Several French ciphers from the period 1550-1557 are reported in Jean Brunon et Jean Barruol, Les Français en Italie sou Henri II based on the papers of the baron de Fourquevaux (1508-1574).
Brunon et al. reproduces Henry II's letter to Fourquevaux dated 3 December 1553 (p.76). They could reconstruct the cipher from Fourquevaux's decipherment.
As with Spanish (see another article) and English (see another article) ciphers at the time, this employs non-alphanumeric symbols. For many letters of the alphabet, more than one symbol is assigned. (In the image above, variant forms in handwriting are also given for reference's sake.) Numerical symbols for representing double letters appear to be assigned regularly. Many symbols are provided for nulls. Frequently used words are given special symbols.
The British Archives have some ciphers of Henry II, deciphered by John Somer.
SP53/23 no.1 is a cipher between Henry II and Noailles (Wikipedia), ambassador in England.
Each letter of the alphabet is assigned two symbols (or three for "a", "e", and "s"). Common words are represented with two-digit figures (66 for "de", 40 for "que", etc.) or a symbol for "le". Four nulls are included. One letter written in this cipher is printed (in plaintext) in Sheila R. Richards (ed.), Secret Writing in the Public Records, p.17 (deciphered from SP 70/147/35-36).
SP53/23 no.3 is a cipher between Henry II and d'Oisel (Wikipedia), representative of France in Scotland.
Each letter of the alphabet is assigned up to five symbols. Common words are given special symbols or, in some cases, two-digit figures (50 for "plus", 80 for "pour", etc.). Some symbols and words are designated as nulls.
SP53/23 no.2 is a cipher between Noailles and d'Oisel.
Each letter of the alphabet is assigned up to four symbols. Double letters "rr", "ss", "ff" are given special symbols. "Roy de France" is represented by "Dedans." Three symbols and two numbers ("440", "446") are designated as nulls.
Etienne Bazeries' Les Chiffres Secrets Dévoilés includes a cipher of Sebastien de l'Aubespine (1518-1582) (Wikipedia), abbot of Bassefontaine and ambassador of France, used in his negotiations with the Landgrave and others in 1555. This looks similar to the King's cipher above (1553).
When Mirandola in Northern Italy was under siege, the Marshal de Thermes (Wikipedia), commander of the French relief, used cipher in writing to Fourquevaux, who guarded the place. Brunon et al. reproduces two of such letters: ones dated 12 October 1551 (p.41) and 9 November 1551 (p.48) and reconstructs the cipher.
The cipher is similar to the one used by Henry II above, though this cipher employs symbols rather than numerals for double letters. This cipher is also used by Cardinal of Ferrara (Wikipedia), Constable Montmorency (Wikipedia), M. de Lyle and de M. de Bonacorsy.
Aloys Meister, Die Geheimschrift Im Dienste der Papstlichen Kurie von Ihren Anfängen bis zum Ende des XVI. Jahrhunderts (1906) includes a very similar cipher between Thermes and "Jorquevaul" (p.225). If Brunon's reconstruction and Meister's transcription are both correct, they are not identical: a symbol like "oooo" is a null in Brunon et al. but represents "les" in Meister; the symbol for "les" in Brunon et al. is assigned to "lug" [luy?] in Meister; the symbol for "vous" in Brunon et al. is assigned to "nous" in Meister, etc.
Brunon et al. (p.81) includes a reproduction of a cipher between the Bishop of Lodève and Fourquevaux. Written on one sheet of paper, it is generally similar to the above ciphers. Each letter of the alphabet is assigned three symbols (or five for vowels). After A-Z, there are two extra symbols (maybe "et" and "con" or "que"; cf. Meister p.314, 214, 225, 229, 230, etc.). Double letters are given symbols (rather than numerals). 28 monosyllable words as well as about 50 names and words are given special symbols (numerals for some).
