Telegraph codes of the US War Department and States Department in the late 19th century are described in other articles. The Navy Secret Code of 1887 is discussed by participants at a German cryptology blog (Klausis Krypto Kolumne) and is briefly described below.
It is described by William F. Friedman, who was given permission to consult the actual code books preserved in Navy Security archives (Friedman Lectures on Cryptology (pdf) p.93-94, 101-102).
The code is titled The U.S. Navy Secret Code and was used from December 1887. It was accompanied by The Book of Key Words and General Geographical Tables.
When encoding a message with this system, the first step is to use the basic code book (The U.S. Navy Secret Code) to encode the message with 6-digit figures. Then, the sequence of 6-digit figures are regrouped into 5-digit groups, which are converted to "outlandish" code words with the cipher book (presumably, The Book of Key Words). Use of such "outlandish" words as code words was a common practice in telegraphy at the time (see another article).
Friedman demonstrates the decoding process of an actual message.
On 15 February 1898, US Battleship Maine was blown up in Havana, Cuba (Wikipedia). Theodore Roosevelt, Assistant Secretary of the Navy (and future president), acted for preparing the navy during the temporary absence of the Secretary of the Navy and sent the following telegram on 26 February 1898 to Admiral Dewey at Hong Kong. It was two months before the declaration of war that began the Spanish-American War.
To read the telegram, first, the "cipher book" is used to translate these outlandish words into 5-digit figures.
WASSERREIF | 99055 |
PAUSATURA | 62399 |
BADANADOS | 11005 |
CENTENNIAL | 16820 |
TITUBANDI | 90000 |
LOSCHBANK | 52390 |
VOVETE | 98242 |
OFFENSADO | 59841 |
CRAQUIEZ | 21992 |
PICARAZADO | 64004 |
NUMERATURA | 58639 |
SPOILABLE | 83607 |
APPILANTI | 07319 |
DEPUGNERE | 25545 |
DEMIDEVIL | 24980 |
MONOSILABO | 56346 |
ATOCHARON | 09599 |
TACHONASEN | 87782 |
ALIENATOTE | 04665 |
CRENCHA | 22099 |
SPARRWERKE | 83000 |
Since the basic code book employs a 6-digit system, the sequence of 5-digit figures thus obtained is regrouped into 6-digit figures.
Now, the basic code book can be used to recover the plaintext.
990556 | SECRET AND CONFIDENTIAL |
239911 | ORDER THE SQUADRON |
005168 | EXCEPT |
209000 | THE MONOCACY |
052390 | TO HONGKONG, CHINA |
982425 | KEEP FULL OF COAL |
984121 | IN THE EVENT OF |
992640 | DECLARATION OF WAR |
045863 | SPAIN |
983607 | IT WILL BE YOUR DUTY TO SEE THAT |
073192 | THE SPANISH SQUADRON |
554524 | DOES NOT LEAVE |
980563 | ASIATIC COAST |
460959 | AND THEN |
987782 | OFFENSIVE OPERATION(S) |
046652 | IN PHILIPPINE ISLANDS |
209983 | KEEP OLYMPIA UNTIL FURTHER ORDERS |
Representing a word into a number and then regrouping the sequence of digits to find a code word for transmission is used in a commercial code book well-known as Slater's Code (see another article). In one of its many superencipherment schemes ("Example IV") described in its introduction, words "The Queen ..." are converted to 5-digit figures (22313 18095 ...), which are then regrouped into 4-digit figures (2213 3180 9512 ...), by which code words for transmission (begged bulging freak ...) are found.
Slater's Code, including the examples in the introduction, was used as a basis for a telegraph code of the War Department in 1885 with only a minor adaptation (see another article).
By sorting the lists in the above, we may reconstruct a very small portion of the code.
