浅谈压缩软件在水利行业中的应用

文章对压缩软件在使用后的一点心得体会作出简要介绍，并总结了这些压缩工具在压缩过程中的注意事项，以及其对本行业中水利工程图的影响。     

用WinRAR实现数据的自动备份

运用WinRAR的命令行参数,可简化操作过程,实现数据的自动备份.     

基于多核FPGA的压缩文件密码破译

目前,破解WinRAR传统方法是使用CPU和GPU,而潜在的密码空间非常大,需要更高性能计算平台才能在有限的时间内找到正确的密码。因此,采用四核FPGA的硬件平台,实现高效能的WinRAR破解算法。通过在全流水架构下增加预计算和保留进位加法器结合的方法优化SHA-1算法,提升算法吞吐率;利用状态机的控制优化数据拼接,提升算法并行性;同时,采用异步时钟和多个FIFO缓存读写数据优化算法整体架构,降低算法内部的耦合度。实验结果表明,最终优化后的算法资源利用率为75%,频率达到200 MHz,4 位长度的密码破译速度为每秒102 796个,是CPU破解速度的100倍,是GPU的3.5倍。     

数据多次分组的图像无损压缩算法

对经典的图像无损压缩方法进行了比较全面的分析和研究。提出一种利用图像相邻像素之间的相关性对数据进行多次分组压缩的图像无损压缩算法,并提出了四种处理相同像素值或相近像素值的RLE改进算法和一种针对二值序列的长度编码表压缩算法,取得了较好的压缩效果。实验结果表明本算法的压缩比优于WinZIP,与WinRAR基本相当。     

基于逆向工程的WinRAR密码恢复研究

WinRAR作为目前应用最广泛的功能强大的压缩包管理软件,采用密码加密方式保护数据并具有很高的安全性,这使得WinRAR的密码恢复十分困难。目前主要的恢复方式都是采用暴力恢复,但是由于WinRAR的密码判定流程运算量大,暴力恢复的效率十分低下。利用逆向工程技术对WinRAR3.x的文件加密机制进行了分析,并得出WinRAR3.x的密码处理与验证流程,在此基础上进行了流程优化,使验证过程中执行的AES运算次数减少到2次,大大降低了密码恢复过程中的AES运算量。优化后的算法程序更加精简与高效,尤其对大文件的密码恢复有非常好的效果。     

On the security of the WinRAR encryption feature

Originally written to provide the file compression feature, computer software such as WinRAR and WinZip now also provide encryption features due to the rising need for security and privacy protection of files within a computer system or for sharing within a network. However, since compression has been much in use well before users saw the need for security, most are more familiar with compression software than they are with security ones. Therefore, encryption-enabled compression software such as WinRAR and WinZip tend to be more widely used for security than a dedicated security software. In this paper, we present several attacks on the encryption feature provided by the WinRAR compression software. These attacks are possible due to the subtlety in developing security software based on the integration of multiple cryptographic primitives. In other words, no matter how securely designed each primitive is, using them especially in association with other primitives does not always guarantee secure systems. Instead, time and again such a practice has shown to result in flawed systems. Our results, compared to recent attacks on WinZip by Kohno, show that WinRAR appears to offer slightly better security features. Gary S.-W. Yeo completed his B.Eng in Electronics & Computer Systems in the first half of 2005, and is currently working as an electronics engineer with a semiconductor fab facility. Raphael C.-W. Phan is currently Director of the Information Security Research (iSECURES) Laboratory at the Swinburne University of Technology (Sarawak Campus) – SUTS, Kuching, Malaysia. Raphael researches on cryptography, cryptanalysis, authentication and key exchange protocols, smart card security, hash functions and digital watermarking. His work has been published in refereed journals published by IEE, IEEE, Elsevier Science and US Military Academy; and in internationally refereed cryptology conferences published by Springer-Verlag, Germany. He is referee for several IEEE journals on the area of information security. He is General Chair of Mycrypt '05 and Asiacrypt '07, Program Chair of the International Workshop on Information Security & Hiding (ISH '05), and technical Program Committee member of Mycrypt '05, the International Conference on Information Security & Cryptology (ICISC '05) and International Conference on Applied Cryptography & Network Security (ACNS '06).     

动态网页中在线压缩与解压缩

本文介绍了在Windows自带的WSH脚本环境中，利用winrar．exe及cmd．exe命令文件实现动态网页中的在线压缩与解压，并列举了部分参考例子，最后给出了较完整的实现代码。     

用WinRAR实现数据的自动备份

运用WinRAR的命令行参数,可简化操作过程,实现数据的自动备份。