Brunon et al. (p.91) includes a reproduction of a cipher between Pierre Strozzi (Wikipedia) and Fourquevaux. This is much simpler than the ciphers above. It assigns each letter of the alphabet one symbol or numeral: "8" for A, a nabla-like symbol for B, "15" for C, "i" for D, "zz" for E, "60" for F, etc. Fifteen names ("Roy de france", "Reyne de france", etc.) are given special symbols.
A cipher for the Duke Marcantonio of Paliano (?Wikipedia) is in BnF Clair 351 in ff.173-176 in two copies.
A collection of Duke of Guise's cipehrs (1556) found in BnF fr.20974 are presented in another article.
BnF Colbert 391 (Gallica), f.43, contains a letter largely in cipher dated 15 February 1557 from François, Cardinal de Tournon[?] (Wikipedia), to Saint-Laurent, ambassador to the Swiss cantons. The cipher can be reconstructed as follows.
BnF Dupuy 44 (Gallica) has a ciphertext (f.39), which, according to the catalogue information, corresponds to a decipherment (f.40), a letter of Philibert Babou de la Bourdaisiere (c. 1484-1557) (Wikipedia) from his son, Philibert (made cardinal in 1561) (Wikipedia). (Philibert Babou de la Bourdaisiere deciphered intercepted foreign letters for Francis I (Vigenere (1586), Traité des chiffres f.34v; Kahn (1967), The Codebreakers, p.111).)
Although the ciphertext is accompanied by plaintext, I could not reconstruct the cipher. To me, the plaintext (containing about 3000 letters according to my very rough counting) seemed too long for the neatly written ciphertext (about 1000 letters). In 2022, Geoge Lasry broke the cipher (see another article). As it turned out, the ciphertext seems to be independent of the plaintext letter. It is interesting to see to whom the cipher letter belongs.
BnF Dupuy 44 (Gallica) (f.49-52; f.51 is a decipherment of f.51bis) is a letter from Odet de Selve (Wikipedia) to Henry II dated 21 August 1557. The cipher can be reconstructed as follows.
BnF Dupuy 265 (Gallica) contains several cipher texts, which Paul Friedmann used to reconstruct some ciphers (see another article). George Lasry noted there are some left undeciphered and solved them in 2022.
According to catalogue information, f.101 is a letter of Charles Marillac, ambassador in Germany, to cardinal Jean Du Bellay (Bishop of Bayonne), Augsburg, 18 November 1550.
F.228-238 is a letter from Montmorency to cardinal Du Bellay. (This may be the same as f.231 in Paul Friedmann's list.)
F.336 is a letter from Nicolas Raince, resident in Rome, to cardinal Du Bellay (not in Paul Friedmann's list).
BnF fr.3138 (Gallica), f.59, is a letter from Claude de la Guiche, Bishop of Mirepois, to Montmorency (Rome, 22 November 1551). This was found and solved by George Lasry in 2022 (see another article).
The volume contains more ciphertexts already deciphered:
(f.11 is not in cipher but Arabic. Sultan to Henry II (1556).)
f.21 (p.26-30 of pdf) 9 Lettre au roi, avec chiffre et dechiffrement, de F[RANCOIS], cardinal DE TOURNON,... De Fossembrun, ce XXVIIe de febvrier 1556.
f.32 (p.38-44) 13 Lettre avec chiffre et dechiffrement de PHILIBERT BABOU, e[veque] d'Angoulesme... au roy... De Romme, ce XIme jour de jung 1558
f.59 (p.65-68) 22 Lettre, avec chiffre, de CLAUDE DE LA GUICHE, e[veque] de Mirepois... a monseigneur le duc de Montmorency,... De Rome, ce XXIIe novembre 1551
f.66 (p.72-74) 24 Lettre, avec chiffre et dechiffrement, de DE MORVILLIERS,... au roy... De Venize, le XIIe jour de novembre 1549
S. Tomokiyo, "French Ciphers during the Reign of Francis I"
S. Tomokiyo, "French ciphers during the Reigns of Charles IX and Henry III"