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数学代写|密码学与系统安全代写Cryptography and System Security代考|CMSC456 The Mother of Invention

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数学代写|密码学与系统安全代写Cryptography and System Security代考|The Mother of Invention

Machine ciphers were vulnerable. Frank Rowlett (Figure 9.1) and his colleagues knew this, but Rowlett was not tasked with inventing a superior machine; William Friedman thought that he had already created one, namely the M-134. In 1934, Friedman assigned Rowlett the job of simply creating the paper tape keys (Figure 9.2) that needed to be fed through Friedman’s device. ${ }^2$ The key on the tape would control which rotor(s) turned at each step, thus avoiding the regularity of the turning in other machines, such as Enigma. Fortunately, creating the key tape was a horrible job, made even worse for Rowlett by the fact that Friedman told him to spend half of his time at it, while the other half was to be devoted to his continued training, which he much preferred. ${ }^3$

Friedman showed Rowlett how to operate the equipment to make the tape and observed him making a test run. He then suggested Rowlett make several more test runs and left the room Rowlett related what came next:
After he departed, I continued as he had proposed. I decided that I would duplicate the test run I had made under his supervision to see if the keys prepared on two separate runs were identical as they should be. When I finished the second run and compared the two keys, I found several points of discrepancy. I decided that I would make another attempt to duplicate the first run. When it was finished and I compared it with the two previous runs, I found all three to be different. And when I tried two more duplicate runs, I found that I got different results for each. At this point I decided that I had better consult with Friedman.

When I showed Friedman the results I had obtained, he came with me to the equipment room. When he tried to produce a duplicate of the test run I had made, he also obtained different results. We spent until lunchtime trying to get satisfactory results, but with only moderate success.

My first day’s experience with the equipment was only a preview of the succeeding days. The equipment operated erratically, and frequently I had to dismantle a piece in order to locate the trouble. After pursuing this course for some time, I was finally able to make several runs with identical results. By the end of the first month I had completed only a small portion of the compilation task that I had been assigned.

数学代写|密码学与系统安全代写Cryptography and System Security代考|Making the Rotors

Rowlett is not the only hero in this chapter. Someone had to come up with the idea of SIGABA, but that was not enough. The 10,060 machines had to actually be built. Because SIGABA was a rotor-based machine, an extremely important detail in each machine was the wiring of the rotors. If just one wire was soldered incorrectly, that machine would be useless, with potentially disastrous consequences in the field. So, before getting into the details of how exactly SIGABA worked, it’s worth taking a closer look at the rotors and how they were manufactured. Figure $9.3$ shows a SIGABA rotor before the wires were soldered to connect the letters on its opposite sides.

Originally, male shipyard electricians did all of the soldering work. The average production rate for these men was seven rotors per day. ${ }^{10}$ Later, women got a turn to try their hands at this task (Figure 9.4). On the Navy side it was WAVES (Women Accepted for Volunteer Emergency, and for the Army WACs (Women Army Corps). ${ }^{11}$ They worked far faster than the men:
In 1943 the average WAVE managed to solder the connections for fourteen wheels per day. One actually assembled a record twenty-two wheels on her shift. ${ }^{12}$
This rate was attained without sacrificing accuracy:
Midway through the war, the Navy women alone had wired more than 150,000 rotor wheels. Remarkably, there was not a single configuration error and only one instance where a wheel had been mislabeled!!

数学代写|密码学与系统安全代写Cryptography and System Security代考|Making the Rotors

1943 年，WAVE 平均每天能焊接 14 个轮子。一个人实际上在她的轮班上组装了创纪录的二十二个轮子。12

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。