。本文介绍了混沌保密技术、光纤码分多址保密技术、量子通信保密技术,并阐述了三种保密技术的原理以及技术特点,供我国专用通信网络未来的保密防护参考。     

基于OCDMA over WDMA的光纤网络

基于OCDMA在网络扩张方面的优势,本文考虑采用相干OCDMA方法,提出了OCDMA over WDMA光网的结构,并对其网络特性、连接协议、优点及其在光网络中应用时系统出现的问题加以讨论。最后通过计算机仿真,研究了OCDMA over WDMA网络的阻塞特性与时间延迟。     

基于OPS技术的超高速光孤子通信实现方案

通过对光分组交换(OPS)技术的讨论,实现了多交换节点的超高速光孤子通信传输方案.在详细阐述光孤子通信系统中光分组形式和OPS节点结构的基础上,进一步分析了传输方案实现的可行性,最后对该技术的优劣进行分析.指出,基于OPS技术的光孤子通信是实现未来全光网的首选.     

采用OCDMA技术的全光网

提出了在未来全光网中采用OCDMA技术的实现方案。OCDMA可以和WDMA相结合,细化光交叉连接的颗粒,增强光通道层的灵活性,而且可以直接从现有网络升级;OCDMA还可以和OTDMA相结合,实现信令的全光处理和的帧定界,从而使OTDMA网无需复杂的同步,这将为光包交换的实现提供一种有效的手段。进一步的研究需要对全光网节点内的交换网络结构和路由协议进行深入考虑。     

略论JTIDS通信保密技术

自美军的ＪＴＩＤＳ系统在海湾战争中成功使用后，世界各国对其倍加重视。我国有关部门对此也十分重视并已开始做了些研究工作。本文将在概述ＪＴＩＤＳ系统的技术特性和发展状况基础上，着重限于ＪＴＩＤＳ系统的通信保密技术部分，向有关人员作些介绍和简要分析。     

瑞士保密通信技术现状

瑞士保密通信技术现状瑞士有三个主要保密通信设备制造商：Ｇｒｅｔ。ｇ、ＣｒｙｐｔｏＡＧ和ＢｔＯＷｎ＆ＢＯｙｅｒｉＣＯ（现改名为ＡＣＣ）。ＡＣＣ最早出现在美国市场上。它长期专门生产数字话音置乱器。该公司生产的话音置乱器和数字话音加密机是世界上最普及的种类...     

保密通信与CSD在GSM保密通信中的应用

本文主要讨论了保密通信的概念、数据加密的方式、加密的算法及密钥管理方式,描述了一种利用CSD信道来实现GSM网络中的数字加密通信方式。     

一种真正的全双工电话保密通信技术

几乎所有的电话保密系统都使用回波抵消技术来实现全双工通信，不幸的是，由于受实际电话信道特性的影响，该技术至今尚未完全解决这一双全双难题，本文在此介绍一种改进方法，实验表明，使用该方法，可获得类似明话的全双工通信效果。     

Comparison of surface- and edge-emitting LED's for use in fiber-optical communications

The performance of state-of-the-art double-heterojunction (DH) surface and edge emitters are compared with respect to their use in high-data-rate fiber-optical communication systems. Thick-window (20-25-µm) surface emitters with 2-2.5-µm thick active layers and emitting up to 15-mW optical power at 300 mA have been fabricated. For edge emitters, we use very-high-radiance-type devices with ≃ 500-Å thick active layers. For these two types of LED's we examine differences in structure and light coupling efficiency to fibers of various numerical apertures (NA). For typically good devices we compare the diodes' output power capabilities, the powers coupled into step- and graded-index fibers of various NA, and their respective frequency response. For the same drive current level, we find that edge emitters couple more power than surface emitters into fibers with NAlsim 0.3. The edge emitters also have ≈ 5 times larger bandwidths. We estimate that an edge emitter can couple 5-6 times more power into low numerical aperture (NAlsim 0.2) fibers than a surface emitter of the same bandwidth. We conclude that edge emitters are preferred to surface emitters for optical data rates above 20 Mbits/s.     

Secure communications by optical homodyne

It is shown that optical homodyne techniques offer a family of schemes for secure communications. Following some background in secure optical communications, a particular scheme is described and compared to cryptography. The scrambler built is also described, and security is discussed. Experimental results for point-to-point links in single-mode polarization-maintaining fibers are presented. Various enhancements and network compatibility are analyzed     

802.6 MAN based personal communications network over CATV plants

An infrastructure shared 802.6 MAN based personal communication network(PCN) is to be discussed. Considering the network configurations of CATV and 802.6 MAN based PCNs, a possible architecture is proposed. It is shown that the unidirectional dual buses can be implemented over star topological CATV distribution cable networks with only two cores. The design considerations related to the network capacity and the signaling loads for wireless personal communications are investigated with numerical example. The MAN partitioning is considered to extend the capacity of the network. An analytical method to evaluate the signaling loads of 802.6 MAN based PCNs is presented with a new mobility model. It is shown that the signaling traffic increased by partitioning is not the critical constraint for the feasibility of 802.6 MAN based PCN     

Planning a business communications network

The process of planning user networks that carry both data and voice, and possibly other media such as facsimile and video, between a number of computers located throughout the country and a variety of terminals and PCs among a large number of employees is discussed. A team consisting essentially of customer systems engineers from the telephone company, similar persons from the computer equipment supplier, and contacts in the user's communication department is used to illustrate the process; however, the approach works equally well with teams consisting of another appropriate mix. The factors considered include cost effectiveness, performance, maintainability, survivability, and network management. The networking aspects and their impact on the operating environment of the user are considered     

Distribution of electronic mail over the broad-band party-line communications network

Cable television (CATV) is unique in that it is the only wire, besides telephone, with potential access to 80 million customers. Many new services have been proposed to utilize this access-from meter reading to transmission of an entire book in seconds. The author postulates that electronic mail is the market CATV should pursue and describes the market potential, a system design in some detail, and an estimate of the costs involved. An intriguing result of this analysis is the possibility of sending mail electronically for only 10 cents a letter.     

Secure group communications using key graphs

Many emerging network applications are based upon a group communications model. As a result, securing group communications, i.e., providing confidentiality, authenticity, and integrity of messages delivered between group members, will become a critical networking issue. We present, in this paper, a novel solution to the scalability problem of group/multicast key management. We formalize the notion of a secure group as a triple (U,K,R) where U denotes a set of users, K a set of keys held by the users, and R a user-key relation. We then introduce key graphs to specify secure groups. For a special class of key graphs, we present three strategies for securely distributing rekey messages after a join/leave and specify protocols for joining and leaving a secure group. The rekeying strategies and join/leave protocols are implemented in a prototype key server we have built. We present measurement results from experiments and discuss performance comparisons. We show that our group key management service, using any of the three rekeying strategies, is scalable to large groups with frequent joins and leaves. In particular, the average measured processing time per join/leave increases linearly with the logarithm of group size     

Secure key agreement for group communications

A secure key agreement protocol for group communications is proposed in this paper, which ensures the authenticity of group members and the privacy of group messages, and provides the properties of perfect forward and backward privacy. In a group session, the common key is collaboratively established by all participants, hence the overhead of key agreement is balanced among group members. Copyright © 2001 John Wiley & Sons, Ltd.