23/06/2021

Transcoding of Message in Code by Napoleon's General (1812)

I read of a partially enciphered letter addressed to Napoleon's general during the Peninsular Campaign (Cipherbrain). It is a dispatch of Clarke, Minister of War in Paris, to General Caffarelli in Spain dated 19 October 1812. Karsten Hansky acquired it at an auction site and described it in "A dispatch from the French Minister of War Clarke to General Caffarelli, the commander of the Northern Army in Spain, from the year 1812" (17.06.2021) (pdf).
The passages in code are short, but the plaintext is attached. The code in use is what wac called "Great Paris Cipher" by the British (see also my article "Great Ciphers of Napoleon's Grande Armée"). It is code table #24 in the archives of the SHD (Service Historique de la Défense) in Vincenne (SHD box 1M-2352).
What is interesting to me is the marginal note including the coded message (apparently) transcoded into another code (#29). From the range of numbers, the code #29 appears to have about the same size as #24, but the number of codegroups is different (that is, there is no one-to-one correspondence between the code groups.)

09/06/2021

More Cipher Letters of Le Tellier

I added references to more letters from Le Tellier's correspondence in "Ciphers Early in the Reign of Louis XIV". They are found in BnF fr.6884, fr.6889, and fr.6891.
I have already reported that the correspondence between Le Tellier and Colbert appears to have switched to two-part code (Le Tellier-Colbert Cipher 2 (DE=13/59~)) between November and December 1650 (though the arrangement is not completely random), and Mazarin also used it in 1650. This time, it was found DE=13/59~ was used by Mazarin as late as December 1652, while Le Tellier-Colber correspondence used a different two-part code (Le Tellier-Colbert Cipher 3 (DE=18^)) in January 1652.