HN user
The Spanish intelligence service has deciphered the code again since they have found a letter used by the great captain. They have found a "rosette stone" with the code encrypted and deciphered.
http://www.rtve.es/alacarta/videos/telediario/td2-codigo-020...
The secret code of the letters of the Great Captain and Fernando the Catholic that the CNI and the Army Museum announced yesterday to have deciphered, had already been discovered previously. Gustave Bergenroth, a nineteenth-century German Hispanist based in England, published his studies on the General Archive of Simancas in the 'Calendar of State Papers, Spain, Volume 1, 1485-1509' in the year 1862. In the preface he explains his journey in the archive and an introduction to how he deciphered the Spanish codes.
https://www.elconfidencial.com/cultura/2018-02-03/codigo-sec...
A known mistery