French Ciphers during the reign of Louis XIV are outlined in another article. The present article describes ciphers earlier in the reign.
Most of these ciphers use a homophonic substitution table plus Arabic figures with diacritics for syllables and some words.
French Diplomatic Ciphers from 1643-1649
Ciphers in Correspondence of D'Estrades (1647-1653)
Gaston, Duke of Orleans' Cipher (1644)
Correspondence Intercepted in England (1653)
Ciphers for Military Correspondence in BnF NAF 1045
Le Tellier-Colbert Ciphers (1650)
Colbert de Croissy and Purely Numerical Ciphers
French Diplomatic Cipher from 1661
French Diplomatic Cipher from 1675
French Diplomatic Cipher from 1676
Numerical Ciphers with Diacritics Early in the Reign of Loius XIV
Lord Digby's papers captured in October 1645 in Add MS 72438 include two French ciphers.
F.74-75 (DECODE R8697) is a cipher of M. de Boisivon. Probably this is the diplomat sent to Scotland at the request of Charles I in 1643 by the Duke of Orleans, brother of Queen Henrietta-Maria, rather than by the French court (Allan I. MACINNES, "Covenanting Exchanges with the French Court during the Wars for the Three Kingdoms" (doi)). The place names in the nomenclature (Londres, Paris, Bristol, Rouen, Exetre, Edinbourgh, Barwick, carlile, Oxford, Hull, Yorke, Newcaslte) seem to support the association of this cipher with the mission to Scotland.
At first glance, this is similar to French diplomatic ciphers at the time in employing Arabic figures with diacritics for syllables and words in the nomenclature. However, use of Arabic figures (rather than graphic symbols) in the substitution alphabet was not yet so common (but is seen in the Duke of Orleans' cipher (1644) below.)
F.86-87 (DECODE R8719) is a cipher between "Prince Harcourt" and Lord Digby. The Prince of Harcourt (Prince d'Harcourt, Count of Harcourt) was received by the Parliament late in 1643 and was even allowed to visit the King in Oxford (e.g., British History Online). Boisivon's cipher above mentions "L. Conte d'Harcour" after "l. Duc D'Orleans".
The cipher uses Arabic figures with diacritics for syllables and words in the nomenclature. The substitution alphabet uses both graphic symbols and Arabic figures.
Comte d'Avaux and Abel Servien were among the French delegation for the negotiation of the Peace of Westphalia (Wikipedia). BnF Baluze 172 (Gallica) contains letters to D'Avaux and Servien from Mazarin or Count of Brienne, Secretary of State for Foreign Affairs (1644-1645) (f.145, f.153, f.231, f.269). The cipher can be reconstructed as follows.
BnF Clair 411 (Gallica) contains a letter partly in cipher, from Cheylieu (London, 1 July 1647) (f.1), mentioning "Ferfax" (Fairfax), one of the great enemies of the King of England. The cipher can be reconstructed as follows.
BnF Clair 421 (Gallica) contains four letters partly in cipher as follows.
This letter of Henri Brasset, a French resident in The Hague (The Cambridge Descartes Lexicon), to "Vostre Eminence" (Mazarin?) has undeciphered ciphertext.
In 2023, George Lasry solved this by using his new algorithm for solving syllable ciphers. The syllable assignment to numbers (with a prime, an overbar, or an umlaut) has some irregularity. Apart from CV-syllables, other syllables and common words appear to be assigned in the range 21-40 (with no diacritics, a prime, an overbar, or an umlaut). 91 with an overbar deletes the preceding symbol. (Two lines (f.160v, f.161) are repeated in the letter, which indicates this may be an inaccurate copy.)
Here is pdf with images annotated with interlined deciphering (which I slightly adapted according to my interpretation).
Soon after I posted the above, George found the plaintext in BnF fr.17901, f.230 (Gallica, his transcription). By using the plaintext, he could derive the final key as follows.
The same cipher may be used in "Memoire chiffre de Henri Brasset (octobre 1648)" in BnF Clair 417 (not found online). A cipher received by Mr Brasvet in November 1650 is known (another article), but it does not appear to match.
BnF Clair 574 (1645 or 1649) (not found online) contains a cipher used by Brasset (f.3-4).
The cipher can be reconstructed as follows.
The cipher can be reconstructed as follows.
Graymond was a French agent in Edinburgh. The cipher can be reconstructed as follows. It seems to be the same as one broken by John Wallis (see another article).
Correspondence of Comte D'Estrades (Wikipedia) is preserved in BnF Clair. 577 and Clair. 579. In 1646, he was sent to Holland as ambassador extraordinary and he took part in the conferences leading to the Peace of Westphalia. During the Fronde, he continued to serve Mazarin.
In 2025, George Lasry kindly provided me with his analysis. He not only reconstructed most of the keys by using interlenear decipherment, but he even identified some keys by using his solver for syllabic ciphers.
The volume begins with two keys.
One is a numerical cipher (E=21/12/65), with a few codes in Italian ("Che 92 Per 93 Non 94 Puntofermo 91 Nulle dal no.70 sin' al 90") but with a nomenclature in French (Armée 10, ..., Passage 107).
The other consists of a substitution alphabet (E=2/23) which assigns one substitution letter and one figure to each letter of the alphabet and a nomenclature in French (DE=102) in two pages. This is annotated "chiffre pour l'Italie."
Inbetween is a note "chiffre avec M. le Duc de Modene" and (in a different hand) "Il pourroit estre de l'Ambassade de M. l'Abbe Estrad (?Wikipedia)"
Mazarin to [D'Estrades], Paris, 12 March 1647. The cipher is reconstructed as follows.
Mazarin to [D'Estrades], 26 March 1647. The cipher employed is the Mazarin-D'Estrades Cipher above (DE=¯38).
Prince Thomas de Savoie (Wikipedia) to [D'Estrades], 3 April 1647. The cipher is reconstructed as follows.
