BnF Espagnol 318: five ciphered letters of the Catholic Monarchs’ correspondence, 1497–1504

01 The five letters

The volume (ark btv1b52503046q, 486 canvases, 127 folios) is the autograph collection of the Ruffo di Scilla princes, sold in 1854 and bought by the BnF in 1857; Morel-Fatio catalogued it in 1892 as no. 172. Its hundred items are letters to Ferdinand and Isabella from most of the crowned heads of Europe. Five are wholly or partly in cipher. The item numbers are the notice’s; the folio numbers are the volume’s own, and the canvases have to be mapped from the notice because almost every canvas label on Gallica is NP.

No decipherment survives anywhere in the volume for nos. 93, 94 or 95. F. 121v carries the superscription of the viceroy’s letter, Alto y muy poderoso prinçipe Rey y Señor, the wax seal, and a later Spanish endorsement written sideways down the left margin: Del virrey de Siçilia en çifra. That is all anyone in the archive ever said about it.

All five are in one office’s style, described once here because everything below depends on it. A cipher of Ferdinand’s secretariat is two things at once: a homophonic alphabet, three to five invented symbols per letter, and a nomenclator of two-, three- and four-letter groups (consonant, vowel, consonant) written in ordinary Latin letters in the same hand, standing for words, names and syllables. The nomenclator is one-part: the vocabulary runs alphabetically and the groups run in a fixed order beside it, so the initial letter of a group tells you roughly where in the alphabet its plaintext sits. Three such keys of this period are in print or reconstructed, and each uses a different band of initials. That is what makes it possible to say which key a letter is in without deciphering a word of it.

02 No. 5: deciphered in print in 2020

The first check was for an existing decipherment. Searching for the shelfmark rather than the cipher turns up Ivan Parisi, Un cifrario in prestito per una lettera segretissima di Federico d’Aragona re di Napoli ai Re Cattolici nel BnF, Espagnol 318, in Studi di storia medioevale e di diplomatica, n.s. IV (2020), pp. 157–177, open access, DOI 10.54103/2611-318X/14378. It prints the letter entire.

The article’s point is an anomaly. Federico of Aragon, the last Aragonese king of Naples, wrote to Ferdinand and Isabella on 11 January 1497 to confirm a pre-agreement for the marriage of his nine-year-old son Ferrando, duke of Calabria, to one of the Spanish infantas. He had the secret part enciphered in the Spanish ambassador’s cipher, the key issued to Joan Ram Escrivà, who was standing in Naples at the time. Parisi pins the encipherer by a Spanish speaker’s mistake: whoever wrote the cryptogram failed to use the double-s sign in possano, obedientissimo and promesso, an error an Italian would not make and a Spaniard would. So the king of Naples handed his minute to the ambassador, and the ambassador made the fair copy and enciphered it.

The letter’s own first clear line names him (Da poi de havere resposto ad micer Joan Scrivà, oratore de le Maiestate Vostre), the one clue on the leaf that this is a borrowed key. The nomenclator elements Parisi lists are legible on the Gallica image at 3000 px and match the image: qix del, qao duque, qav de, qae con, qed cosa, qie como, rae el, rof en, ru mensajero, saf Italia, sul la, tad no, tay parte, vee que, vet si, vog sobre, xer and xoq Vuestras Altezas, xit una, pam bien. Note the band of initials: p, q, r, s, t, v, x. It will matter in §05.

03 No. 92: the key confirmed against its glosses

F. 116 is headed by its sender, la respuesta q[ue] enbio a los s[eño]res en xbij de ag[osto] 1500, and opens in clear:

Muy mag[nifico] Señor: a los xiiij d[e]l presente recebi v[uest]ra letra con hun breve d[e]l papa y otras dos cartas del embax[ad]or veneçiano con uno suyo, dando priesa en my yda a la resistençia del turco. E porq[ue] esto es conforme a la voluntad e mandami[ento] q[ue] yo tengo de sus al[teza]s, en virtud de Jhu Xpo yo me dispongo a ello con toda la celeridad y presteza q[ue] el caso requiere…

