At a glanceKey from adjacent plaintext · complete
- The letter
- J. C. Smissaert, secretary of the Raad der Aziatische Bezittingen (the Dutch Asiatic Council), to C. J. Prediger, then at Batavia, 20 November 1800, “Geacht vriend”: 14 lines carry cipher, 60 cipher words in all.
- Where
- Nationaal Archief, The Hague, 2.01.27.02 (Raad der Aziatische Bezittingen en Etablissementen), inv. 209, scan 0002 (right-hand page); the clear minute is on scans 0001, 0002 (left) and 0004. Not on DECODE and not in the catalogue.
- The cipher
- A simple substitution of letters for Dutch. Each letter is a column of two digits, a top digit 1–7 over a bottom digit 1–4. Only the sensitive words are enciphered, and word division is kept.
- How the key was found
- Under a protocol Brice Dudout fixed in advance, his AI agents aligned lines 1 to 12 with the clear minute, built the key by script and froze it, then measured it once on lines 13 and 14: 0.933 of the characters against at best 0.433 for 200 shuffled keys. The project did not repeat the test and did not see the images.
- What it says
- Besides the long-delayed shipment of troops to the Indies, the Council has been authorised to prepare a second expedition to Batavia from another place in Europe; Prediger is to tell the Governor-General in secrecy. The content is the minute’s, not new.
- Still open
- The rest of the minute and the postscript are not transcribed; one AI reader, no human check of the digit columns; q is not seen and f rests on one word.
- Credit
- The transcription, the key and its test are Brice Dudout’s (L’Europe chiffrée, with Claude Opus 5.5 agents). The clear text is the minute of 1800.
01 The letter and its minute
Inventory number 209 of the archive of the Raad der Aziatische Bezittingen en Etablissementen (Nationaal Archief, The Hague, 2.01.27.02) has five scans. The archive’s description already names the encipherment (“overbrenging in cijfer”) together with the minute. The contributor, Brice Dudout (L’Europe chiffrée, with Claude Opus 5.5 agents), reports finding the file in his own sweep of the Nationaal Archief on 2 November 2026 and worked on it on 9 November 2026. The project’s first sweep of the Nationaal Archief (23 October 2026, research/nationaal_archief) had already listed the item from the inventory, without working on it. The inventory’s title describes a secret missive written by order of the Council to C. J. Prediger, councillor of the Indies at Batavia, by the Council’s secretary, Mr. J. C. Smissaert, with the encipherment attached and a later postscript added to a triplicate sent on 20 April 1801.
| Scan | Content | Role |
|---|---|---|
| 0001, 0002 (left), 0004 | The clear minute of the letter. The passages to encipher are underlined, with small strokes under them that count the letters; a postscript follows. | The plaintext |
| 0002 (right) | The letter in partial cipher, “Geacht vriend”, 20 November 1800: 14 lines with cipher, 60 cipher words. The contributor calls it the letter as sent; the inventory calls it the attached encipherment. | The ciphertext |
| 0003 | Blank verso (show-through of 0002). | None |
| 0005 | End of the postscript, “Amst. 20 april 1801”, signed Smissaert (seen by the contributor as a thumbnail only). | Clear |
There is no cipher in the file without its clear text. The content has always been readable in the minute, and nothing here is claimed as a new text. What the contributor adds is the key as a table, and the check that the cipher page matches the underlined passages of the minute, which the inventory already files together. He found no printed edition of the letter and no study of the cipher (two web searches), and no entry for it in this project’s catalogue, leads, targets, issues or pull requests.
No image is shown on this page. The inventory record offers the scans for download but states no licence, so the contributor included none and the project has not reproduced any; the first words of the held-out passage are printed as digits in the strip under the title.
