Abstract Eighty years after the US Army’s Signal Intelligence Service (SIS) cracked PURPLE, the famous WWII-era Japanese cipher machine, there still has been little technical information published about how it was done. This paper offers a detailed description of how SIS could have done it. The techniques described here would all have been available to SIS in their pre-computer era of the early 1940s, and are based on cryptanalysis using plaintext and matching ciphertext. This paper derives the system architecture, determines the sixes and twenties switch tables, shows how to convert them to wiring diagrams, explains how to handle the complication of the plugboards, extends the information that can be mined from the famous patterns in PURPLE data, corrects a deficiency in the usage of the one published algorithm for cryptanalysis of the twenties, and shows that neither the sixes nor the twenties switch tables are unique.

中文翻译：

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破解紫色：Angooki Taipu B 交换表的密码分析

摘要 在美国陆军信号情报局 (SIS) 破解二战时期著名的日本密码机 PURPLE 八十年后，关于它是如何完成的技术信息的公布仍然很少。本文详细描述了 SIS 如何做到这一点。此处描述的技术在 1940 年代早期的计算机时代之前都已被 SIS 使用，并且基于使用明文和匹配密文的密码分析。本文导出系统架构，确定 6 位和 20 位开关表，展示如何将它们转换为接线图，解释如何处理插件板的复杂性，扩展可以从 PURPLE 数据中的著名模式中挖掘的信息，更正使用一种已发表的算法进行密码分析的缺陷，