and then alternates clear and cipher for two pages. It is Gonzalo Fernández de Córdoba, the Great Captain, writing to the Lorenzo Suárez of the notice (Lorenzo Suárez de Figueroa, Spain’s ambassador at Venice until his death there in 1506, whose own ciphered letters Galende Díaz lists), about the expedition against the Turk. This is the copy kept for the secretary Miguel Pérez de Almazán. Tomokiyo’s page on the Spanish ciphers notes that the Great Captain “used this cipher” (Ferdinand and Isabella’s general cipher of about 1500–02) in this letter, and lists the letter itself as having no known decipherment.

This could be tested, because a later hand wrote a partial decipherment between the lines of f. 116r. The glossator deciphered a few words and stopped; his words are the control.

Juan Carlos Galende Díaz printed the key in 1994, from a file of twelve ciphers in the Real Academia de la Historia (B.R.A.H. 9/15): his appendix 1 is the Cifra general de los Reyes Católicos, ff. 7–9 of that file. Checked against the glosses, its plates give eight independent matches and no conflict:

A gloss-anchored line then decodes straight through:

ct   h  boy      zez    xiz  7  xuy  baz      ff k …
pt   y  tiempo   por    esta r  en   tanto    p  g …

giving …y tiempo, por estar en tanto…, which is what the glossator wrote above it. F. 116v ends half in clear, and the codes sit inside sentences whose sense is clear without the key: …no desconfio que mucho se pudiera aprovechar … esta var … zin se ha ofreçido … yo me desnudo y descargo y me satisfago en que n[uest]r[o]…, with zin = Nápoles, xar = después, biz = toda, xuy = en. Below that a later inventory hand: Inventº 11 Ottº 53.

So the key of no. 92 is identified, and the rest is transcription and decipherment: the code groups are plain Latin letters and are easy to transcribe, while the alphabet signs have to be matched one by one against a 1994 photocopy of a sixteenth-century table. The key is transcribed here as keys/cifra_general.txt: 683 code groups from the plates (pp. 167–173), plus the twenty-one personal signs: Papa = A, Emperador = B, Rey de Françia = F, Rey de Spanya = G, Reyna de Spanya = 4, Principe de Spanya = C, Rey de Inglaterra = S, Rey de Napoles = □, Duque de Calabria = R, Infanta doña Juana = oTT, Don Fadrique prinçipe de Altamira = S†.

The two pages deciphered (21 September 2026)

Both pages have now been transcribed line by line, 36 lines on the recto and 11 on the verso, against the symbol alphabet Galende prints on p. 167. The hand leans on a few forms the specimen line had not shown: the fifth form of A (a reversed C with a hash) and the fifth form of E (a q with a k written below it) carry most of the vowels, the crossed T is the key’s “duplicate” sign for LL (vituallas, Pulla, llamó), and the clear hand’s con- abbreviation turns up inside the cipher (contenté con el, con color de). About three quarters of the words are deciphered. Put together with the clear passages, the letter says this:

…no deve pasar … si no grande remuneración … por estar en tanto peligro el negocio, e a tanto lexos … [Venice holds] Brindizi y Otranto [in] Pulla … que sera bien que [they give us] puertos de Italia donde esta armada se pueda recoger quando el tiempo lo requiriese, por no aver de bolver tan lexos para … poner nuestros dolientes y heridos y ropa e vituallas, [and refit] estos navios … sin los ynconvenientes de estar en casas agenas. [When the Pope called me] para el cerco de … le demandé lo mismo por [the means of] Garcilaso, y lo ovo por bien … de buena voluntad; e por que los alcaydes eran españoles y criados del Rey nuestro Señor, yo me contenté … me parece deveys, Señor, fablar en esto con color de nuestro descanso y reparo. … segund su necesidad no creo que nada desto les sea ynposible … yo me desnudo y descargo y me satisfago en que [the business is] en las manos.

