French Ciphers during the Reign of Louis XIII

French ciphers during the reign (1610-1643) of Louis XIII are described. While only a small collection of specimens are presented, it is believed that they are representative of the French ciphers at the time.

Observations on Ciphers during the Reign of Louis XIII

Regent Marie de Medici

Ambassadors in Germany, the Low Countries, and Switzlerland

Ambassadors in Constantinople

Ambassador in Turin

Council of Béarn


Cardinal Richelieu


Observations on Ciphers during the Reign of Louis XIII

Two-Part Code Not Yet Established

Louis XIII's reign saw the appearance of a skilled codebreaker, Antoine Rossignol (1600-1682), who was recruited by Richelieu in 1628 and quickly established himself at the court. As for code making, two-part code is said to have been introduced by him. David Kahn, who examined several nomenclators at the time, considers this "most important technical improvement that nomenclators underwent in their 400-year reign" was introduced "about the middle of Rossignol's stewardship" (Kahn (1967) p.160-161). Although there had been two-part codes consisting of tables "per scrivere" and "per cavare" at least as early as 1588 (see another article), most ciphers continued with a nomenclature of alphabetically ordered elements.

Among the few specimens I know, Louvois' code (1676) is the first mainstream French two-part code (though one-part codes continued in use in other ministries) (see another article).

Code Elements with Figures with Diacritics

Unlike the entirely numerical ciphers after 1676, the earlier specimens I know from the personal reign of Louis XIV (1661, 1675, 1676) all employ two-digit figures with diacritics in the nomenclature (another article). I pointed out in 2019 that this characteristic was already seen in Henry IV's time (another article). Many of the specimens of ciphers in the time of Louis XIII presented herein also follow this pattern.

The cipher of Hesperien (a councillor of the Council of Bearn) uses three-digit figures rather than diacritics to expand the vocabulary of the nomenclature.

Change/Sharing of Ciphers

• The cipher (1612) of Sainte-Catherine, resident in the Palatinate from 1612 to 1620, was based on a cipher (1589) for Guillaume Ancel, resident to the Emperor from 1589 to 1603.

• Ambassador Sancy started to use a new cipher (called Sancy's Cipher-2 herein) soon after Louis XIII officially came of age on his thirteenth birthday in 1614, though Queen Mother's rule continued until 1617.

• Ambassador Césy at first used a cipher given to an extraordinary envoy sent before him (called Nans-Angusse Cipher herein).

• The Cesy-Coeuvres Cipher was used by d'Estrees (Coeuvres), Cardinal de Sourdis, and Sillery in Rome in 1620-1623 in writing to Cesy, Ambassador in Constantinople. Sillery (and Bethune) used another cipher (Cesy-Sillery Cipher) in writing to Cesy in 1624.

Regent Marie de Medici

When Henry IV was assassinated in May 1610, Queen Marie de Medici became regent for eight-year-old Louis XIII. Marie's letters of 15 September and 10 November 1610 to Mr. de Breves (undersigned "Brulart") in BnF fr.3789 (Gallica), f.17, f.19, contain short passages in cipher, not deciphered. The cipher does not seem to match the known ciphers used by Savary de Breves (see another article).

Ambassadors in Germany, the Low Countries, and Switzlerland

Jeannin de Castille, Guillaume Ancel, and Etienne de Sainte-Catherine

According to catalogue information, BnF Clair 362 (not available online) contains ciphers of P. Jeannin de Castille, sieur de Blancbuisson (ambassador in Switzerland) (November 1611), Guillaume Ancel, sieur de Montchesne et de Meulles (ambassador in Germany), and Etienne de Sainte-Catherine (ambassador in Germany) (1612), and BnF Clair 370 (not available online) contains diplomatic ciphers of Etienne Saint-Catherine.

According to Desenclos (2017) (citing BnF Clair 362, f.204-205), the cipher (1612) of Sainte-Catherine, resident in the Palatinate from 1612 to 1620, was based on a cipher (1589) for Guillaume Ancel, resident to the Emperor from 1589 to 1603. A specimen of Sainte-Catherine's cipher letter is given in Fig.3 (taken from BnF fr.15927, f.23).

De Baugy's Cipher (1616)

BnF Clair 369 (Gallica) contains cipher letters (1616) of Nicolas de Baugy, representative to the Emperor (Wikipedia) to Claude Mangot, Secretary of State for War and for Foreign Affairs (Wikipedia) (f.2 (undeciphered), f.59 (undeciphered), f.109, f.156, f.209, f.275, f.309). The cipher can be reconstructed as follows.