A letter in Italian. 4 April 1647 "in fiorenza". The cipher is reconstructed as follows.
Mazarin to [D'Estrades], Paris, 19 April 1647. The cipher employed is the Mazarin-D'Estrades Cipher (DE=¯38) above.
Somehow, the interlinear decipherment of this letter does not match the ciphertext. (So I didn't realize that this cipher was already reconstructed by George until after I independently reconstructed many syllables from correctly deciphered segments later in the letter.) The interlinear decipherment of the beginning part reads "je vais[?] envoyee une lettre de change de vint mille pistoles que je desire qui ne sait employees que par vos ordres et a ...," while the deciphered text reads something like "vous ne vous est[25']niez pas devoir arriver de de-la plus de troupes que vous ne jugez y [34'] subsister par ce qu'elles ny demeureront pas longtemps, faisant estat de le employer en quelque autre endroit sitost que le mois de may sera passe tant par ce que aussy bien ne pourroient-elles sy conservez a cause qui mauvaair[?] la saison ne permettra."
Prince Thomas de Savoie to [D'Estrades], 23 April 1647. The cipher employed is Thomas of Savoy's Cipher (DE=¯38) above.
A letter in Italian, Rome, 29 April 1647, annotated "si ualerà della Cifera di Mr. Brachet". The cipher is reconstructed as follows.
Mazarin to [D'Estrades], Paris, 30 April 1647. The cipher employed is the Mazarin-D'Estrades Cipher (DE=¯38) above.
Mzarin to [D'Estrades], Paris, 1 May 1647. The cipher employed is the Mazarin-D'Estrades Cipher (DE=¯38) above.
Cardinal Grimaldi(Wikipedia) to [D'estrades], Rome, 6 May 1647. In Italian. The cipher employed is Brachet's Cipher above.
Comte de Brienne(Wikipedia) to D'Estrades, 28 June 1647. The opening paragraph is in a cipher, reconstructed as follows.
Cardinal Grimaldi to D'Estrades, 2 July 1647. In French. A few phrases are in a cipher, reconstructed as follows.
This appears to be the same as Brienne's Cipher 1=Grimaldi's Cipher above, so I supplemented some reading with "?" in the table. But I have to say the deciphered text does not make much sense (with or without my supplements).
Cardinal Grimaldi to [D'Estrades], Venona[?], 4 July[?] 1647. In Italian. Almost entirely in cipher. The cipher, reconstructed above, is the same as Brienne's Cipher 1.
As it turned out, Grimaldi used a numerical cipher (Brachet's Cipher) in May 1647, but used a cipher with diacritics and syllables (Brienne's Cipher 1) on 4 July[?] 1647, before which he appears to have used the latter cipher (only substitution symbols, not syllables) for a few words in a letter in French.
A letter dated Piombin, 3 July 1647, attributed to D'Estrades in catalogue.
This undeciphered letter can be read with the Mazarin-D'Estrades Cipher above. The first cipher segment can be read "de ^55 [-] Si e u r [-] C he si e t de [Ba] r to lo me o Vi r gi li i qui est de re to u r a Ro me."
Marquis de Fontenai (Wikipedia), ambassador in Rome, to D'Estrades, Rome, 9 July 1647. The cipher employed is the Mazarin-D'Estrades Cipher above.
A letter in Italian addressed to "Illmo Sig.re Pr~on mio ossmo", 2 August 1647, in Italian.
A large part is in a numerical cipher with diacritics, of which only a few words in the beginning are deciphered. After the text, a cleartext is scribbled ("non hauende cifra con ...") but it does not seem to match the deciphered fragment. The key was reconstructed by George Lasry and Norbert Biermann.
Marquis de Fontenai 2 August 1647. The cipher employed is the Mazarin-D'Estrades Cipher above.
Brienne to D'Estrades, Paris, 19 September 1647.
This undeciphered letter can be read with Brienne's Cipher above.
Brienne uses a different cipher in 1651 (see below).
Comte de Brienne to D'Estrades, Paris, 28 April 1651.
Comte de Brienne to D'Estrades, Paris, 20 September 1651.
The cipher is reconstructed as follows.
A large part of the letter is in numerical cipher with interlinear decipherment. The cipher is reconstructed as follows.
At the beginning of the section "Année 1653" (f.339 ff.), there are small keys.
A sheet marked "341-343" is a substitution table (E=λ/30, DE=~36) with syllables (e.g., ba=25 with an overbar) and a small nomenclature.
P.345 lists some numerical codes, possibly an addenda to some other cipher (not the one above, because 25 with an overbar is "entre").
BnF Baluze 343 (Gallica) contains an original cipher endorsed "Chiffre pour bailler (Wiktionary) a Monseigneur Le Duc D'Orleans / Du x.e May 1644 / a Paris / Pour M. Goulas (?Wikipedia)."
The nomenclature employs letters with an overbar as well as Arabic figures, those with an overbar, and those with a double overbar. For example, Mazarin is represented by "s with an overbar." Arabic figures 8-35 with a circumflex are nulls. (Use of letters with an overbar for names is a feature also seen in Le Tellier-Colbert Cipher 1 (see below), Sancy's Cipher-2 (see another article), no.5 of the Nevers Collection (see another article).)
The list includes "La Royne d'angleterre" (42) as well as "Le Roy d'Angleterre" (41). As of 1644, the Queen of England was Catherine Parr (the sixth and last one of the six wives of Henry VIII). The entry may have been inherited from ciphers from an earlier period when divorcing and remarrying of Henry VIII were diplomatic issues.
BL Add MS 4200 appears to be letters intercepted by the English intelligence system led by John Thurloe, the Protectorate England's spymaster.
Add MS 4200, f.88 is a letter (30 May 1653 NS) from Antoine de Bordeaux, seigneur de Neuville, French ambassador in England (The Diary of Samnuel Pepys). I don't know whether this undeciphered ciphertext corresponds to known plaintexts (Some of his letters are calendared in Thurlow State Papers such as the ones from 10 April 1653 NS (British History Online) and from 8 September 1553 NS (British History Online)).
