A “Mirror for All Traitors”. Captured Ciphertexts from a Portuguese Spy in Dutch Brazil (1646)

Abstract

A deciphering report found in the National Archives at The Hague presents an intriguing story. A Portuguese spy inside the walls of Recife gathered information about the Dutch defences and wrote it in encrypted letters addressed to the Portuguese rebels that besieged the heart of the Dutch West India Company (WIC) administration in Brazil. The encrypted letters were delivered to the Dutch authorities, who summoned a Jewish cryptanalyst to read them. The report of Abraham de Pina contains a detailed description of the process he used to decipher these letters and presents the complete content of all four ciphertexts. In this paper, we will reconstruct the events of this case and analyze the design of the nomenclature cipher used by the Portuguese rebels. We also will present the flow of information of these intercepted letters within the WIC in Brazil and between them and their company superiors, the Gentlemen XIX, in the Netherlands.