02 The key and its test
Each cipher letter is written as a column of two digits, one above the other. The top digit runs from 1 to 7 and the bottom digit from 1 to 4, so the alphabet fits a grid of seven rows and four columns. The transcription writes a column as top digit then bottom digit (61 is 6 over 1). The letter has 375 such columns.
| top \ bottom | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| 1 | h | r | – | l |
| 2 | v | m | i/j | u |
| 3 | y | z | c | p |
| 4 | t | k | s | a |
| 5 | b | g | o | f |
| 6 | e | d | w | x |
| 7 | n | – | – | – |
The contributor wrote his protocol and hashed it after the cipher was transcribed and before the clear minute was opened. The learning part is lines 1 to 12, aligned word by word with the minute. The key was built by script as the majority letter for each code: 23 codes, with no conflict. It was frozen before the clear text of the held-out lines was opened. The held-out part is lines 13 and 14, 60 letters (“Heer Gouverneur Generaal zulks in secretesse gelieft te communiceren”), hashed before learning.
One measurement was made. The frozen key gives 0.933 of the characters of the minute’s text for that passage, against at best 0.433 for 200 shuffled keys (a margin of 0.500), with a value in the key for 0.983 of the held-out columns. The thresholds, 0.85 for the score and 0.30 for the margin, were fixed in advance, so the key counts as validated by the contributor’s protocol. The differences that remain are the encipherer’s 42 (k) written for s in “secretesse” and the code 54, which the learning part never shows. 54 = f was added to the key after the measurement, from the held-out word “gelieft” only.
The contributor declared two reservations before the freeze. Two copying slips in the learning part were corrected from the raw notes taken before the clear text was opened; the held-out lines were not changed. And the crop of scan 0001 used for learning also showed the next two lines of the minute, where the beginning of the held-out clear text was seen. The test is therefore not blind on those words. It stays mechanical: the key comes by script from the learning alignments only, with no value added by hand.
This is the contributor’s test, re-run by him from the frozen files on 9 November 2026 with the same figures. The project did not repeat it and did not see the images.
03 The reading
Of the 60 cipher words the contributor counts 54 as certain, 3 as probable and 3 as restored, with none unresolved: 57 of 60 (0.95) with the restorations left out, 60 of 60 with them. All six doubtful words are confirmed by the minute. In the text below the cipher passages are in italics; {x} is a probable word and [x] a restored letter.
Geacht vriend! Behalven de U bekende en vóór uw vertrek reeds geprojecteerde verzending van een corps troepen voor Indie, welke door veele tegenspoeden tot hiertoe opgehouden is geweest, maar evenwel, zoo wij hopen, eerlang voortgang zal hebben, is de Asiatische Raad geautoriseerd en reeds bezig met de arrangementen tot eene {andere} [s]oortgelyke expeditie te vertrekken naar Batavia uit eenen anderen oort van Eur[o]pa, waardoor, indien deselve reusseerd, eene aanzienlyke ver[ste]rking der militaire magt voor Java zal worden aangebragt. Ik ben gelast U daar van deze onderhandsche en voorlopige kennis te geven, met verzoek, dat Gij den Heer Gouverneur Generaal zulks in {secretesse} {gelieft} te communiceren tot deszelfs vertrek. Mijne bezigheden laten mij niet toe meer …
In the contributor’s English translation: “Esteemed friend! Besides the sending of a corps of troops to the Indies, known to you and already planned before your departure, which through many setbacks has been held up until now but which, as we hope, will nevertheless go forward before long, the Asiatic Council is authorised, and already busy with the arrangements for another, similar expedition to leave for Batavia from another place in Europe, by which, if it succeeds, a considerable reinforcement of the military force for Java will be brought. I am instructed to give you private and preliminary notice of this, with the request that you be pleased to communicate it in secrecy to the Governor-General until his departure. My occupations do not allow me more …”
04 What remains uncertain
The contributor grades words as certain, probable or restored; the grades below are his.
- Probable: {secretesse}, enciphered k-e-c-r-e-t-e-k-k-e, with 42 (k) written for s three times, a slip of the encipherer.
- Probable: {gelieft}, the only occurrence of 54 = f.
- Probable: {andere}, which is followed by a stray 44 (a).