The letter is in DECODE R8390 (R8393 is a duplicate of the beginning; R8391 is a duplicate of the ending; statistical analysis is in R8386, R8388, R8389). My provisional transcription is here. The cipher employs diacritics and would probably include symbols for syllables as with other French ciphers at the time.
BnF, Melanges de Colbert 11 (catalogue), ff.479-481, is a copy of a letter from Mazarin to Antoine de Bordeaux from 22 June 1654 (DECODE R9482). The cipher looks similar to the above. (Lettres du cardinal Mazarin records other letters from this date from Melanges de Colbert 51, but not this piece (p.572).)
This was solved by George Lasry in 2025.
Add MS 4200 also includes eleven letters (1654-1655) between the Prince of Condé and Barriere (Henri de Taillefer, sieur de Barrière (Pujo, Le Grand Conde)), his agent in England. Again, some letters from the same period between them are calendared in Thurlow State Papers (From the camp of Noeyelle, 6 October 1654 NS (British History Online)).
The cleartext in these letters includes portions in English and French. I believe the original was all written in French, but substantial text in clear in the intercepted messages was translated into English, while short fragments were kept in French.
The letters from 1655 appear to use the cipher in f.108 (DECODE R8405+8406), including the undated one in f.96 (R8394) but with a possible exception of the short ciphertext in f.101 (R8398). The letter from 1654 (f.98, R8395) appears to be in a different cipher (which does not use a hacek). Actually, records show that there was some accident about the cipher in October 1654, and a new cipher was prepared.
The key in f.108 (DECODE R8405+R8406) is as follows (I will upload a fuller transcription to DECODE).
This cipher is better than in other contemporary French ciphers in that single letters, syllables, other words and names, and nulls share diacritics. For example, single letters may be represented by figures with a circumflex (^) or an umlaut (¨) (or other symbols based on Roman letters), while some syllables and words are also represented with figures with a circumflex or an umlaut.
Condé rebelled against the French court under the young Louis XIV and, after defeated by Turenne in July 1652, had defected to the Spanish Netherlands to fight the French. (Spain did not make peace with France at the Peace of Westphalia in 1648.) It may be speculated that the Prince of Condé might have had his source of cipher other than the king's court.
The letters in the volume are as follows. Some words I could decipher are shown in " " (though many parts are still unclear to me, partly because of illegible entries in the scan of the key and partly because the diacritics of the cipher symbols of the copy are often unclear or incorrect).
By the way, at one time, Mazarin, who had allied with Cromwell in 1655, mentioned Barriere's cipher letter in his letter to the ambassador Bordeaux.
It appears Mazarin told the ambassador to induce Cromwell to force Barriere to decipher the letter (three-fold causative -- what a grammar!).
Barriere also had a cipher correpondence with the president of Brussels, Viole (which is the spelling in the nomenclature of the Conde-Barriere Cipher (1655) but is transcribed as Vicle in one instance).
BnF NAF 1045 (catalogue entry) is "Recueil de chiffres de correspondances militaires pendant la guerre de Trente Ans," and includes chiffres du marechal de Turenne, du colonel d’Erlach, du duc de Candale, etc. I inspected the first 20 folios out of 57.
Eleven symbols for names (le roy, la royne, Mr le cardal Maza:, M le prince, Mr de buillon, Mr de turenne, Madame de buillon, Madlle de buillon, La ville de paris, Rouen, Orleans). (Turenne's family held the dukedom of Buillon.) A note reads something like "On a affaire de tous ces noms propres augmentez les tant que vous pourrez tant de personnes que de villes et mot ...."
The correspondent's name is illegible to me. Ehm? Shutz?
Substitution alphabet assigning two symbols (one graphic sign and one Arabic figure) for each letter. A point over a symbol doubles it. Ordinary letters of the alphabet are nulls ("nulles"). A figure with a bar under it represents the number.
The correspondent's name is illegible to me. Ehm? Shutz?
Substitution alphabet assigning two symbols (one graphic sign and one Arabic figure) for each letter (including k), with a nomenclature assigning Arabic figures up to 112 to names/words such as Mazarin (64), Schütz (97), Turenne (107). The assignment of figures is not completely in ascending order.
Ordinary letters of the alphabet are nulls ("ne valent rien"). 0 with a dot above or below is also insignificant.
Copy of f.3, with some difference in arrangement (e.g., the location of "Argent 26"; the assignment is the same).
Copy of f.3. In the margin, there is a message "Monsieur, si vous ne voul[?] servér pas de ce chiffre dans vostre premiere despesche je vous supplie de me donner un mot dadvis de la reception."
Substitution alphabet assigning two Arabic figures to each letter of the alphabet.
Cancelling characters seems to be used in a peculiar way. It seems to cancell vowels before and after itself. When it occurs between a consonant and a vowel, the consonant serves as a null ("nulle").
Erlac seems to be Jean Louis d'Erlach (Wikipedia).
Substitution alphabet assigning two symbols to each letter of the alphabet (including k).
The nomenclature employs Arabic figures and diacritics to represent names, words, and syllables.
It also provides symbols to double the precident, symbols to cancel the precedent, symbols to cancel the text inbetween, and nulls.
Substitution alphabet assigning a graphic symbol and an Arabic figure for each letter (including k).
The nomenclature assigns figures 32-492 (with many gaps) to names and words: Son Eminence (69), Cardinal (71), Mr le Tellier (79), Vranguel/Vrangel [Wrangel] (83), hatzfeld (87), Gen: Gleen (88), Collonel Ehm (22), Gen. M. Rosen [Rose] (93), Gen. M. Schenbec/Schönbeck (96).
