972Unsolved Historical Ciphers
Republished copy of Daniel Bourdeau’s Unsolved Historical Ciphers, released under CC BY 4.0. Text unchanged; hosted by JIC alongside its translations; not an official copy by the author · View the original ↗
dom pud · vera · por la capitulacion · ho · nuf · gad · suf
vuestra magestad · vera · por la capitulacion · que · no · se · ha

Venice → Charles V · homophonic alphabet with a three-letter nomenclator · May–August 1523

Alonso Sánchez at Venice to Charles V, May–August 1523

Charles V
toCharles V

Real Academia de la Historia, Madrid, Colección Salazar y Castro 9/28 (A-28), ff. 18–574; DECODE R9670, R9671, R9672, R9674, R9677, R9689, R9690, R9767, R9769, R9770. The catalogue listed these as ten ciphertexts with no decipherment, to an unknown recipient. They are the imperial ambassador’s despatches to Charles V from the months when the Venetian league was negotiated. Their key is Tomokiyo’s reconstruction of Sánchez’s 1522 cipher, applied unchanged. Bergenroth calendared seven of them in 1866 from the contemporary decipherings; one of the three August letters not in the Calendar was deciphered here in part.

Daniel Bourdeau · posted · updated

Method: read with known key · Extent: complete

Summary. The records sit in the Salazar volume that follows the 1522 despatches (Sánchez 1522), and they use the same cipher in the same hand. DECODE flags every one of them “Inline Cleartext: Yes”, but that means passages written in the clear inside the letters; no decipherment was imaged with them. The decipherings made at court do exist, filed elsewhere in the volume. G. A. Bergenroth used them in 1866 for his Calendar of State Papers, Spain, vol. 2. Seven of the ten records are the despatches he calendared as nos. 549 (8 May), 552 (20 May), 554 (5 June) and 558 (13 June), or duplicates of them. The folio numbers match. The other three are dated 16 August 1523, the day after the league was published. They are not in the Calendar, and they are mostly in the clear. The 1522 key (Tomokiyo’s, with this project’s additions) decodes the code groups of every page examined, without change. Deciphered here in part: Sánchez’s own letter of 16 August (R9767). Its clear text is transcribed in full, and in its cipher passages every code group but two is decoded. The spelled letter runs inside them are deciphered only in part. The short cipher head of R9770 is not deciphered.
Folio 563r: the cipher paragraphs of Sánchez’s letter of 16 August 1523, mixed with clear words
R9767, f. 563r (16 Aug 1523). The letter opens in the clear, “Pues por la que en comun escrivimos el prothonotario Caraciolo e yo…”, then moves into cipher. Clear words such as por la capitulacion and ninguna run between the code groups. Image: Real Academia de la Historia, Madrid, Salazar 9/28 (A-28) f. 563r, via DECODE R9767.

01 The ten records

Every letter is headed Sacra cesarea y catholica magestad, so the “unknown recipient” is the Emperor. The dates come from the date lines and from internal references. The matches are by folio and content against Bergenroth’s abstracts, which carry the Salazar A-28 folio numbers.

DECODEff.datecontentCalendar
R967140–438 May 1523the Doge “viejo de noventa años” died on the 7th; Giorgio Cornaro, a commissioner, illCSP 549
R967018–248 May 1523the same letterduplicate of 549
R967278–79c. 20 May 1523refers to the duplicate sent “por via de Genova”; the election of the new Dogecf. 552
R967481–8220 May 1523“es treslado de otro”duplicate of 552
R9677148–152early June 1523“Despues de los xx del passado no he escrito”probably 554
R9689, R9690224–22813 June 1523the Infante’s demands stall the negotiationCSP 558
R9767563–56416 Aug 1523Sánchez alone; two cipher passagesnot calendared
R9769569–57116 Aug 1523Caracciolo and Sánchez; almost all clearnot calendared
R9770572–57416 Aug 1523duplicate of R9769 (“es treslado de otro”), with a clear note on the mutua restitucion instrumentnot calendared

02 The key

The cipher is the one Sánchez used in 1522. Satoshi Tomokiyo reconstructed it in 2025 from a letter with its decipherment attached, and the 1522 write-up extended it. It has an alphabet of cursive signs whose shapes are not their values, three nulls opening each paragraph, and a nomenclator of consonant–vowel–consonant groups assigned in alphabetical order of the plaintext. On R9670, R9671, R9672, R9677 and R9767 the groups decode coherently with that key and nothing contradicts it: xig de, vog en, ho que, nuf no, dom pud vuestra magestad, vum … lal esta [re]publica, gub rac señor infante, tum frances. The ambassador did not change his key between the two volumes.

03 Sánchez to Charles V, Venice, 16 August 1523 (R9767)

Notation: […] marks a code group decoded with the key and ‹…› a spelled run deciphered tentatively; … is not deciphered.

Pues por la que en comun escrivimos el prothonotario Caraciolo e yo vera vuestra magestad todo lo que occorre, no dire en esta salvo que recebi la de vuestra magestad de xv del passado, y quanto … aunque a dezir a vuestra magestad verdad [en el … se con … que no es … frances]. Pero espero en dios que poco podra danyar, aunque es bien toda via [en …].

Vuestra magestad vera por la capitulacion [que no se ha] ‹expressa›[do] ninguna … [por que da lo de esta] ‹re›[publica el di]‹nero› a [vuestra magestad] … [no se … haui … de da]‹r› [mas] … [lo ver]‹e› [vuestra magestad] … [de vuestra magestad].

Pareciendo nos lo mismo que vuestra magestad escrive, no quisimos obligar al señor Infante a la liga defensiva, pues estos no querian obligarse contra el turco. Lo de la navegacion para los subditos del archiducado de Austria no se ha podido acabar con estos; estarse han como hasta aqui. … De Venecia a xvj de agosto de mil D xxiij.

The gist is graded M for moderate. Sánchez refers the Emperor to the joint letter and acknowledges the imperial letter of 15 July. He says something in Venice leans French but “can do little harm”. Then he turns to the financial side of the league, the Venetian payment the ambassadors had failed to raise (CSP 566, 577): the capitulation expresses nothing of it. The particulars are in the spelled runs, which are not deciphered. The clear postscript on the defensive league and the Turk, and on shipping for the Archduke’s subjects, is new: neither point is in the Calendar abstracts.

04 What remains open

05 Sources

Notes, the record table, Bergenroth’s abstracts and the decipherment are in targets/sanchez1523/.