History and Modern Cryptanalysis of Enigma's Pluggable Reflector

The development history of Umkehrwalze Dora, Enigma's pluggable reflector, is presented from the first ideas in the mid-1920s to the last development plans and its actual usage in 1945. An Enigma message in three parts, enciphered with Umkehrwalze Dora and intercepted by the British on 11 March 1945, is shown. The successful recovery of the key of this message is described. Modern computer-based cryptanalysis is used to recover the wiring of the unknown “Uncle Dick,” which the British called this field-rewirable reflector. The attack is based on the known ciphertext and plaintext pair from the first part of the intercept. After recovery of the unknown reflector wiring and the daily key, the plaintext of the second part of the message is revealed.     

基于Qt和Ogre3D的机器人学坐标变换虚拟实验室

为满足机器人学学习过程中的实验需求,描述了一个基于Qt和Ogre3D机器人学坐标变换虚拟实验室的设计和使用。本虚拟实验室重点描述机器人学的坐标变换,在虚拟实验中通过实验来表明欧拉角,RPY角,转轴/角度,单位四元数和齐次变换矩阵的关系,并且使用虚拟手段阐述了DH矩阵的空间意义,通过数值计算和虚拟显示详细地解释这些概念的意义。本文描述了这些虚拟实验的使用方法。为了判断此虚拟实验室的有效性,设计了一个教学实验,实验的结果表明虚拟实验可使教学过程更加合理,且表明虚拟实验室在未来机器人学教学中将会扮演重要的角色。     

基于Ogre的三维管线绘制方法的研究与实现

介绍了Ogre的三维管线的绘制方法。介绍了Ogre的特点,重点介绍了管线的三维建模的过程和原理坐标变换和纹理贴图等技术,并对该方法的应用进行了展望。     

Modern breaking of Enigma ciphertexts

“Breaking German Army Ciphers” is the title of a Cryptologia article from 2005, describing the lucky survival of several hundred authentic Enigma messages of World War II, and an account of a ciphertext-only cryptanalysis of a large number of these messages, leaving only a few (mostly short messages) unbroken. After reviewing the work done, and investigating the reasons for both lucky breaks and close misses, the modern ciphertext-only attack on Enigma messages is improved, especially on genuine ones with short lengths and/or many garbles. The difficulties of a proper measure for the candidate’s closeness to a plaintext are clarified. The influence on the decryption process of an empty plugboard and one with only a few correct plugs is examined. The method is extended by a partial exhaustion of the plugboard combined with an optimized hillclimbing strategy. The newly designed software succeeds in breaking formerly unbroken messages.     

THE DUTCH INVENTION OF THE ROTOR MACHINE, 1915–1923

The rotor machine was invented in 1915 by two Dutch navy officers, R. P. C. Spengler and Th. van Hengel, who were working at the Navy Department in the Dutch East Indies. A prototype was built by W. K. Maurits, a mechanical engineer, and tested during the summer of that year on board the flagship of the Dutch Navy in the East Indies on order of the fleet commander Rear Admiral F. Bauduin. Though the Dutch Navy decided not to adopt the device for it prevented the invention from being patented by the original inventors. The Navy could not prevent the rotor machine from being patented, however, by Hugo Alexander Koch—an engineer and businessman working in close collaboration with Arthur Scherbius in Germany—who probably became familiar with the idea through his brother-in-law, Huybrecht Verhagen, a patent attorney working at the firm that had supported the abortive patent application by the original inventors.     

Accounting for polarization in molecular simulation

Polarization plays an important role in the energetics of molecular systems, not the least in biomolecular systems. Most computer simulation studies of such systems do not treat electronic polarizability explicitly, but only implicitly using effective charges, dielectric permittivities or continuum electrostatics methods. Yet, the introduction of explicit polarizability into biomolecular models and force fields is unavoidable when more accurate simulation results are to be obtained. Various ways to account for polarizability in (bio)molecular simulation are reviewed with an eye to striking a balance between accuracy on the one hand and simplicity and computational efficiency on the other. The various choices to be made are listed and discussed. The most promising approach, the so-called Charge-On-Spring type of models, is treated in more detail and applied to liquid water as an example. Its implementation in the GROMOS biomolecular simulation software is sketched.     

基于DVI和FPGA的视频叠加器设计

利用FPGA作为主控单元,以数字视频接口DVI为视频接口、TI公司的TFP401和TFP410为视频信号的编解码芯片、ISSI公司的SRAM IS61LV10248-8TI为存储单元完成视频叠加器的设计。通过该系统,从路图像的非黑像素能够覆盖主路图像相同坐标的像素。     

园林植物竹子3维造型的Fractal方法

论述了用Fractal方法生成竹子等园林植物的理论基础、数据结构及3维造型的具体步骤。     

一般模型2-D系统干扰解耦观测器设计

提出了一般模型2-D系统(2DGM)的观测器关于干扰解耦的条件,并给出了2DGM干扰解耦观测器的两种设计方法和算例.     

实现3D离散点优化三角划分的三维算法

本文系统研究了３Ｄ离散数据的直接三角划分，并解决了与多值曲面相对应离散数据的分片三角划分问题。实现这一算法的关键是将这些与多值曲面相对应的离散数据按有关的特征线分解，慢之转化成较简单的问题分别进行处理。目前，这种分片三角划分算法已在Ｂｅｚｉｅｒ三角曲面插值中取得了良好的效果。