Ordinary letters of the alphabet are nulls. A bar over a symbol makes it a null. A bar under a figure means the number. 0 with a dot above it is valid, but 0 without a dot is a null.
A copy of f.9-10 (with differences in spelling).
A note (in German?) dated 21[?] September 1643. The endorsement looks like "Giferen Caracters."
Substitution alphabet assigning a graphic symbol and an Arabic figure for each letter (including k, st, ch, sch).
The nomenclature assigns figures 30-368 (with many gaps) to names and words: Mazarin (42), Turenne (49).
The note about special characters is in German.
The endorsement looks like "Giferen ...."
A copy of the substitution alphabet of f.9-10.
The endorsement looks like "Giferen."
A copy of f.9-10.
Substitution alphabet assigning a graphic symbol and an Arabic figure for each letter (including k, st, ch, sch).
The nomenclature assigns figures 29-364 (with many gaps) to names and words: Richelieu (52).
Seems to be some note on the precedent.
A copy of f.14.
Ciphers used in the correspondence between Michel Le Tellier, Secretary of War, and Jean-Baptiste Colbert are interesting for their variety including partially two-part code.
Colbert's uncle was married to Le Tellier's sister, and Colbert had once had a post in the war office before the age of 20 (Wikipedia). At least since 12 June 1650, Colbert, working under Mazarin, showed the Cardinal Le Tellier's memoires in cipher and wrote to Le Tellier on behalf of the Cardinal (Lettres, instructions, et memoires deColbert, vol.1, p.12, 14, 21, 24, 25, 28, 44, 51; 112; 42, 63 [the letter of 22 December], 180). Colbert used his secretary at least for some cases (Lettres de Colbert p.42, n.1; p.44, n.1). In later years, there was rivalry between the two families (Gary B. McCollim (2012), Louis XIV's Assault on Privilege: Nicolas Desmaretz and the Tax on Wealth (Google), p.9; A. J. Geant, "The Government of Louis XIV").
BnF Baluze 103 (Gallica) contains letters from Le Tellier, Secretary of War, to Pierre de Marca (Wikipedia), who was sent as a governor of Catalonia, then occupied by the French. Le Tellier's letters use the following cipher in April to October 1644 (f.50 (undeciphered), f.171, f.189, f.200, f.230 (deciphered on separate pages)).
This cipher is more like many ciphers during the previous reign (see another article) in not using syllable representations.
(Designated "1A" because I found this after "1" and "2".)
BnF Baluze 331 (Gallica) contains letters between Le Tellier and Colbert. F.38 is an unsigned letter possibly from Le Tellier dated Paris, 11 June 1650 (Colbert was then at Compiègne with Mazarin).
The arrangement is generally alphabetical, but some irregularity is introduced.
This reconstructed key allows reading (for the most part) an undeciphered letter in f.100 (the above reconstruction includes symbols identified from this specimen) (The ciphertext reads something like "[Colbert?] a die a [M. le cardinal? M. le Tellier?] que monsieur de Luynes son fil[s] qui est ... son traite avec r pour le gouvernement de [To]uraine luy avoit dit ... de quarante mil livres ... pour desarrerages de pentions que M. le Cardinal luy ... Monsieur de Luyn[e]s la pressoit daccompagner ce memoire dune lettre addressa[n?]te a M. le Cardinal ... mais quelle prioit... lettre de recomandation de M. le Cardinal ...."). (Catalogue information says it is addressed to Le Tellier, but the words "a M le Tellier" at the top may be a decipherment of the beginning, if the underline of the symbol is significant.)
BnF fr.6885 (Papiers d'état de Michel LE TELLIER (1640-1678) et ...) (Gallica) contains letters from Colbert to Le Tellier in 1650.
The cipher used in f.6-f.11 (Colbert to Le Tellier, Amboise, 2 November 1650) can be reconstructed as follows. (Mazarin was also at Amboise, and wrote to Le Tellier on the same day (Lettres du cardinal Mazarin, iii, p.914).)
The same cipher is used in Colbert to Le Tellier, Bourg, 17 September 1650 (BnF fr.6884, f.109 (printed in Lettres de Colbert, tome i, no.20)).
BnF fr.6885, f.141-f.144, f,138-f.140 (Reims, Colbert to Le Tellier, 22 December 1650) is Colbert's letter and "memoire de S.E." in the same cipher. The latter is almost wholly in cipher, while Colbert's letters only modestly use cipher. The same cipher is used in other letters of Colbert of 26 December 1650 (f.158-f.161) and 27 December 1650 (f.162-f.163).
The cipher can be reconstructed as follows. It should be remembered that in the actual specimen, diacritics are often omitted. (Mazarin was also at Reims, and wrote to Le Tellier on the same day. The letter, apparently dictated, refers to himself as S[on] Em[inence]. (Lettres du cardinal Mazarin, iii, p.961).)
This cipher was also used by Mazarin('s secretary) in 1651, when Mazarin went into exile in Germany because of the Fronde (BnF Baluze 332; see another article).
Mazarin's use of this cipher is also seen in his letter to Le Tellier, 3 December 1652, and one to Servien and Le Tellier, 8 December 1652 (BnF fr.6891, f.342, f.353), which will allow filling some blanks in the above reconstruction.
The cipher used in Colbert's letters to Le Tellier from January 1652 (BnF fr.6889, f.5-6, f.15, f.23 (printed in Lettres de Colbert, tome i, no.78, no.79, no.82)) can be reconstructed as follows.
There is an undeciphered letter from Le Tellier to Marquis de Castelnau, dated 12 May 1657. (I thank Alexandre Pillon for the information about this.)
The letter is accompanied by the King's instructions in clear for the troops under Castelnau, requiring the general to advance the troops in Flanders. If the instructions (maybe a copy for Le Tellier's own record) were actually sent in cipher, the ciphertext may simply summarise or supplement the attached instructions (the ciphertext follows a phrase in clear "le dessein de Sa Ma.te estant"). If the King's instructions were indeed sent in clear, Le Tellier's cipher may tell some hidden intention.