The basic code book:
(basic vocabulary) | ||
005168 | EXCEPT | |
045863 | SPAIN | |
(location) | ||
046652 | IN PHILIPPINE ISLANDS | |
(destination) | ||
052390 | TO HONGKONG, CHINA | |
(expressions about fleet) | ||
073192 | THE SPANISH SQUADRON | |
209000 | THE MONOCACY | |
209983 | KEEP OLYMPIA UNTIL FURTHER ORDERS | |
239911 | ORDER THE SQUADRON | |
(common phrases) | ||
460959 | AND THEN | |
554524 | DOES NOT LEAVE | |
(expressions about military operations) | ||
980563 | ASIATIC COAST | |
982425 | KEEP FULL OF COAL | |
983607 | IT WILL BE YOUR DUTY TO SEE THAT | |
984121 | IN THE EVENT OF | |
987782 | OFFENSIVE OPERATION(S) | |
990556 | SECRET AND CONFIDENTIAL | |
992640 | DECLARATION OF WAR | |
Considering that Slater's Code had 25000 entries, the size typical at the time, a million entries seems too large. There may have been many blanks.
The cipher book:
ALIENATOTE | 04665 |
APPILANTI | 07319 |
ATOCHARON | 09599 |
BADANADOS | 11005 |
CENTENNIAL | 16820 |
CRAQUIEZ | 21992 |
CRENCHA | 22099 |
DEMIDEVIL | 24980 |
DEPUGNERE | 25545 |
LOSCHBANK | 52390 |
MONOSILABO | 56346 |
NUMERATURA | 58639 |
OFFENSADO | 59841 |
PAUSATURA | 62399 |
PICARAZADO | 64004 |
SPARRWERKE | 83000 |
SPOILABLE | 83607 |
TACHONASEN | 87782 |
TITUBANDI | 90000 |
VOVETE | 98242 |
WASSERREIF | 99055 |
The telegram presented at Klausis Krypto Kolumne is the one sent from Commodore Dewey to Secretary Long.
(There was no trans-pacific submarine cable until the next century (Wikipedia). Dewey's report was delivered by revenue cutter McCulloch (Wikipedia) on 7 May to the US consul at Hong Kong (Kahn p.254), who forwarded it by cable via Europe.)
The following lists the code groups sorted in alphabetical order.
ABHORREBAM ABRIPIEBAR ACCULATO ADHIBEBIT AGOURADA ALDERMEN ALEXICACIO APICULATED APPACIO ARGEMONE ASCHUCHARON ASEMEJAR ASOMBRAR |
BLUTNUSS BOWLINE BRANDAL BRANDBLASE BRICOLAMES BROMIDO CONLUCETUR CRAQUEREZ CRASENZA CRISUELA DEARTUAREM DECRUSAMES DEFENSABIS |
ECLUSIEZ ECUMENICAL EDIFIERS EDITASEN ENTOILERAI EXCALDABOR FLEMINGS FORTNIGHT GALEFFAVA GAMETRIA GAMETRIA GEFLOGEN GENIAZO |
GIFTMORD GLADIATOR GOLDKRAUT GROWLS HAMAXANDOS HEXAPLA HONEYGUIDE IMPAVIDEZ IMPAZZAVA INCLEMENTE INCLEMENTE INTRUSIVE |
LAVATORIO MENGSPATH MORINGA MUGIOLINO OMBRAGE PEZADA PEZADA PRENSABERE REFRENANS REGENBUI RETAPIEZ RIBOTIEZ RIONORAI |
ROSOBODA SANSCRITO SAUKNOTEN SCHRATTEL SCHULPROBE SETULOSE SIGNIFICAR SILBATO SQUILLANDO STIRRING SUMPTER SUPERFICIE SUSPIRARAS |
TODESBILD TRUNCARDES TURLERIN ULTIMAMUS UNTERHEBEN UNTERHEFE VIJFVOETIG VORHASCHEN WATERTHIEF WEIBERRATH |
This message is presented in David Kahn, The Codebreakers, p.254. This is a report of the Battle of Manila Bay on 1 May 1898, in which Commodore Dewey destroyed the Spanish Pacific squadron (Wikipedia). The plaintext begins as follows.
Richard W. Peuser, "Documenting United States Naval Activities During the Spanish-American War", Prologue, National Archives. In particular, "Record Group 45" is the source used by David Kahn, who says there are other code message with their plaintexts and reproduces one (p.1019, 253).
According to History of Communications-Electronics in the United States Navy by Captain Linwood S. Howeth, USN (Retired), 1963, pp.289-296 (online), there was also a 1908 edition. As of World War I, both the 1887 and 1908 editions were considered to have been compromised but the latter was used in a limited way.