That is Gonzalo Fernández de Córdoba bargaining with Venice, through the Spanish ambassador there, before the joint campaign against the Turks at Cephalonia in the autumn of 1500: he will bring the fleet, but he wants Italian harbours of his own for it, as the Pope had given him. The full line-by-line transcription and decipherment are in f116_reading.md.

Two outside checks. Tomokiyo’s cryptiana page carries, commented out in its source, his own partial decipherment of the opening, “[paresce?] me que tan buena obra como esta con tanto diferencia e trabaio desto armada no deve pasar caso solo cargo sin grande [r]emuneración”, which corrects three groups first taken for misprints here: zap is zag = me, bac is vac = armada, and xie = cargo as printed. Sanuto’s Diarii (vol. III, cols. ~708–709) report the same demand from the Venetian side eight days later: the Spanish ambassador told the Venetian envoy in Rome that Gonsalvo wanted a cruciata, precedence, “qualli porto li piace a li bisogni” and victuals; off Corfù in October he told the Venetian proveditor he wanted a harbour “seperato” from theirs.

A third pass tested Sanuto’s terms (cruciata, jubileo, precedence) as cribs on recto lines 8–11. They are not there, since those lines weigh whether the enterprise suits Their Highnesses, but the second pass settled zie as parescer, the value Tomokiyo guessed: zie followed by the letters R I A and tener gives pareceria tener, and the same value fits all five places. Lines 8–11 now decipher as si empresa a propósito de sus altezas … no hablo en ello … segun la necesidad dellos ay … en semejante acatamiento pareceria tener mas respeto a ….

What is not deciphered. Five code groups still contradict Galende’s printed values wherever they stand: bog (three times, printed Rey de Portugal, probably boz = todo), and zeb, zems, xob, bue. Either the 1994 plates misprint them, as they visibly misprint others, or the letter used a variant copy of the table; the manuscript, BRAH 9/15 ff. 7–9, would settle it. About ten stretches of letter signs are also unplaced (grade I), mostly where the q-shaped N and the reversed-9 S cannot be told apart at this resolution. Words in the blockquote are grade C where the signs are certain and the Spanish runs, M where a word was completed from context.

04 No. 95: a key without a text

F. 122 is a single leaf of 31 dense lines, no address, no salutation, no clear word anywhere, dated 8 January 1497, three days before Federico’s letter at the other end of the volume. In May 2022 George Lasry sent Tomokiyo an “approximate” solution, and Tomokiyo published it: an image of the alphabet, one to three signs per letter, with a row of unassigned signs and a handful of code groups — bac bnh bon dah daf dae oht bed dal boo del. No plaintext has ever been printed.

Matching the symbols by eye against that image does not work: ÷ against ≐, the plain 7 against the 7 with a small o and the crossed 7, are distinctions a printed reconstruction makes crisply and a hurried 1497 hand does not. So the leaf was taken apart mechanically instead. Adaptive-threshold binarisation; connected components grouped into glyphs by horizontal overlap with diacritics attached, which gives 963 glyphs over 31 lines, a median of 31 to the line; Ward clustering of 28×28 normalised bitmaps; then the clusters, rather than the individual symbols, were labelled by eye from contact sheets against Lasry’s key.

The check that the labelling is right came before any decipherment, and it is the frequency profile. The clean clusters carry about two thirds of the 963 glyphs, so their shares of the whole leaf are all deflated by roughly a third; what matters is the order. Counted against every glyph on the page, e takes 9 %, a 7 %, o 5 % and n 5 %, then s, c, u, r, d, m, t and i, with q last at about 1 %. That is the Spanish ranking, e–a–o–n–s, obtained from a key reconstructed by someone else and a clustering that used no language information. The 1 % for q fits too, since q is rare but never absent in Spanish.

What comes out, checked line by line on 31 annotated strips, is Spanish about the French. The verified stretches: …emos franceses… (l. 4); bac que puedan merc[ed] … de Francia… (6); …dos cosas … a traer… (7); …con esto… (8); señoría … que esta … por (11); que me toca … mucho … sera … que bnh … haga (12); con esto … acorde … lo bueno… (13); …quedar … que … Francia… (15); …si a tratado … que gouernad … pero (16); …muy grandes cosas … no creo que… (17); …certaran … pues que se … esto … la parte aun (18); que se … encubren … que … quieren go- | -uernar (19–20, across the line break); por obra creo que … amigo (22); escreuir a… (23); dificultad … en los… (25). The nomenclator groups appear in clear letters in the middle of the sign runs: bac, bon twice, bnh four times, dal, and probably bed. bnh is the frequent one and is most likely a person or a place.

