Eavesdropping on the Biafra-Lisbon link – breaking historical ciphers from the Biafran war
Richard Winston Bean, George Lasry, Frode Weierud · Cryptologia · 2020
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.