At a glanceNot solved · text not obtained
- The letter
- Ferdinand, King of Hungary and Bohemia (Emperor Ferdinand III from 1637), to Maximilian von Trauttmansdorff, 13 November 1634. A contemporary copy; a clear passage at the end says Ferdinand put it in cipher and sent it by his own messenger.
- Where
- Státní oblastní archiv v Plzni, pracoviště Klášter u Nepomuka, Rodinný archiv Trauttmansdorffů, karton 6, inv. č. 68. Not on DECODE.
- The cipher
- Not seen. Jakub Mírka, who catalogued it, describes it as two- and three-digit numbers only, probably a nomenclator with homophones, bigrams and code words.
- How it was tried
- A search for any image of the letter, and a check of the one known 1634 key of Ferdinand’s, which uses a different kind of sign.
- Still open
- The whole letter. Scans have to be ordered from the archive; the key may survive in Vienna.
- Credit
- Jakub Mírka found and described the letter (2012); Satoshi Tomokiyo’s list of ciphers with no known decipherment brought it into the catalogue.
01The letter
In November 1634, two months after the victory at Nördlingen, the imperial court was negotiating with the Elector of Saxony at Pirna; the preliminary peace was signed there on 24 November and became the Peace of Prague in 1635. Maximilian von Trauttmansdorff, high steward to the young King Ferdinand and the emperor’s chief negotiator, kept copies of the king’s letters to him. Among them, in the Trauttmansdorff family archive now at Klášter u Nepomuka, is the copy of a letter of 13 November 1634 written in cipher.
Jakub Mírka described it in his 2012 survey of the cipher letters in the noble family archives of SOA Plzeň. It is the only enciphered letter among the copies of Ferdinand’s letters to Trauttmansdorff. A passage in clear at its end says that the king enciphers the letter and sends it by his own messenger, which suggests he thought the matter important. Mírka could not break the key. From the number and form of the signs he judged it a nomenclator with homophones, bigrams and probably code words, and he noted that the cipher alphabet is made up entirely of two- and three-digit numbers. His article reproduces seventeen figures; none of them is this letter.
02What was tried
- An image. The letter is not on DECODE: the full record list (10,106 records) holds only one group from the Trauttmansdorff family archive, the Hamburg letters of Kurz von Senftenau of 1639 (Kurz to Trauttmansdorff). Cryptoole (HUXXXX-1) and Tomokiyo’s list give Mírka’s description only. The 2012 volume of Západočeské archivy is sold in print, and the archive’s library catalogue holds only its cover and contents page.
- Ferdinand’s cipher of October 1634. A letter of Ferdinand’s of 28 October 1634 to the Cardinal-Infante, sixteen days earlier, was partly deciphered here (Ferdinand III and the Cardinal-Infante). Its cipher is made of graphic signs and three-letter codes, not numbers, so it is not the key to this letter.
- Ferdinand’s later ciphers. Barbora Šimsová’s 2024 thesis edits Ferdinand’s cipher letters of 1635–1638 to Matthias Gallas, deciphered at the time; their key does not survive, and the thesis does not mention this letter.
03What remains
- Scans of karton 6, inv. č. 68, every page including the clear ending, from SOA Plzeň (Klášter u Nepomuka).
- Mírka suggests the key may survive in Vienna, in the Trauttmansdorff family archive or the Haus-, Hof- und Staatsarchiv. A numerical nomenclator for Ferdinand’s correspondence of 1634 would let the letter be deciphered as soon as it is seen.
- Without a key, a nomenclator of two- and three-digit numbers needs enough text for a ciphertext-only attack; the letter’s length is not known.
04Sources
- Jakub Mírka, “Raně novověká šifrovaná korespondence ve fondech šlechtických rodinných archivů Státního oblastního archivu v Plzni”, Západočeské archivy 2012, pp. 44–73, notes 37–39 and 135 (volume; ResearchGate).
- Barbora Šimsová, Šifrovaná korespondence Matyáše Gallase s císařem Ferdinandem III., MA thesis, Charles University, 2024 (repository).
- Cryptoole HUXXXX-1; S. Tomokiyo, Cryptiana, open items.
Notes and profile: targets/ferdinand1634/.