One merit of this cipher is use of figures with an umlaut for both letters and syllables, unlike De Castille's Cipher below, in which figures with an umlaut is limited to syllables.

De Castille's Cipher (1616)

BnF Clair 369 (Gallica) contains cipher letters (1616) of Pierre-Jeannin de Castille (Wikipedia), ambassador in Switzerland (f.11, f.13). The cipher can be reconstructed as follows. (The original cipher may be found in BnF Clair 362 (which I have not seen) mentioned above.)

This is more or less like a Caesar cipher, enciphering c as a, d as b, e as c, etc., with viariant forms all representing the same letter.

Du Maurier's Cipher (1616)

BnF Clair 369 (Gallica) contains cipher letters (1616) of Benjamin Aubery Du Maurier (Wikipedia), ambassador in the Low Countries, to Mangot (f.229, f.294). The cipher can be reconstructed as follows.

Du Maurier (or his clerk) intentionally left part of a word in the clear: "9 80, 5 est 47 31 26" reads "p ro t est a n s"; "14 31 38, 64, eu 7" reads "i n ge ni eu r", and "fort 34 34, 46 27" reads "fort i fi e r". Obviously, the clear text "est" (is), "eu" (had), "fort" (strongly) are meant to mislead would-be codebreakers.

Ambassadors in Constantinople

Sancy's Cipher-1

Achille de Harlay de Sancy (Wikipedia) succeeded Salignac as ambassador in Constantinople from 1611 to 1619. (Emanuel Constantin Antoche, "Un ambassadeur francais a la Porte Ottomane: Achille de Harlay, baron de Sancy et de la Mole (1611-1619)" (

BnF fr.16145 (Gallica) contains his letters from Pera (a district in Constantinople (Wikipedia), where there was a European community) in cipher to Villeroy or Puisieux (f.90, f.92, f.96, f.100, f.102, f.104, f.108, f.114) from August 1611 to June 1612. The same cipher is also used in letters to Puisieux or Queen Regent in BnF fr.16146 (f.374, 450, 452, 455, 460) (1611, 1614) and BnF fr.16147 (Gallica) (f.1-495 (except for f.46, 454), f.601 and f.609-619) (1611-1614) (the date on f.493v, f.602v, etc. may look "1615"; if so, this cipher was used even after the new cipher (below) came into use).

The original cipher is found in BnF fr.16146 (Gallica), f.414.

The nomenclature uses letters and Arabic figures with diacritics. For example, "a" with an overbar is "le roy", "o" with an overbar is "le grand seigneur" (i.e., the sultan). An "et" symbol (like a "mirrored 9") with an overbar is "M de Salignac." Other elements I encountered include: (with an overbar) 13 (ambassadeur), 23 (au), 24 (avec), 29 (autre), 46 (beaucoup), 58 (con), 59 (ce), 65 (capitulation), 67 (de), 68 (du), 69 (dit), 70 (don), 80 (en), 81 (ent), 82 (est), 83 (estre), 91 (france), 94 (faire); (with no marks) 15 (flamise?), 28 (holandois), 35 (jour), 37 (je), 38 (jay), 39 (jusque), 41 (la), 42 (le), 43 (luy), 44 (leur), 57 (me), 58 (mon), 77 (ou), 78 (ont), 79 (prince), 80 (paix), 81 (pays), 83 (porte), 84 (port), 85 (par), 86 (pro), 87 (pour), 88 (per), 89 (pra), 91 (que), 92 (qui); (with an umlaut) 5 (rien), 6 (re), 15 (sur), 30 (veoir), 31 (vaisseaux), 88 (pre).

This provides for several special signs: "ce qui sera entre ces deux caracteres ... sera nul" (cancel characters inbetween); "ces caracters ... doubleront leur prochain precedant" (double the preceding letter); "Et ceulx cy ... les anulleront" (cancel the preceding character).

Sancy's Cipher-2

Soon after Louis XIII officially came of age on his thirteenth birthday, 27 September 1614, Sancy started to use a different cipher in letters to the King or Puisieux in BnF fr.16145 (f.132, 134, 136) (1616); BnF fr.16147 (f.446, 454 (1618), f.499-606 except for f.601 (1615), f.623 (to the King, November 1614), and f.624 (to Puisieux, December 1614)). Use of the same cipher is also found in BnF fr.16148 (Gallica) (many from 1615-1618) and BnF fr.16149 (Gallica) (f.4, 13, 46) (1619). Sancy's letters in cipher are also found in BnF Clair 368 (1616), which I have not seen.

