PDM系统安全及图档管理的关键技术

【作者】 陈平；

【导师】 刘钊；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2003， 硕士

【摘要】 本文介绍了为某单位研制的PDM（Production Data Management，产品数据管理）系统，它是一个以现代项目管理为核心，针对军工电子产品设计行业来开发的企业信息集成处理系统，以下简称X-PDM。本文的主要内容涉及X-PDM系统的安全服务及其实现方案的设计，以及图档管理关键技术之电子电路原理图自动输入与理解系统的研究。本文同样介绍了X-PDM的特点和系统框架，以及作者完成的系统管理部分的工作。首先在第一章中简单介绍了整个X-PDM研制背景，介绍了国内外PDM技术的发展状况，提出X-PDM系统的设计思想，并对X-PDM的系统结构和它所运行的网络硬件结构作了简单的介绍。第二章介绍基本的应用密码学算法和密码协议，包括对称加密算法、非对称加密算法、散列函数、数字签名技术和密钥管理协议。这些算法和协议构成了现代信息安全技术的基础。本章中还列举了DES、RSA、MD5，等目前已经得到广泛使用的几种成熟算法，也讨论了这些典型算法的安全性。第三章介绍X-PDM安全方案的设计工作。X-PDM是基于分布式多层结构开发的，这种架构也是PDM技术的主要发展方向。作者以ISO7489-2为基础，针对分布式三层结构的安全隐患，将X-PDM的安全服务类别重新描述为鉴别、访问控制、数据安全、抗否认等4类。基于用户管理技术，综合运用各种加密技术和密码学协议，提出了一套完整和实用的安全服务实现方案。方案主体包括应用服务器连接鉴别、数据服务器连接、传输加密和管理员防范四个方面。该方案在X-PDM上得到了实现。本章的最后还介绍了系统管理模块的主要功能、模块流程和接口关系。第四章详细介绍了电子电路原理图自动输入与理解系统的设计过程，它是X-PDM图档管理的核心技术，主要用于企业电子电路原理图纸的归档工作。这一系统的主要任务是理解图纸中的字符、导线、元器件符号和它们的相互关系，最终实现元器件汇总和图纸清书。首先对图纸的光栅图像进行字符分离，利用均匀网格方法抽取字符特征，用BP神经网络进行训练和识别。在利用特征点提取方法对元器件符号进行识别之外，作者还提出利用句法模式识别方法识别元器件符号，做了试探性的研究。最后将字符、导线和元器件符号三元素有机结合，得到输出结果。更多还原

【Abstract】 The dissertation makes a presentation of the research and development of PDM (Production Data Management) system. We call it X-PDM in the following. X-PDM takes modern project management as its core, and aim at the trade of electronic products designing for army.The main topic of the thesis is talking about the security services of X-PDM, the realization of the security scheme, and the automatic understanding for electronic circuit schematic drawings, which is the key technology of document management in X-PDM. The characteristic, the system structure and system management module of X-PDM are also mentioned in the thesis.First in chapter one, we introduce the background of X-PDM system and the development of PDM technology. We propose the frame of the whole system and introduce the X-PDM system structure and the network that it runs on.In chapter 2, the basic algorithms and protocol of applied cryptography are introduced here, including symmetric-key cryptography, public-key cryptography, hash functions and key management protocols. The algorithms and protocols are the base of modern information security technology. Kinds of typical algorithms widely used are listed, such as DES, RSA and MD5, and we also discuss the security of them.In chapter 3, we describe the research and development of X-PDM security scheme. Distributed Multi-tiers Architecture is the way that PDM are focusing on. X-PDM is constructed on this architecture. Comparing with ISO7489-2, aiming at the hidden troubles of the distributed 3-tiers architecture, we redefine the security services of X-PDM into 4 classes, which are authentication, access control, data security and anti-repudiation. Based on user management, kinds of cryptography algorithms and protocols, an integrated and applied realization of security service is proposed. The principal parts of the scheme include<WP=6>application server access authentication, database server access authentication, secure communication, and administrator attack prevention. The scheme is already realized in X-PDM. At last, we also introduce the main functions, module flow and relationship between interfaces of system management module.In the last chapter, the automatic understanding system for electronic circuit schematic drawings is introduced. It is a key part of X-PDM document management. The main task of it is to recognize 3 kinds of element inside the drawings, including characters, components and also the topologic of the whole graph. And finally, count out the kind and the number of each component symbols, and redraw the circuit schematic drawing. After characters are divided from the raster image, the features of characters are extracted by symmetrical grids and then are inputted into BP neural network for further analysis. For components, we use the means of feature extraction and also propose Structural Pattern Recognition to recognize them. After all 3 kinds of elements being recognized, they are well organized to form the final result.更多还原