In 1657, France was still at war with Spain even after the Treaty of Westphalia in 1648. Castelnau (Wikipedia) was under Marshal Turenne in Flanders. In this year, the French objective was to take Dunkirk and Gravelines. After an unsuccessful attempt at Cambrai, Turenne captured Saint-Venant and Mardyck. The next year, Turenne made a victory at the Battle of the Dunes, in which Castelnau commanded the left wing.
My transcription is here. The frequent symbols are: ~28 (9x), 13 (6x), 20 (6x),23~(5x), 30~(5x), l (5x). It may be a bit too short for cryptanalysis, but if the cipher has the regularity as in Le Tellier-Colbert Cipher 2 (December 1650-1652) (DE=13/59~) above, there may be a chance.
Le Tellier-Colbert Cipher 2 is the first two-part code in mainstream French ciphers known to me (if one does not count the Le Tellier-Colbert Cipher 1A), though the arrangement is not completely random. (Sporadic examples of two-part code are seen in the sixteenth century (Duke of Nevers, Edward Stafford).) The next specimen is Louvois' code (1676), which employs a completely random arrangement. Considering that Louvois was son of Le Tellier, it is probable that he learned of two-part code from his father.
The three ciphers used between the same correspondents in the same year do not follow a simple pattern of refinement. The cipher "1" (November 1650) is simpler than "1A" (June 1650), and was replaced by "2" (December 1650), the most complex of the three. It is wondered what circumstances led to these changes. I suspect "1" is by Colbert, while "1A" and "2" are by Le Tellier, but I have not evidence to support this. It is often said that two-part code was invented by the codebreaker Rossignol. It is wondered whether Le Tellier learned of it from Rossignol or he devised it himself or learned of it from any other source.
At one time, Queen Mother was so impatient to receive the decipherment of Le Tellier's memoires from Colbert.
Colbert stressed to Mazarin importance of keeping secrecy by cipher. (At this time, Mazarin was in exile because of the secnod Fronde.)
Colbert gave the following caution to Charles Colbert (Colbert de Croissy since 1662).
Melanges de Colbert 101 (Gallica) contains some letters written in 1659 from Ensisheim (Wikipedia) by Colbert de Croissy (The handwriting in the margin (relatively clear on f.491) seems different from "Croissy" but the letter is addressed to "Monsieur mon frere"), who had been appointed Intendant of Alsace in 1658.
F.439 and f.449 (April 1659; about the Count of Harcourt (Wikipedia)) as well as f.495 (July 1659) use the cipher below. The undeciphered text on f.491 (April 1659) can be read with this key ("M. le Cardinal n'a point le gouvernement de l'Alsace..."). The same cipher is used in f.362, which mentions "Brisak" and may be related to a review of the garrison of Brisach in 1659 (f. 376, 405) (actually, I mainly used this in the reconstruction).
Another letter of the same correspondents from the same period that uses this cipher is found in Bnf Baluze 178, f.23.
A copy of a letter from Colbert de Croissy to Mazarin, dated Danzig, 9 May 1660 (BnF Baluze 178, f.73) employs the following cipher, called Croissy-Mazarin Cipher (1660) herein for convenience's sake. This letter, not deciphered, can be read with the key reconstructed from intelligence from Frankfurt and Nuremberg (f.93, f.98), apparently also addressed to Mazarin ("vostre eminence" on f.98) by Colbert de Croissy (The intelligence from Nuremberg is followed by Colbert de Croissy's letter from Nuremberg dated 10 March 1660).
(The intelligence from Frankfurt has some undeciphered symbols (f.94), which the key below renders "p-s-s-e-i", "te-m-m-s", "jo-e-e-r-li".)
(The regularity suggests 43 for "di" should have a trema over it, but many instances are consistently without such a diacritic.)
BnF Baluze 178 (Gallica) contains many letters of Colbert de Croissy to Jean-Baptiste Colbert or Mazarin during his mission to Rome in November 1660-March 1661 (f.79, f.84, f.88, f.106, f.114, f.121 (undeciphered copy at f.126), etc. etc.). (Colbert de Croissy was absent from Alsace on this mission about some restitutions to be made by the Papacy to the Duke of Parma and the Duke of Modena (Fédération des Sociétés d'Histoire et d'Archéologie d'Alsace).)
The cipher can be reconstructed as follows. The reconstructed key allows reading undecihpered pieces (f.130 ("la maladie du pape continue ...", f.135 ("Monsieur le Cardinal Antoine et l'ambassadeur eussent renouvele ..."), f.138 ("que pour luy il ne jugeoit pas ..."), f.162 ("Monsieur le 323 m'a aussi fait ..."), etc.).
Unlike most of the other French ciphers at the time, this is a purely numerical cipher, and does not use diacritics. Exclusive use of Arabic figures is also featured in Colbert-Croissy Cipher (1666) (DE=151) below, but this cipher (DE=91) is better in that syllable codes are not always consecutive and at least some of the unassigned figures are used as nulls.
It is noted that Colbert de Croissy used more traditional-style ciphers with graphic signs for the substitution alphabet in Ensisheim (DE=28) in 1659 and Danzig (DE=42~) in May 1660, but his letters from Italy are in this numerical cipher (starting from the one from Modena, 10 November 1660 (f.84), followed by many others from Rome).
I note other numerical ciphers used by French diplomats had also connection with Italy: Cipher of de Foix (1579-1584), Maisse's Cipher (1585) (see another article), cipher no.61 of the Nevers collection (1593), Maisse's Cipher (1595) (see another article). It is wondered whether Colbert de Croissy learned of numerical cipher in his trip to Italy.
As seen below, Colbert de Croissy still used a numerical cipher in Cleves in 1666, but during his London embassy, he used a cipher consisting of figures with diacritics.
Colbert de Croissy at Cleves used the following cipher in 1666.