As with the previous cipher, this provides for signs to double the preceding letter, cancel the preceding character, and cancel characters inbetween. In one example, the doubling sign is used to repeat the preceding "de" in "au contrere de destourner ...." (BnF fr.16147 f.77)

BnF fr.16148 includes some undeciphered ciphertexts in this second cipher of Sancy. At least some are copies of deciphered ciphertexts in the same volume, but some seem to lack deciphered counterparts. For example, f.183 seems to correspond to the deciphered ciphertext at f.189 (but they are differently enciphered: see a symbol for "p" on the first line); f.194 is deciphered on f.187; f.248 is deciphered on f.246; but I have not located a deciphered copies for f.200, f.206.

Sancy was implicated when Samuel Korecki (Wikipedia) escaped shortly after the death (22 November 1617) of sultan Ahmed I (Wikipedia) because he had been sympathetic to the Polish prisoner. Sancy was held prisoner with his main servants. Louis XIII under the tutelage of his advisers sent Angusse, former secretary, and chevalier de Nans to Constantinople to demand full reparation. The French and the Ottomans were reconciled and Sancy returned to France in 1619 (Antoche p.758-759).

Nans-Angusse Cipher

Etienne de Nans and secretary Jacques Angusse, sent to Constantinople in May 1618 (BnF Ms.4770), used the following cipher in their letters to Puisieux in BnF fr.16148 (f.463, 466, 468) in December 1618 and in BnF fr.16149 (f.16, 26, 39, 43, 48, 51, 54, 59, 66, 69, 71, 73, 79, 81, 94, 98, 100, 102, 109) in 1619. (Since "qq"-like symbols stand out in the ciphertexts, I provisionally called it the "qq cipher.")

This cipher was also used in the first letters of the new ambassador, Cesy in December 1619 - January 1620 (BnF fr.16149, f.113, 119, 123).


Philippe de Harlay, comte de Césy, succeeded Sancy as ambassador in Constantinople from 1619 to 1641.

His letters in cipher are in BnF fr.16149 (Gallica, Gallica) (f.127-471) (1620-1623) and BnF fr.16145 (Gallica) (from f.140) (1622-1623).

The nomenclature elements I encountered include: (with an overbar) 23(le grand seigneur), 24(le premier visir), 25(Moufre?), 29(roy de perse), 31(l'empereur), 39(ambassadeur), 47(affaires), 48(au), 49(avec), 50(autre?), 51(bassa), 57(Constantinople), 60(car), 66(de), 67(dict), 68(dont), 74(entreprise?), 80(faire), 84(faict), 87(galere), 88(gallious), 90(gens), 95(holande), 97(homme), 98(hommes); (with a comma [virgule]) 12(intention), 17(luy), 18(la), 19(le), 20(leur), 21(lettres), 22(monsieur), 27(mort), 29(mais), 30(me), 32(nous), 35(ne), 40(ou), 41(ont), 44(pologne), 47(pour), 49(pre), 50(per), 51(par), 52(prince), 54(que), 55(quoy), 56(qui), 60(rien), 62(re), 66(sans), 69(traicte), 70(tenir), 71(toute), 72(tousjours), 74(tion), 80(venir).

Cesy-Coeuvres Cipher

The following cipher was used by François-Annibal d'Estrees, later Marquis de Coeuvres (Wikipedia), ambassador in Rome, in his letters to Cesy in 1620 (BnF fr.16151 (Gallica), f.15, 17, 20, 27). It was also used by François d'Escoubleau, Cardinal de Sourdis (Wikipedia) in Rome (f.45, 22 January 1622) and the chevalier de Sillery (see the next section) in Rome (f.51, 6 August 1623) in their letters to Cesy.

This employs several code names: something like "lensogire" for "roy", "la Trouipette" for "le grand seigneur", "la lanar" for "le pape".

Cesy-Sillery Cipher

Noel Brulart, chevalier de Sillery (Wikipedia) switched to the following cipher in his letter to Cesy of 20 January 1624 (BnF fr.16151, f.57). It was also used by Philippe de Bethune (Wikipedia) in Rome to Cesy in 1624 (f.64, 78, 81, 83, 86).