- Restored: Eur[o]pa, the top digit of the o is illegible; [s]oortgelyke, the first column is struck out; ver[ste]rking, where the encipherer wrote “verking” and left out three letters.
- The key has no value for q, which was not seen in the letter; cells 13, 72, 73 and 74 of the grid are empty.
- The clear minute is transcribed only where it pairs with the cipher and for the letter’s opening. The rest of the minute and the postscript (scans 0004 and 0005) are not transcribed; this was not attempted.
- One reader, an AI agent, read the digit columns. No human palaeographer checked them, and the project did not see the images.
- The held-out test is not blind on the first words of its passage, as declared above.
The contributor also looked for other cipher near this one: inv. 209 holds no other, and the 1811 Janssens despatches (Nationaal Archief 2.01.27.05 inv. 12) use another system, a numeric code in French.
Full texts
The transcription and the decryption of every document on this page, so that the reading can be used and checked. Short files are shown here; all are in the repository.
Smissaert to Prediger, 20 Nov 1800, the letter as sent (scan 0002)
Besides the long-delayed troop shipment to the Indies, the Asiatic Council has been authorised to prepare a second, similar expedition to Batavia from another place in Europe, which would considerably reinforce the military on Java; Prediger is to tell the Governor-General in secrecy.
Transcription
# batavia1800: cipher passages of the letter J. C. Smissaert -> C. J. Prediger, 20 Nov 1800 (Nationaal Archief, The Hague, 2.01.27.02 inv. 209, scan 0002, right-hand page). # Each cipher letter is a column of two digits, written one above the other (top 1-7, bottom 1-4); here written as "top+bottom" (61 = 6 over 1). # One cipher word per "/" group; x = a column struck out or illegible; ?3 = top digit illegible, bottom 3. Clear words between the groups are not repeated here. # Lines L01-L12 = learning part A; L13-L14 = held-out part H (frozen/H-CHIFFRE.txt). Version 2 (frozen/AMENDEMENT-01.md): two copying slips in A corrected from the raw notes, H unchanged. L01 52 61 34 12 53 23 61 33 41 61 61 12 62 61 / 21 61 12 32 61 71 62 23 71 52 / 21 44 71 / 61 61 71 / 33 53 12 34 43 L02 41 12 53 61 34 61 71 / 21 53 53 12 23 71 62 23 61 / 63 61 14 42 61 / 62 53 53 12 21 x 61 61 14 61 L03 41 61 52 61 71 43 34 / 53 61 62 61 71 41 53 41 / 11 23 61 12 / 41 53 61 / 53 34 52 61 11 53 24 62 61 71 / 23 43 L04 x 52 61 63 61 61 43 41 L05 21 53 53 12 41 52 44 71 52 / 32 44 14 / 11 61 x 51 51 61 x 71 L06 52 61 44 24 41 53 12 23 43 61 61 12 62 / 62 61 L07 44 12 12 44 71 52 61 22 61 71 41 61 71 / 41 53 41 / 61 61 71 61 / 44 71 62 61 12 61 44 / x 53 53 12 41 52 61 L08 14 31 42 61 / 61 64 34 61 62 23 41 23 61 / 41 61 / 21 61 12 41 12 61 42 42 61 71 71 44 44 12 L09 51 44 41 44 21 23 44 / 24 23 41 / 61 61 71 61 71 / 44 71 62 61 12 61 71 / 53 53 12 41 / 21 44 71 / 61 24 12 ?3 34 44 L10 12 61 24 43 43 61 61 12 62 / 61 61 71 61 / 44 44 71 32 23 61 71 L11 14 31 42 61 / 21 61 12 42 23 71 52 62 61 12 / 22 23 14 23 41 44 23 12 61 / 22 44 52 41 21 53 53 12 23 44 21 44 L12 32 44 14 / 63 53 12 62 61 71 / 44 44 71 52 61 51 12 44 52 41 L13 11 61 61 12 / 52 53 24 21 61 12 71 61 24 12 / 52 61 71 61 12 44 44 14 / 32 24 14 42 43 / 23 71 L14 42 61 33 12 61 41 61 42 42 61 / 52 61 14 23 61 54 41 / 41 61 / 33 53 22 22 24 71 23 33 61 12 61 71
Decryption
