972Unsolved Historical Ciphers
∧ 8 h c Ɛ ÷ ⊧ p ƀ h c ƀ Ɛ … ne domandamo [ƀ z Ʒ p ⊧ 8 ϕ d p ⊧] tocha ad nuy …
key not found: letter homophones, syllable signs, word signs

Sforza chancery → Giorgio del Maino · cipher of invented signs in clear Italian · 4 May 1446

Francesco Sforza’s chancery to Zorzo Maino, 4 May 1446

Francesco Sforza
fromFrancesco Sforza

Bibliothèque nationale de France, italien 1583 f. 68 (Archivio Sforzesco), DECODE R7898: a single slip, clear Lombard Italian with runs of invented signs between the clauses. DECODE gives no sender, recipient or date.

The slip was identified from Mazzatinti’s 1883 inventory, and a second cipher of the same day was found on a neighbouring DECODE record. Both were transcribed and run through a solver, and every Sforza key on DECODE was checked. The key was not found and the cipher was not deciphered. No earlier decipherment is known.

Daniel Bourdeau · posted · updated

Method: not solved · Extent: text not obtained

Summary. DECODE R7898 is one image of BnF italien 1583 f. 68, with no metadata. The slip is dated in clear “M°cccc°xlvj die iiij° may”, 4 May 1446. Giuseppe Mazzatinti’s inventory of the Sforza papers in Paris (Archivio storico lombardo X, 1883) describes it as “Risposta a quanto ha riferito Zorzo Maino (4 maggio). In cifre”: a reply, from Francesco Sforza’s side, to what his agent Giorgio del Maino had reported. The clear clauses are about not seeking or asking for something that “does not touch us”, and about seeking, “in the name of God”, what is due; the substance is in the cipher. The next leaf, f. 70, is another cipher of the same day, Vincenzo Amidani to Sforza from Milan, written in the same family of signs. It was found photographed on DECODE R7899. Both slips were transcribed (404 and 390 signs) and run through a homophonic solver (simulated annealing) with a Renaissance Italian language model: every run gave nonsense. Among the 208 Sforza key records on DECODE, an eighteenth-century copy of Angelo Simonetta’s cipher with “Vincentius” and others shows how these systems work. Each letter has several signs, there is a sign for every vowel–consonant pair, whole words have signs, and nulls are mixed in. Its signs are not the ones used here, and no key names Maino. Status: not solved. What would open it is the 1446 key for Maino or Amidani, or a colour scan good enough to transcribe every sign and diacritic exactly.

01 The document

The Paris volumes italien 1583–1593 are part of the Archivio Sforzesco that the Bibliothèque impériale bought in 1867. Mazzatinti’s entry for f. 68 sits under 1446 among letters to Sforza from Angelo Simonetta and Giovanni Stavoli in Venice, and from Foschino degli Attendolo in Cremona and Ancona. That spring Sforza was fighting in the Marche and bargaining with Filippo Maria Visconti, whose court at Milan Maino was reporting on. The slip carries an old number (21.), the folio 68, and the clear date line centred at the head.

The clear text, in Lombard spelling (nuy, havemo, refferemo), holds the frame of the reply:

… cetera. Che nuy no sapiamo [cipher] questi, ne cerchamo ne domandamo [cipher] tocha ad nuy cerchare questo, ma solamente cerchamo con lo nome de dio [cipher] nostra … [cipher] gli havemo rechiesto siano contenti fargli quello e dicto et ad quello se refferemo.

[cipher] voglia essere contento mettere per scripto [cipher] se tra loro no gli sera noma uno che no habia [cipher] debitamente lo debiamo havere [cipher].

The second paragraph asks someone to be content to put something in writing, and argues that if only one of them lacks it, “we ought rightly to have it”. Who and what are in the cipher.

A small slip with a clear date line and two paragraphs of invented cipher signs mixed with clear Italian
f. 68, the whole slip: the date M°cccc°xlvj die iiij° may at the head, a cipher line, then two paragraphs of cipher with the clear phrases (cetera Che nuy no sapiamo …, voglia essere contento mettere per scripto …) between the runs. The cipher is not deciphered. Image: Bibliothèque nationale de France, italien 1583 f. 68, via DECODE R7898.

02 The cipher

The cipher is written in invented signs: barred strokes, a barred b, a phi, a barred yogh, a long s, figure 8, a cross-circle and others, some with dots or hooks. Dotted separators (::, .:.) stand between runs, and three paragraphs open with the same three-sign group. With the diacritic variants merged, f. 68 has 404 signs of 26 kinds. Two signs are 12% each, two are 7%, and the rest trail off. Several long runs repeat: an eight-sign group twice, another eight-sign group twice, a four-sign group four times. The cross-circle stands directly before clear clauses several times. In the related key described below it is the word sign for de.

F. 70, Amidani’s letter of the same day, is all cipher: 390 signs of 31 kinds in another hand. It uses the same stock of signs, the phi, the barred b, the barred stroke and the cross-circle among them, but in different proportions. It is not certain that each sign means the same in both hands.

03 What was tried

04 What would finish it

A system of this kind, 800 signs split across two hands and transcribed from a binarized scan, cannot be broken from the ciphertext alone. Three things would change that. First, the key itself: the 1597 cartella should be searched at full size, and the fifteenth-century keys in Lydia Cerioni’s La diplomazia sforzesca nella seconda metà del Quattrocento e i suoi cifrari segreti (1970) should be checked. Second, a colour scan of italien 1583 ff. 68–70 from the BnF, so that every sign and diacritic can be transcribed exactly. Third, the seventeen other 1446 cipher letters from the same volume on DECODE (R7899–R7915), several from correspondents named on key 14. A decipherment of any of them in that key would show how far the family runs.

05 Sources

Transcriptions, solver scripts and notes are in the repository folder targets/it1583/.