Ambassador in Turin


Claudio Marini, Marquis of Borgofranco, was ambassador in Turin in 1617-1629 (Gellard). A letter to him partially in cipher, dated 13 July 1624, is presented in Fig.3 of Anna Cantaluppi (2010-2011), "Le carte del genovese Claudio Marini, ambasciatore del Re di Francia in Piemonte, nell'archivio della Compagnia di San Paolo", Bollettino della Società Piemontese di Archeologia e Belle Arti (, which allows reconstruction of the cipher.

The substitution cipher uses mainly symbols rather than Arabic figures, but the nomenclature consists of two-digit figures and ones with an overbar. (His cipher in 1610 is in another article).

Council of Béarn

Hesperien's Cipher

BnF Clair 373 (Gallica) contains two cipher letters (1612) of Theophile Hesperien, a councillor of the Council of Bearn, to Paul Phélypeaux, lord of Pontchartrain and Secretary of State for Protestant Affairs (Wikipedia) (f.172, f.194). (Bearn, under personal union with France, was a separate principality (Wikipedia).) The cipher can be reconstructed as follows.

Use of three-digit figures rather than diacritics to expand the vocabulary of the nomenclature anticipates later codes. (The nomenclature includes 31((le) roy), 33(Mr le prince), 43[il], 44(Mr de la Foret), 53(Villeroy), 54(Hesperien), 58(avec), 61(ce), 62(con), 63(de), 64(du), 66(en), 67(est), 71(il), 73(la), 74(le), 75(les), 76(luy), 85(ne), 88(par), 90(pour), 91(que), 94(re), 96(si?), 98(tant), 99(vous), 111(...religion?), 113(ministres), 114(assemble...), 115(parlement?), 120(armes).)


BnF Clair 373 (Gallica) contains a cipher letter (unsigned, undated) to Paul Phélypeaux (f.303). The cipher can be reconstructed as follows.


Anonymous 2

BnF Clair 372 (Gallica), f.169, contains an unsigned cipher letter (June 1617). The cipher can be reconstructed as follows.

Cocquet's Cipher (1616)

BnF Clair 369 (Gallica) contains a partially enciphered letter dated Rome, 13? November 1616 from Cocquet to Mangot (f.316). It is not deciphered.

Unsolved Cipher of Fra Guglielmo Vizani

BnF fr.16158, f.292, is a letter of fra Guglielmo Vizani, 8 October 1637, in which some portions seem to be in an unsolved cipher.

Cardinal Richelieu

Cardinal Richelieu was Louis XIII's chief minister from 1624 until his death in 1642. He recruited Antoine Rossignol, who deciphered Huguenots' messages at the siege of La Rochelle in 1628.

Richelieu is said to have used the Cardan grill in both private and diplomatic correspondence (Wikipedia).

A specific cipher used in his correspondence in 1641 was identified in 2020, when Norbert Biermann solved a cipher letter dated Paris, 5 November 1642 and addressed to M. d'Aiguebère (Klausis Krypto Kolumne).

The letter is presented at an auction site, which describes some background.

D'Aiguebère was then in command of Aire (now a commune in the Pas-de-Calais department in the northern France), which the French army under La Meilleraye captured from the Spaniards in July 1641 (border towns between France and the Spanish Netherlands were the focus of contest in this theatre of the Thirty Years' War). Aire was in turn sieged by the Spaniards. La Meilleraye could not relieve, and in December 1641, deprived of food, the French army left the town (Memoires de Montglat in Collection complete des memoires relatifs a l'histoire de France, vol.49, p.315, 327, 329 (Google)).

The cipher can be reconstructed from Norbert's solution of the ciphertext.

Basically, it is a homophonic substitution cipher that has numbers, letters, and other symbols to represent the letters of the alphabet. Unlike dispatches in the ciphers presented above, only a few code elements are used. According to Norbert's conjecture, "39" is "secourir" and "44 is soldats". There are also unidentified "45" and "50". A "Delta-like symbol" is conjectured to be "Le Roy."


Camille Desenclos, "Transposer pour mieux transporter, Pratiques du chiffre dans les correspondances diplomatiques du premier xviie siècle", in Matière à écrire (2017)

See also my related articles:

S.Tomokiyo, French ciphers during the Reign of Henry IV of France

S.Tomokiyo, French Ciphers at the time of the Fronde

S.Tomokiyo, Ciphers Early in the Reign of Louis XIV

S.Tomokiyo, French Ciphers during the Reign of Louis XIV

©2020 S.Tomokiyo
First posted on 24 July 2020. Last modified on 18 October 2020.
Articles on Historical Cryptography
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