# batavia1800: decryption, line by line, with key.tsv (frozen key + 54 = f). ? = no value (x, ?3). Word divisions are the groups of the transcription. L01 geproiecteerde verzending van een corps L02 troepen voorindie welke doorv?eele L03 tegensp oedentot hier toe opgehouden is L04 ?geweest L05 voortgang zal he?bbe?n L06 geautoriseerd de L07 arrangementen tot eene anderea ?oortge L08 lyke expeditie te vertrekkennaar L09 batavia uit eenen anderen oort van eur?pa L10 reusseerd eene aanzien L11 lyke verkingder militaire magtvooriava L12 zal worden aangebragt L13 heer gouverneur generaal zulks in L14 kecretekke gelieft te communiceren
Reading
# batavia1800: reading of the letter Smissaert -> Prediger, 20 November 1800
Nationaal Archief, The Hague, 2.01.27.02 (Raad der Aziatische Bezittingen en Etablissementen), inv. 209, scan 0002
(right-hand page, the letter as sent in partial cipher); clear minute of the same letter on scans 0001, 0002 (left) and 0004.
Marks: cipher passages in *italics*, the rest is clear on the page; {x} = probable; [x] = restored; ‹…› = unresolved (none).
## Text (Dutch, 1800)
Geacht vriend! Behalven de U bekende en vóór uw vertrek reeds *geprojecteerde verzending van een corps troepen voor
Indie, welke door veele tegenspoeden tot hiertoe opgehouden is geweest*, maar evenwel, zoo wij hopen, eerlang *voortgang
zal hebben*, is de Asiatische Raad *geautoriseerd* en reeds bezig met *de arrangementen tot eene {andere} [s]oortgelyke
expeditie te vertrekken naar Batavia uit eenen anderen oort van Eur[o]pa*, waardoor, indien deselve *reusseerd, eene
aanzienlyke ver[ste]rking der militaire magt voor Java zal worden aangebragt*. Ik ben gelast U daar van deze
onderhandsche en voorlopige kennis te geven, met verzoek, dat Gij den *Heer Gouverneur Generaal zulks in {secretesse}
{gelieft} te communiceren* tot deszelfs vertrek. Mijne bezigheden laten mij niet toe meer ...
## Translation (English)
Esteemed friend! Besides the *sending of a corps of troops to the Indies*, known to you and already *planned* before your
departure, *which through many setbacks has been held up until now* but which, as we hope, will nevertheless *go
forward* before long, the Asiatic Council is *authorised*, and already busy with *the arrangements for another, similar
expedition to leave for Batavia from another place in Europe*, by which, if it *succeeds, a considerable reinforcement of
the military force for Java will be brought*. I am instructed to give you private and preliminary notice of this, with
the request that you *be pleased to communicate it in secrecy to the Governor-General* until his departure. My
occupations do not allow me more ...
## Count (cipher words only: 60)
- certain: 54
- probable {x}: 3
- {secretesse}: enciphered k-e-c-r-e-t-e-k-k-e, with 42 (k) written for s three times (encipherer's slip);
- {gelieft}: the only occurrence of 54 = f;
- {andere}: followed by a stray 44 (a).
- restored [x]: 3
- Eur[o]pa: top digit of the o illegible;
- [s]oortgelyke: first column struck out;
- ver[ste]rking: the encipherer wrote "verking", omitting three letters.
- unresolved: 0
- read share (certain + probable, restored excluded): 57/60 = **0.95**. With the restorations, which the clear minute
confirms: 60/60.
The minute marks every passage to be enciphered by underlining it, with small vertical strokes under it that count the
letters. Only those passages are in cipher; the rest of the letter is clear on the sent page.
