In The ciphers of Czechoslovakia’s government in exile I’ve added the following in the paragraph ‘Report on the compromise of the communications of the government in exile’:
The report ‘Dopady lúštenia šifrovacieho systému čs. londýnskeho MNO z rokov 1940-1945 na domáci odboj’, can be found in the archive of the Museum of the Slovak National Uprising in Banská Bystrica and in the Central Military Archive at Prague.
In the report Cigan analyzed the Czechoslovak STP cipher and found it insecure. In addition he proved the compromise of Czechoslovak ciphers by examining reports from the office of the high ranking SS official Karl Hermann Frank.
A report from November 1944 had a summary of Funkwabwehr (Radio Defense) operations and it said that during the previous month 8 radio links, whose cipher procedures could be solved, were kept under observation. Of special interest was traffic between the Protectorate and London regarding the preparations for the uprising.
In the month of October a total of 488 messages were solved and 8 cipher keys derived for the STP cipher.
In pages 37-41 Cigan directly compared the Funkawbehr decodes with some of the Czechoslovak telegrams found in the country’s national archives.
For example messages exchanged between the Minister of National Defense General Ingr and Ján Golian and Jaroslav Krátký in the Protectorate and with Heliodor Píka in Moscow.
The author’s conclusion was that the use of insecure ciphers during wartime played an important role in undermining the operations of the Czechoslovak resistance movement and these events should be acknowledged by the country’s historians