Unlike most of the other ciphers at the time (and like Colbert-Croissy Cipher (1660-1661) (DE=91) above), it employs three-digit figures as high as 337 (and 450 for null). Moreover, the diacritics seem irrelevant.
The cipher is used in Melanges de Colbert 136 (Gallica) f.146 (mainly used in the above reconstruction; on the bottom line of the first page, a null is used to separate succession of "le" in "le lecteur"), f.205, f.209, f.279, f.311, f.356, and f.435 (February 1666). The above key allows reading undeciphered paragraphs in f.205 ("le sieur de Beverlin envoye des ...") (the preamble in the clear says "Cette lettre n'est que la coppie de celle que je vous ay escrit de neufe par la voye ordinaire celle cy par La Haye pour une plus grande precaution desorte que sy vous avez receu la dicte lettre du 9 il est inutil de deschiffrer cette coppie"); f.209 ("pendent son absance le ...") ("coppie de la lettre escrite a Monsieur de lyonne le 12^e fevrier"); and f.356. The same cipher is also used in Melanges de Colbert 137 (Gallica), f.219 (13 April 1666).
Colbert de Croissy was ambassador in London from 1668. This time, he used the following cipher.
This cipher is used in many letters in Melanges de Colbert 149 (Gallica), f.109, f.113 (copy of a letter to Lionne), f.166, f.250, f.402, f.456, f.579 (October-November 1668); Melanges de Colbert 158 (Gallica), f.359, f.388 (March 1672); Melanges de Colbert 159 (Gallica) f.203, f.244, f.282, f.305, f.320, f.340 (May 1672); Melanges de Colbert 160 (Gallica), p.188, p.396, p.477, p.509, p.565, p.728, p.766, p.727 (June 1672) (page numbers, not folios; sometimes, the recto side is given an even number); Melanges de Colbert 161 (Gallica), f.346, f.371, f.422 (September 1672); Melanges de Colbert 162 (Gallica), f.43, f.105 (October 1672); Melanges de Colbert 163 (Gallica) f.147, f.412, f.493 (January-March 1673); Melanges de Colbert 164 (Gallica), f.105, f.303, f.444 (copy of a letter to Seignelay), f.447 (duplicate of the previous?), f.545, f.627 (for Seignelay), f.629, f.667 (May-June 1673); Melanges de Colbert 165 (Gallica), f.180, f.277 (July 1673); Melanges de Colbert 165bis (Gallica) f.470, f.500, f.502, f.546, f.557, f.592, f.630, f.651, f.664, f.683, f.691, f.715; f.452, f.563, f.621, f.667, f.710 (copy of a letter to Seignelay) (September 1673); Melanges de Colbert 166 (Gallica) f.23, f.27 (copy of a letter to Seignelay), f.30, f.46, f.128, f.145, f.335 (October 1673); Melanges de Colbert 166bis (Gallica), f.380, f.403 (November 1673); Melanges de Colbert 167 (Gallica), f.119 (8 January 1674; about purchase of cannon); Melanges de Colbert 176bis (Gallica), f.646, f.650, f.657, f.669 (November-December 1672).
This cipher is also used in some short passages in a letter to the Duchess of Orleans (Melanges de Colbert 149, f.457 (placed after f.460 in pdf)).
An undeciphered letter of Mr l'Evesque de Beziers, dated Madrid, 13 August 1670, in Melanges de Colbert 155 (Gallica) can be read with this key ("afin que silent reprise ...").
Jean-Baptiste Colbert was chief minister of state from 1661 until his death in 1683. He was appointed Intendant of Finances in May 1661 and, after the abolishment of Superintendent of Finances held by Nicolas Fouquet, became the first Controller-General of Finances (1665-1683). He was also secretary of the Navy (1669-1683).
Melanges de Colbert in BnF preserves, inter alia, correspondence of Colbert, in which some letters addressed to him use ciphers. The following is what I found by examining volumes 101-176 (as far as can be found on the Web) (these volumes correspond to the second out of the four parts of the collection according to Catalogue des manuscrits de la collection des Mélanges de Colbert, T. I. Nos. 1-343 (Gallica), p.VIII). It is noted that all these instances are in one-part code, though Colbert once used two-part code with Le Tellier in 1650 (see Le Tellier-Colbert Cipher 2 above).
Colbert is known to have used cipher with Fouquet in November 1651 (Lettres de Colbert, p.165, n.1).
Melanges de Colbert 108 (Gallica), f.218, is a letter dated 23 April 1662 from[?] Commandeur de Neuchaise [Nuchèze], vice admiral (Wikipedia), signed "Floridor". It employs a simple substitution cipher. The undeciphered text on f.222, endorsed "pour monsieur Colbert", can be read with the reconstructed cipher below ("Scituation de l'isle d'Alboran. Alboran est une isle scituee ....").
The same cipher is used in Melanges de Colbert 109 (Gallica), f.556 (a partially enciphered copy of a memoire sent to "grand maistre" (Wikipedia), as revealed by decipherment) and f.559 (already deciphered).
Melanges de Colbert 120 (Gallica), f.285, is a letter dated 20 April 1664 from "M. de Fremont", ambassador in Portugal (Wikipedia). This looks like a simple cipher, but there remains a possibility that the reconstruction below is part of a full two-part code.
The next ambassador in Portugal (1664-1671) (Wikiwand), abbé de Saint-Romain, used a much complicated cipher in a letter in 1668 in Melanges de Colbert 149 (f.116 (undeciphered duplicate), f.126).
The same cipher is used in Melanges de Colbert 133 (Gallica), f.131, which is a letter of Comte de Schomberg (Wikipedia) to Colbert de Terron (Wikipedia) (see f.133v, which is before f.131 in pdf), dated 13 October 1665. Schomberg had been sent to Portugal as a military adviser.
This shows that a military commander and an ambassador shared a cipher in Portugal.