## Note on the content
The text is not new: the clear minute of the same letter is filed with it (the pair). What is new is the key, rebuilt
from the minute and validated on a held-out passage (validation.txt).Translation
# batavia1800: reading of the letter Smissaert -> Prediger, 20 November 1800
Nationaal Archief, The Hague, 2.01.27.02 (Raad der Aziatische Bezittingen en Etablissementen), inv. 209, scan 0002
(right-hand page, the letter as sent in partial cipher); clear minute of the same letter on scans 0001, 0002 (left) and 0004.
Marks: cipher passages in *italics*, the rest is clear on the page; {x} = probable; [x] = restored; ‹…› = unresolved (none).
## Text (Dutch, 1800)
Geacht vriend! Behalven de U bekende en vóór uw vertrek reeds *geprojecteerde verzending van een corps troepen voor
Indie, welke door veele tegenspoeden tot hiertoe opgehouden is geweest*, maar evenwel, zoo wij hopen, eerlang *voortgang
zal hebben*, is de Asiatische Raad *geautoriseerd* en reeds bezig met *de arrangementen tot eene {andere} [s]oortgelyke
expeditie te vertrekken naar Batavia uit eenen anderen oort van Eur[o]pa*, waardoor, indien deselve *reusseerd, eene
aanzienlyke ver[ste]rking der militaire magt voor Java zal worden aangebragt*. Ik ben gelast U daar van deze
onderhandsche en voorlopige kennis te geven, met verzoek, dat Gij den *Heer Gouverneur Generaal zulks in {secretesse}
{gelieft} te communiceren* tot deszelfs vertrek. Mijne bezigheden laten mij niet toe meer ...
## Translation (English)
Esteemed friend! Besides the *sending of a corps of troops to the Indies*, known to you and already *planned* before your
departure, *which through many setbacks has been held up until now* but which, as we hope, will nevertheless *go
forward* before long, the Asiatic Council is *authorised*, and already busy with *the arrangements for another, similar
expedition to leave for Batavia from another place in Europe*, by which, if it *succeeds, a considerable reinforcement of
the military force for Java will be brought*. I am instructed to give you private and preliminary notice of this, with
the request that you *be pleased to communicate it in secrecy to the Governor-General* until his departure. My
occupations do not allow me more ...
## Count (cipher words only: 60)
- certain: 54
- probable {x}: 3
- {secretesse}: enciphered k-e-c-r-e-t-e-k-k-e, with 42 (k) written for s three times (encipherer's slip);
- {gelieft}: the only occurrence of 54 = f;
- {andere}: followed by a stray 44 (a).
- restored [x]: 3
- Eur[o]pa: top digit of the o illegible;
- [s]oortgelyke: first column struck out;
- ver[ste]rking: the encipherer wrote "verking", omitting three letters.
- unresolved: 0
- read share (certain + probable, restored excluded): 57/60 = **0.95**. With the restorations, which the clear minute
confirms: 60/60.
The minute marks every passage to be enciphered by underlining it, with small vertical strokes under it that count the
letters. Only those passages are in cipher; the rest of the letter is clear on the sent page.
## Note on the content
The text is not new: the clear minute of the same letter is filed with it (the pair). What is new is the key, rebuilt
from the minute and validated on a held-out passage (validation.txt).Key: key.tsv
05 Sources
- Nationaal Archief, The Hague, 2.01.27.02, Inventaris van de archieven van de Raad der Aziatische Bezittingen en Etablissementen, 1800–1806, inv. 209, five scans; the images are not reproduced here.
- Brice Dudout, the target folder: the transcription, the key, the frozen protocol and measurement, and the reading with its translation.
The notes, the key, the transcription, the reading and the frozen test files are in targets/batavia1800.
Cite this page
Daniel Bourdeau and Brice Dudout, “Smissaert to Prediger, 20 November 1800”, Cyphersolver, posted 9 November 2026, https://cyphersolver.com/batavia1800.html.