Two of Lasry’s assignments were corrected on the way: the sign shaped like an n with a cross-tail is m (Lasry: y); and his two 7-forms are confirmed as distinct: the plain 7 is d (it makes puedan) and the 7 with a small o is s (it makes franceses and escreuir). They can be told apart by cluster though not by eye, which is why the first transcription by eye had them reversed.

About a third of the symbols are still unresolved. The line-by-line decipherment is in the repository as f122r_reading.md, line by line, with … where the leaf is not deciphered. Three independent methods were tried: transcription by eye on the strips, the cluster-and-language-model hybrid, and a segmentation-free decoder that slides every template along the line and tiles it by dynamic programming. They agree on the same two thirds and fail on the same third, which puts the limit in the symbol shapes at Gallica’s 4,077-pixel scan rather than in the method.

05 Nos. 93 and 94: cipher family identified, key not available

These two are not deciphered. The catalogue’s phrase for them, “unidentified cipher”, can be narrowed. Both are written the way the office’s ciphers are written: single invented signs, interleaved with groups of two to four Latin letters. In no. 93 the groups are gto pie roe hug heg mat gnd gab zoe mae cpm lnq hoe hac zup qup gre zen gne; in no. 94 gag rah mnb mms nob gik luy mei nen mok pol pat par paq vaz mal nyb nyl gob gib lob moe nak rag lue. The standalone signs are + ÷ ʒ ff ıı :/ ⧻ 7.

The initial band of the code groups is the discriminator, because the nomenclator is one-part:

Both fall outside the two keys that are in print and inside the band of the third. There is one concrete lead: Bergenroth gives LUQ = capitán, and no. 93 has the group lnq; u and n are the same two minims in this hand. He also has muy = de, and muy occurs in no. 93. That is a lead only: his list and the CNI’s are both partial, and most of the groups in these two letters are in neither.

One alternative was tested and failed. If those groups were runs of letter-shaped symbols rather than code units (the Cifra general’s own alphabet looks like that, its i drawn as a 3, its o as a b, its n as a q), no key would be needed and an ordinary homophonic solver would recover the key from the leaf alone. Lines 1–21 of f. 118r were transcribed sign by sign, 1,016 tokens over 40 distinct signs, and annealed against a Spanish 5-gram model from eight starts. The best key scores −3.5 nats per token where real Spanish scores −1.8, and the output is not Spanish. The token statistics say why: 66 % of all p signs occur inside pie, 28 % of g inside gto, and the commonest trigrams (gto ×21, pie ×19, gnꝺ ×15, heg ×13) are far too concentrated for letter runs. The groups are atomic. Nos. 93 and 94 are nomenclator problems and need the key.

The work stops there. The Gran cifra survives only as Bergenroth’s nineteenth-century reconstruction in BNE MSS 20.211/52, and the Biblioteca Nacional returns a bot-check page on its viewer, its search and its image endpoints alike; the manuscript is absent from Europeana and Hispana; Bergenroth’s eleven volumes of Simancas transcripts on the Internet Archive are handwritten, and their OCR yields almost nothing (three hits for cifra across 3.3 MB of text). Arturo Quirantes has published two photographs of key sheets, but one is the first-campaign alphabet of 1494–98 (the same symbol repertoire with different values, as he warns), and the other is a partial list of the second. A second candidate is documented and unpublished: Galende Díaz’s file B.R.A.H. 9/15 opens with a Cifra del visorrey at ff. 1–6, which he describes and does not reproduce. No. 94 is a viceroy’s letter.

