A one part codebook from 1676 but topped with tags () ()

The Louis XIV's codebooks

Introduction (introduction)
The invention of the great chipher (invention)
Analyse of Louis XIV's codebooks (analyse)
Cryptanalyse (break)
Codebooks examples (examples)
- A codebook from 1643
- A one part codebook from 1676
- A two part codebook from 1676 (the first one?)
- A one part codebook from 1684
- Messages encoded by a two part codebook from 1685
- A two part codebook from 1688
- Messages from 1690, an unpublished codebook?
- The codebook from 1691 broken by Bazeries
- A codebook from 1701
The Man in the Iron Mask (mask)

An encrypted letter from June 1676

Here is an encrypted letter in French composed in the month of June 1676. It was carried by a courier from France who carried encrypted letters addressed to King Louis XIV and written by his ambassadors from Nijmegen. She was intercepted in the Netherlands. It was found in a report (probably very confidential) dealing with cryptanalysis and written by the Spanish cipher office of the time.

If we do a frequency analysis, the most frequent groups correspond (logically) to letters and syllables. Here are the most frequent groups (in descending order): s, t, a, n, le, ne, se, te, e, i, de, r, que, b, l, y, au, p.

Description of the code used

This code, unlike the previous code (from 1643) no longer contains special characters, but it is not composed of pure numerical groups. Indeed each group corresponds to a number but surmounted by a string of characters which associates it with a particular group (which was also the case in the code of 1643). Here are the strings that tag groups: « // », « - », « .. », «~ », « ^ », « \ ». Some number groups are not tagged.

Here is the reconstruction of the code:

The groups without tags
-----------------------
19 ???            32 et             193 Princes       378 ambassadeur
31 y              124 Nimegue
The groups surmounted by double slash (//)
------------------------------------------
02 a              13 l              24 d              56 p
04 c              14 n              32 m              61 y
06 e              16 p              38 s              62 y
10 i              18 r              40 u              64 et
12 b              20 t              44 s
The groups surmounted by a hyphen (-)
-------------------------------------
01 il             29 leur           46 mes            75 nest
11 interest       31 on             49 ment           83 on
16 en             36 ma             59 ne             89 oit
19 le             38 -              61 ni             94 tou
21 li             39 mes            65 ny             96 pa
25 la             41 mi             67 nous           99 pe
26 les            43 moy
The groups surmounted by a umlaut (..)
--------------------------------------
02 po             19 .              46 ri             85 s
06 pas            24 que            47 ro             89 te
09 pour           26 qui            49 rou            95 tu
11 par            31 y              50 ru             97 tout
12 plus           34 qu'il          53 roit           00 ter
14 paix           35 laquelle       69 se             69 se
15 per            43 ra             71 si             89 te
17 .              44 re             75 su
The groups surmounted by a tilde (~)
------------------------------------
01 de             16 en             46 fait           68 guerre
05 du             25 et             59 ge             94 ie
06 dans           31 estoit         66 gens           98 guerre
08 des
The groups surmounted by a circumflex accent (^)
------------------------------------------------
02 tion           14 ver            18 voi            29 votre
04 tant           16 vio            19 vou            98 des
The groups surmounted by a backslash (\)
----------------------------------------
39 au             73 ce             78 cou            83 cour
42 autre          75 ci             79 cu             95 da
64 bu             76 ci             81 con            98 de
68 le

Translation of the letter, the plaintext

To be able to process the encrypted letter by computer, I replaced the tags with a number that I prefixed to the group. Here are the numbers (0-6) I used:

	0xxx		For untagged groups
	1xxx		The groups surmounted by « // » (double slash)
	2xxx		The groups surmounted by « - » (hyphen)
	3xxx		The groups surmounted by « ¨ » (umlaut) 
	4xxx		The groups surmounted by « ~ » (tilde)
	5xxx		The groups surmounted by « ^ » (circumflex accent)
	6xxx		The groups surmounted by « \ » (backslash)

Here is the group-by-group translation of the beginning of the letter using the previous convention:

  1: 201. 267. 102. 344. 156. 344. 369. 114. 389. 102.
     il   nous a    re   p    re   se   n    te   a 
     312. 494. 140. 118. 138. 344. 116. 346. 369.
     plus ie   u    r    s    re   p    ri   se 
  

  2: 138. 334.  265. 639. 353. 306. 243. 106. 114. 698.
     s    qu'il ny   au   roit pas  moy  e    n    de
     120. 343. 110. 389. 118. 110. 675. 216. 314.
     t    ra   i    te   r    i    ci   en   paix
   

  3: 371. 231. 162. 431.   315. 299. 395. 106. 113. 219.
     si   on   y    estoit per  pe   tu   e    l    le 
     249. 120. 349. 112. 219. 311. 219. 112.
     ment t    rou  b    le   par  le   b
  

  4: 350. 110. 120. 598. 019. 102. 118. 246. 324. 246.
     ru   i    t    des  ???  a    r    mes  que  mes 
     239. 201. 369. 353. 110. 132. 302. 138. 371.
     mes  il   se   roit i    m    po   s    si   ...

Here is finally the reconstruction of the plaintext:

Il nous est présenté à plusieurs reprises qu'il n'y auroit pas moyen de traitter icy, si l'on estoit perpétuellement troublé par le bruit des armes, que mesmes il seroit impossible de subsister si tout ce qui fait le pays de Nimègue n'estoit à couvert des courses et des violences des gens de guerre que nous y avions autant d'interest que tous les autres ambassadeurs et qu'il nous prioit de le représenter à Votre Majesté qu'il s'y avoit encore aucune contribution establie dans toute l'estendue du pays pour lequel on demande cette neutralité et qu'ainsy elle n'y perdroit rien en accordant cette condition sans laquelle il n'y avoit pas lieu de croire que les ambassadeurs et Ministres des Princes et de leurs Alliés voulussent se rendre icy.

The English translation:

It is presented to us on several occasions that there would be no way of dealing here, if we were perpetually disturbed by the noise of arms, that even it would be impossible to subsist if all that makes the country of Nijmegen were not safe from the incursions and violence of the soldiers that we had as much interest in it as all the other ambassadors and that he begged us to represent it to Your Majesty that there was still no established contribution in the whole extent of the country for which this neutrality is requested and that thus it would lose nothing by granting this condition without which there was no reason to believe that the ambassadors and Ministers of the Princes and their Allies wanted to get here.

Note that this code is very similar to the 1684 code described later. The main difference being the use of tags instead of just using number groups.

References

L’art de deschiffrer, traité de déchiffrement du XVIII siècle de la Secrétairie d’état et de Guerre Espagnole. Edité par J.P. Devos, 1907, Louvain, p 72.