Melanges de Colbert 127 (Gallica), f.349, is a letter from Ratisbon, dated 29[?] January 1665, signed "Estrauelse"[?]. It has a few words in figure cipher, not deciphered. The cipher seems different from the one in the same volume below.
Melanges de Colbert 127bis (Gallica), f.1106, (Varsovie [Warsaw], 27 February 1665) and Melanges de Colbert 133 (Gallica), f.246 (Danzig, 11 November 1665) from Guillaume de Jeure Millet, minister sent to Poland, employ the following cipher. Many syllable assignments are the same as those of the Colbert-D'Estrades Cipher (1666) below.
Comte D'Estrades (Wikipedia) in The Hague used the following cipher in 1666. (During the second Anglo-Dutch War (1665-1667), France was an ally of the Dutch.)
The cipher is used in Melanges de Colbert 136 (Gallica), f.465 (25 February 1666); Melanges de Colbert 137 (Gallica), f.426 (22 April 1666); Melanges de Colbert 137bis (Gallica), f.847 (20 May 1666); Melanges de Colbert 140 (Gallica), f.265 (9 September 1666); Melanges de Colbert 142 (Gallica), f.373 (2 December 1666) (mainly used in the above reconstruction); Melanges de Colbert 142bis (Gallica), f.782 (16 December 1666).
Melanges de Colbert 144 (Gallica), f.483, is a letter from Denis de la Haye, sent to embassay in Constantinople, to Colbert, dated 30 July 1667. The cipher can be reconstructed as follows. (F.485v has "pour" in clear, which actually is a part of the word "pour-r-ois". This kind of deception seems common because I have seen it in other examples.)
The above key allows reading of the undeciphered text in Melanges de Colbert 134bis (Gallica), f.693, f.707 (De la Haye to the king (23 December 1665: "je juge qui'l estoit des..."; 25 December 1665: "le seul cle de plasir que j'ay de ...") and Melanges de Colbert 138 (Gallica), f.437, f.441 (11 June 1666: "il estoit a souhetter ..."; 27 May 1666: "me fist dire le ministre de la republique ...").
Melanges de Colbert 157bis (Gallica) contains letters in cipher (1671) from Simon Arnaud de Pomponne (f.476, f.513) and Nicolas Bautru de Vaubrun (f.822), both sent to Sweden to obtain an alliance to isolate Holland. The cipher can be reconstructed as follows. The substitution alphabet is almost identical with that of the Colbert-D'Estrades Cipher (1666) above.
A letter dated 23 April 1672 by the abbe Jacques de Gravel in Melanges de Colbert 159, f.102, employs the following cipher.
While figures with a prime accent constitute the nomenclature, use of diacritics (overline, underline) is not consistent for letters and syllables.
The comte d'Estrees (Wikipedia) used the following cipher in a memoire to the King in Melanges de Colbert 159, f.313 (25 May 1672). The same cipher is used in d'Estrees' letters and memoires in Melanges de Colbert 160 (Gallica), p.23, p.32, p.57 ("Coppie de la lettre de M. Colbert amb. a Londres"), p.200, p.270, p.298, p.420 (June 1672) (page numbers, not folios; sometimes, the recto side is given an even number) and Melanges de Colbert 165bis (Gallica), f.624.
Melanges de Colbert 165bis (Gallica), f.731, is a letter of Louis II de Bourbon, Prince of Condé, written at the camp near Audenarde [Oudenaarde]. The cipher can be reconstructed as follows.
This does not employ diacritics. Moreover, unlike other ciphers, both the letters of the alphabet and syllables and words are arranged in a single series.
Melanges de Colbert 171bis (Gallica), f.607, is a letter of the Duke of Chaulnes (Wikipedia) in Rennes in Brittany (June 1674). (Chaulnes was governor of Brittany (Wikipedia).) (The same cipher is also used in f.482, f.534, f.565 in a separate pdf.)
Melanges de Colbert 172 (Gallica), f.23, is a letter of Louis de Béthune, Duke of Charost (Wikipedia) (July 1673). The cipher is not deciphered. There is a number as high as 489.
Melanges de Colbert 168bis (Gallica), f.553, is a copy of a letter from the abbe de Gravel to Comte de Maulevrier, dated 16 August 1674. Short passages are in cipher, not deciphered. There is a number as high as 474 ("je l'ay pris au mot et luy ay propose de 433 168 75 232 284 415 75 481 141 481 79 141 112 474 141 287 327 99 481 415 199 de les bien ....").
A cipher from 1661 is described in Jörg Ulbert, "Zur Verschlüsselung französischer Ministerialkorrespondenzen" in Geheime Post (2015). It was for correspondence between Jacques-Auguste de Thou (BnF) and Cardinal Mazarin.
The cipher employs figures 1 to 99 as well as letters and various other symbols and has a total of 307 entries.
Use of diacritics allows the figures to be used in multiple meanings. For example, "44" represents "ha" but it means "bon" with an umlaut-like points, "nu" with a grave accent, "Mrs les Estats" (i.e., the States General of the Netherlands) with an overbar.
Simiarly, "q" represents "l" by itself but "barred q" means "k", "double-barred q" means "h", and "triple-barred q" is a null.
The cipher also provides for cancellation symbols. That is, the figures 100 to 106 with a horizontal line cancels the immediately preceding figures. Some symbols (e.g., 91, 95 by themselves and 92, 94, and 96 with a horizontal bar) double the preceding letter.
This cipher is similar to the cipher from 1676 of the next section in its use of figures with diacritics.
A small image of a French diplomatic cipher from March 1675 is available on a website for France-Bavaria cooperation.
The single letters, syllables (V+C and C+V), and some names are assigned two-digit figures. Unlike the cipher from 1661 above, there appear to be no symbols other than Arabic figures. Figures for syllables and names have diacritics.
(The image below shows only its skeleton of the cipher part. Figures, hardly legible in the small image, are omitted.)