The dates, for whoever continues: no. 94 is Messina, 27 April 1503, the day before Cerignola. No. 93 is Venice, 24 February 1504, in the weeks after the Garigliano, when Naples had just been lost to Spain for good and Venice was deciding what to do about it.

06 Method, including what failed

Almost all of the work here was bibliographic, and the order mattered: shelfmark first, cipher second. Searching Espagnol 318 rather than “Spanish cipher 1497” found Parisi’s article, which closed no. 5 in an afternoon; searching for the cipher family found Galende Díaz’s appendix, which is the key to no. 92; searching for what Tomokiyo had done found Lasry’s key for no. 95: cryptiana says the letter “is solved” and publishes his alphabet as an image, but no plaintext. For three of the five an existing decipherment or key was found; no key was recovered here.

The machine side was a pipeline for turning a page of signs into a sequence of letters, built for no. 95 and reusable: seg.py (binarisation), glyphs.py (component grouping), cluster.py and montage.py (Ward clustering and contact sheets), assign95.py (the cluster-to-letter table), lm.py (a Spanish 5-gram model built on Don Quijote, normalised to the twenty-two letters of the period’s alphabet), and hybrid95.py (a decoder that searches for the best-scoring Spanish with the verified clusters held fixed). Line pitch comes from the autocorrelation of the ink profile: 113 px on f. 116r, 128 on f. 118r, 100 on f. 120r, 114 on f. 122r.

Three attempts on the unresolved third of no. 95 are recorded because they did not work.

• Clipping each glyph to its line band before segmenting, to stop descenders from the line above contaminating the boxes. It made things worse: the band cuts the tall signs in half, and nearest-neighbour matching of the mutilated shapes collapses onto d and n. The junk boxes are touching signs, not descenders.
• A segmentation-free decoder: slide every labelled template along the line by FFT correlation, tile the line left to right by dynamic programming with area-proportional scores and a penalty per column of skipped ink, then decode the tiles with the language model. With the tile count right it recovers the same lines as the transcription by eye and no more; 23 % of tiles have their top two letters within 0.05 of normalised correlation, and the language model, given that freedom, writes Don Quijote over them (don quiiote que el que).
• The letter-run hypothesis on no. 93, described in §05.

Scipy’s signal module is blocked by an application-control policy on the machine this ran on, so the correlations are done with numpy.fft directly; it is in the source in case anyone meets the same wall.

07 Sources

• BnF, Département des Manuscrits, Espagnol 318, ark btv1b52503046q on Gallica; notice cc349255 in Archives et manuscrits. The IIIF full/full images are 4,077–4,155 px wide and are the only ones that will do; Gallica returns HTTP 429 after about six of them in a row.
• Ivan Parisi, “Un cifrario in prestito per una lettera segretissima di Federico d’Aragona re di Napoli ai Re Cattolici nel BnF, Espagnol 318”, Studi di storia medioevale e di diplomatica, n.s. IV (2020), 157–177 — open access.
• Ivan Parisi, “La correspondencia cifrada entre el rey Fernando el Católico y el embajador Joan Escrivà de Romaní i Ram”, Pedralbes 24 (2004), 55–116; appendix II has the alphabet and nomenclator used in no. 5.
• Juan Carlos Galende Díaz, “La escritura cifrada durante el reinado de los Reyes Católicos y Carlos V”, Cuadernos de Estudios Medievales y Ciencias y Técnicas Historiográficas XVIII–XIX (1993–94), 159–178; appendix 1 is the Cifra general, pp. 167–173.
• S. Tomokiyo, “Spanish Ciphers during the Reign of Ferdinand and Isabella”, and his page of George Lasry’s decipherments, where the f. 122 alphabet is published as an image.
• Arturo Quirantes, “El CNI y el (no tan secreto) código del Gran Capitán” and “Descubierta un segundo código del Gran Capitán” (2018), with photographs of BNE MSS 20.211.
• Working files, images, key transcription and every script named above: targets/esp318/, with NOTES.md as the record of what was tried.

Catalogue entry 9 is updated accordingly: five items rather than four, no. 5 closed, no. 92 added and keyed, solvability raised because two of the five now have keys in hand.