Abstract

The Biafran War, or Nigerian Civil War from 1967 to 1970 was a significant conflict in post-colonial African history. We obtained encrypted messages sent from Lisbon to Biafra via telex during the conflict. We employed manual and computerized cryptanalysis methods to decipher a series of transposition ciphers sent by Biafran officials in 1968 and 1969, which were encrypted using unknown variants of columnar transposition. We then derived the keywords the system was based on and the method used, and analyzed the codewords, names and traffic contained in the plaintexts. Some five-figure ciphers sent during the same period remain unsolved.

摘要

1967 年至 1970 年的比夫拉战争或尼日利亚内战是后殖民时代非洲历史上的一场重大冲突。在冲突期间，我们获得了从里斯本通过电传发送到比夫拉的加密信息。我们使用手动和计算机密码分析方法破译了 Biafran 官员在 1968 年和 1969 年发送的一系列转置密码，这些密码使用未知的柱状转置变体进行加密。然后我们推导出系统所基于的关键字和使用的方法，并分析明文中包含的码字、名称和流量。在同一时期发送的一些五位数密码仍未解决。