This section describes a cipher in an intercepted letter of June 1676 from French ambassadors at Nimwegen to the King. At the time, France was engaged in the Dutch War (Wikipedia) but Louis XIV had sought peace after the campaign in 1674. Despite mutual distrust among the allies against the French, Nijmegen (Nimwegen) was accepted as the place for peace negotiations. But it was only at the end of 1676 that all the ambassadors arrived there (Baxter, William III, p.128-130) for negotiations for the Peace Treaty of Nijmegen (Wikipedia).
The deciphering of the letter is described in a contemporary treatise found in the archives in Brussels and printed in Devos et al. (1967) (p.72 ff.).
The cipher gathered from the treatise is as follows.
This employs Arabic figures with two accents to represent single letters (possibly monoalphabetic) and figures with a grave accent, a tilde, an overbar, an umlaut, or a circumflex to represent syllables or small words in generally alphabetical order. These figures are within the range 1-99 with one exception: 100 with an umlaut for "ter". Some three-digit figures are code numbers.
The striking weakness in this cipher is that figures with two accents are exclusively assigned to single letters. This provides a breach for codebreakers. The author of the treatise says the cipher proposed for the Secretary of State avoided this weak point by mixing ciphers for the same kind of referents among various columns (p.88-89). Among the Spanish ciphers in the 17th century transcribed in another work of Devos (see another article), use of the term "column" reminds one of the type of Spanish ciphers such as Cg.56 (1698) but the same precaution could have been attained by earlier Spanish ciphers via other schemes. It is yet to be found out whether the proposal of the author of the treatise was put into practice.
The above-mentioned treatise, titled "Traité de l'art de déchiffrer", in the Archives Générales du Royaume in Brussels is printed in:
Devos et al. (1967), L'art de deschifrer: traité de déchiffrement du XVIIe siècle de la Secrétairerie d'État et de Guerre Espagnole.
It is in French and was probably written by someone involved in Spanish deciphering activities in the Low Countries. In discussing regular/irregular assignment of syllables to code numbers, the author mentions deciphering of a letter sent to the Low Countries "two years ago" by the Secretary of State by the order of the Spanish King for experimenting in the art of deciphering (p.55).
The author of the treatise, who had the original of the above-mentioned letter of June 1676 in his possession, is not known and Devos gives a safe dating of the treatise as 1676-1714. The several references to the actual deciphering activities may help further study. P.48 mentions identifying an "X" led to deciphering of a letter from Louvois to Comte d'Estrade. According to page 53, a technique for identifying homophones was employed in deciphering in the Low Countries "four months ago" a letter from the minister of Sweden in Paris to the Count of Rybenach [Rübenach], in which "Meclenbourg" occurred frequently.
A letter used in demonstration of deciphering of a Spanish despatch is said to be a portion of a report of the "success of 14 August" and reads: "Donde los hechos hablan de por si es ocioso al discurso ponderarlos y teniendo el presente tantas circunstancias que solo la admiracion puede celebrarlos dignamente no se gastaran en su narracion mas palabras de las que bastaren a referirlas." (p.70) (This text appears to refer to no specific event. One event of this date is the Battle of Saint-Denis (Wikipedia) in 1678 but it may not be called a success.)
Use of diacritics with Arabic figures is common in the ciphers described above as well as some ciphers during the reign of Louis XIII (see another article) and another during the reign of Henry IV (see another article). It seems certain that use of Arabic figures with diacritics was characteristic of the French diplomatic ciphers at the time.
Arabic figures with diacritics are not seen among other French ciphers during the reign of Louis XIV described in another article, of which the earliest one, by Louvois, Minister of War, dates from 1676, the same year as the last of the ciphers presented above. Further specimens are wanted to discern whether Louvois' cipher of 1676 introduced the change in the French ciphers.
Still, a simplistic picture that Arabic figures with diacritics gave way to pure numerical ciphers in 1676 does not hold. The above shows that a pure numerical two-part code (albeit in not completely random order) was used as early as 1650 (as far as syllables/words are concerned) (Le Tellier-Colbert Cipher 2). Although Colbert's later correspondence does not show evidence of his use of such a strong code, some of his ciphers relies on three-digit figures rather than diacritics (Colbert-Croissy Cipher (1666) (DE=151)). Colbert-Conde Cipher [1673] (DE=91) is interesting in that figures representing letters are mixed with those representing syllables/words, though the arrangement is still alphabetical.
Lettres, instructions, et memoires de Colbert, vol.1 (cited as Lettres de Colbert herein) (Cour de France.fr)
Héder, M ; Megyesi, B. The DECODE Database of Historical Ciphers and Keys: Version 2. In: Dahlke, C; Megyesi, B (eds.) Proceedings of the 5th International Conference on Historical Cryptology HistoCrypt 2022. Linkoping, Sweden : LiU E-Press (2022) pp. 111-114. , 4 p. [pdf]
Megyesi Beáta, Esslinger Bernhard, Fornés Alicia, Kopal Nils, Láng Benedek, Lasry George, Leeuw Karl de, Pettersson Eva, Wacker Arno, Waldispühl Michelle. Decryption of historical manuscripts: the DECRYPT project. CRYPTOLOGIA 44 : 6 pp. 545-559. , 15 p. (2020) [link]
Megyesi, B., Blomqvist, N., and Pettersson, E. (2019) The DECODE Database: Collection of Historical Ciphers and Keys. In Proceedings of the 2nd International Conference on Historical Cryptology. HistoCrypt 2019, June 23-25, 2019, Mons, Belgium. NEALT Proceedings Series 37, Linköping Electronic Press. [pdf]
S.Tomokiyo, "French Ciphers during the Reign of Louis XIII"
S.Tomokiyo, "French Ciphers at the time of the Fronde"
S.Tomokiyo, "French Ciphers during the Reign of Louis XIV" (a sequel to the present article, addressing ciphers from 1676-1704)