Friday, December 13, 2013

The Pope’s codes

                                                 The Pope! How many divisions has he got?
                                                                                 Joseph Stalin
Although the Pope doesn’t have any divisions he has always been one of the most powerful men on the planet. As leader of the Catholic Church and head of the Vatican State he can wield great influence on world affairs.

With millions of followers all over the globe the Catholic Church has traditionally been well informed of world events. The numerous Catholic churches with their priests, bishops and other officials have always transmitted information back to the Vatican. In order to protect its communications from outsiders the Catholic Church has used various cryptologic systems.
During WWII the communications of the Vatican attracted the attention of numerous codebreaking agencies. Both the Axis and the Allies tried to exploit these messages and they succeeded, in part.

German effort:

Three different agencies worked on Vatican codes. The German High Command’s deciphering department – OKW/Chi, the Foreign Ministry’s deciphering deparment Pers Z and the Air Ministry’s Research Department - Reichsluftfahrtministerium Forschungsamt.
The Germans spied on the Catholic Church because they knew that the internal opposition to Hitler and the Polish intelligence service had connections with the Vatican.

Unfortunately the information on their successes and failures versus Vatican systems is limited.

European Axis Signal Intelligence in World War II, vol3 says in page 69:
Around the beginning of the war, a desk was established for attacks on Vatican traffic. Seifert, a former member of the Austrian Cryptanalytic Bureau, joined OKW/Chi at the time of the Anschluss and broke a Vatican book.

Pers Z
European Axis Signal Intelligence in World War II, vol6 says in page 33:

The 1940 Report of the Italian Group (Paschke) made it clear that while approximately 50 per cent of the Vatican traffic could be read, the traffic was not a major Pers Z S commitment. Reference was made to a one part, three-letter code, enciphered by a transposition within the groups, and to a one-part figure code, enciphered by means of substitution alphabets and a sliding strip. Most of the book groups were secured from Goering's "Research" Bureau (FA).

It seems that serious work on Vatican cryptosystems was done at Goering’s Forschungsamt. However the information from TICOM reports on the work and successes of the FA is very limited.

European Axis Signal Intelligence in World War II, vol7 says in page 88:
Vatican Code,

In  a captured Pers ZS reconstruction of a Vatican Code Book the signature of a Fraulien Titschak appears with the date of August 1939 and a notation that she had copied out values at that time for the FA (Fraulien Titschak was a member of the Foreign Office Cryptanalytic Bureau). The Annual Report of the Italian Group of Pars ZS for 1940 indicates that while Pers ZS did some work on Vatican systems most or the identifications on Vatican systems were received, from the FA.
Several reports were written in the postwar period by former workers of the FA but these have not yet been declassified by the NSA.

Italian effort:
The Italian Army’s codebreaking department solved Vatican codes during WWI and in the interwar period. According to David Alvarez’s ‘Left in the Dust: Italian Signals Intelligence, 1915-1943’:

Access to Vatican traffic proved a boon to Italian intelligence. Such traffic provided Rome with advance word of papal diplomatic initiatives, such as the pope’s peace proposal of August 1917 and his efforts in 1918 to mobilize Catholic opinion and lobby foreign leaders on behalf of Vatican representation at the peace conference.
However during WWII the small number of cryptanalysts had too many commitments and it doesn’t seem like they could solve the high level Vatican messages.

Finnish effort:
According to David Kahn’s ‘Finland's Codebreaking in World War II':

Among the simplest codes to crack were those of the Vatican. In the 16th century the papal curia led the world in cryptology, and AaIto thought that they had not advanced beyond that level, as described in a couple of studies of nomenclators of that period in a Finnish journal by H. Biaudet in 1910. Vatican codes were attacked by O. Nikulainen because he was the only cryptanalyst who knew Italian. However, the results had little value.

Anglo-American effort:
Information on the efforts of British and US codebreakers versus Vatican codes is available from the article ‘No immunity: Signals intelligence and the European neutrals, 1939-45’.

The British codebreakers solved in 1942-43 parts of the low level code RED, a three-letter code of 12,000 groups enciphered by substitution tables. The information was shared with the US Army’s cryptanalytic agency that assigned a group of codebreakers to tackle Vatican traffic. This section was called ‘Gold’.
Neither the British nor the Americans were able to solve the high level codes used by the Vatican.

According to the article:
The cryptanalysts in Gold Section were surprised at the sophistication of Vatican cryptosystems. Explaining their lack of success, they noted that 'The difficulties encountered showed that considerable intelligence was matched against the analysts', and they concluded that they were dealing with 'a cryptographer of no mean ability.' The effort against papal cryptosystems was also undermined by the complete absence of compromised cryptographic materials and the communication discipline of papal diplomats.’

In the course of WWII the communications of the Vatican attracted the attention of both the Axis and the Allies. Both sides were able to exploit some Vatican cryptosystems but according to the information available, the Pope’s high level codes proved secure.

Perhaps a guardian angel was looking out for the Pope.
Sources: ‘European Axis Signal Intelligence in World War II’ volumes 3,6,7, Intelligence and National Security article: ‘No immunity: Signals intelligence and the European neutrals, 1939-45’, ‘In the Name of Intelligence: Essays in Honor of Walter Pforzheimer’, International Journal of Intelligence and CounterIntelligence article: ‘Left in the Dust: Italian Signals Intelligence, 1915-1943’,


  1. Fascinating work. One of these days I'd really like to dig into how exactly observations from the Catholic Church's global outposts gets transmitted back to the Vatican, and what was being passed up. Thanks for shedding some light!

  2. Nyall Meredith12/13/13, 4:57 AM

    Fascinating to see the contrast between Pentii Aalto's opinion and everyone else's.

    1. It’s obvious that the Finns were referring to the low level systems. That would explain the statement that ‘the results had little value’

  3. Some (or all?) of the British intercepts and decrypts of Vatican communications are catalogued on the Public Record Office Web site,



    Dimitri Cavalli
    Bronx, New York