972Unsolved Historical Ciphers
Φ s 7 ℓ ∂ ς ξ R 7 n o b θ ξ x n Ⓜ δ k …
key not found: 56 signs of 29 kinds

Toledo → Montmorency · cipher of graphic signs · 5 January 1526

Gilbert Bayard to Anne de Montmorency, 5 January 1526

Anne de Montmorency
toAnne de Montmorency

BnF, Clairambault 325, f. 84 (DECODE R2285): a seventeenth-century copy of a letter from the French embassy negotiating Francis I’s release. Three lines in the middle of the letter are in cipher.

The cipher was transcribed from the DECODE images and tested against the two French keys of the same months. The printed edition was checked. No plaintext was obtained, and no earlier decipherment is known.

Daniel Bourdeau · posted · updated

Method: not solved · Extent: text not obtained

Summary. Neither Tomokiyo nor DECODE gives a decipherment of this passage, and none is known. The writer is Gilbert Bayard, secretary of the King and élu of Bas-Auvergne. He was one of the French negotiators at Toledo, not a relative of the Chevalier Bayard. The letter was printed in 1847 by Champollion-Figeac (Captivité du roi François Ier, no. CCXVIII), from another copy, and the cipher was simply left out. The marginal note in the Clairambault copy, which DECODE and Tomokiyo describe as irrelevant to the cipher, is a line of the letter that the copyist skipped and then restored; Champollion’s text has it in the body. The 56 cipher signs use the same pool of shapes as Raince’s 1526 key and Calvimont’s alphabet from the same volume, but neither key’s values fit. A ciphertext-only solver (simulated annealing) does not settle on one solution. Status: not solved. It needs the original letter, whose signs will be cleaner than the copyist’s and which may carry a decipherment, or another Bayard letter in the same cipher.

01 The letter

Three lines of the copy: 'celuy de Ferrare a Calatheu' followed by rows of cipher signs, then 'comme j'espere vous dire dimenche'
Clairambault 325 f. 84r, lines 16–19: “…celuy de Ferrare a Calatheu”, the cipher, then “comme j’espere vous dire dimenche”. Image: Bibliothèque nationale de France, Clairambault 325 f. 84r, via DECODE R2285.

The copy is headed “Lettre de M. Bayard a M. le Mal de Montmorency”, dated “5 Janvier 1526”, with the source reference “V. 41. f. 4” in the margin. It is signed “Gilbert Bayard”, “A Tollede le ve jo. de Janvier”. It reports Bayard’s talks with the viceroy Lannoy, with Lallemant and with Don Hugo de Moncada on the four points still open before the treaty of Madrid: the hostages, Fuenterrabía, and the sovereignty of the Constable of Bourbon.

The cipher comes where Bayard tells how the Imperial side had asked whether he had spoken to any Italian ambassador: “…et qu’il y avoit neuf moys que je n’avoye salué celuy de Ferrare a Calatheu [cipher] comme j’espere vous dire dimenche.”

02 The cipher

There are 56 signs of 29 kinds (measured on signs.txt): Greek-like letters (Φ, θ, ξ, φ, γ, ω, ∂), figures (7), Latin letters (n, o, R, b, x, k, e), triangles filled and open, a barred I, a circled m, and an m with a superscript m. With 29 kinds in 56 signs there must be homophones, nulls or code signs. Several of the shapes (7, R, n, θ, x, Δ, ε, ω, and the “ny” and K signs that are nulls in Raince’s key) belong to the pool used by French ciphers of 1525–26. The copyist drew them by imitation, so small differences between shapes may not be meaningful.

03 What was tried

04 What would finish it

05 Sources

Transcription, solver scripts, notes and profile: targets/bayard1526/.