Tag Archive | ciphers

Ch-Ch-Ch-Changes!

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mssEC_24_076

Chicago 21
Sheldon
I thank you for
the suggestion the printer
is now at work
printing arbitraries for months and
hours and which will be
pasted inside cover of book
I designate arbitraries as follows
hamlet for James Hebrew for Pamunky
valley for Brigadier vernon for General
venus Colonel Vienna Major virtue Captain
vulture lieutenant Vincent quartermaster violet paymaster
vista surgeon how you like it

The codebooks used in the Civil War evolved as time went on, as is evident in this telegraph. The updates here correspond to copies of Cipher, or Code, Book 9, which has gaps in the arbitraries even after these additions. Half of the “P” section, most of “T”, and all of “U” are still unassigned, so there was still room for expansion of the code if needed. We will be recording these unassigned arbitraries as we will the assigned ones (e.g. Hamlet = James, Vernon=general, Pacific=[none]) so that we will have a complete data set when it comes time to decode the messages.

Keeping Secrets, Part 2: Route Ciphers

 

By Daniel Stowell, Director and Editor of the Papers of Abraham Lincoln at the Abraham Lincoln Presidential Library and Museum.

MaintainAvatar_Image.jpging the secrecy of high-level political and military communications during the American Civil War was a necessity for both the Union and the Confederacy.  In the previous post, we learned that the Union had the advantage of a simple but ingenious system developed by Anson Stager, the civilian superintendent of the Western Union Company in Ohio.  Early in the war, Stager developed a cipher system for use by the governor of Ohio and Union generals in the area.  When he became the head of the United States Military Telegraph in October 1861, Stager brought his cipher system with him and used it throughout the Union high command.

Stager’s system depended on absolute secrecy, and not even top civilian or military officials were allowed to see the cipher codes.  The cipher Stager developed relied on two key principles.  First, a cipher telegrapher replaced key nouns and verbs for persons, places, and military terms with arbitraries, or code words, known only to his counterpart at the other end of the telegraph line.  Although this technique was effective, so long as the cipher remained absolutely secret, over time, dedicated Confederate agents who intercepted such messages might be able to guess at the true meaning of many or most arbitraries.

However, Stager’s system had another key component.  It was also a sophisticated “route cipher.”  At its simplest, a route cipher simply reorders the words in a message from their ordinary reading order.  For example, a backwards route would simply reverse the order of all words in the message, and the recipient could read the message from the end to the beginning to understand it.  The system employed by the Union during the American Civil War was substantially more complicated.mssEC_41_014 cropped.jpg

The key to decoding a route cipher is to place the words in the proper number of rows and columns, similar to a modern-day spreadsheet.  The key unit in Stager’s system was the word, not the letter.  So, a cipher telegrapher would take a message and write it out in a series of rows and columns.  If the message did not end on the last column of the last row, he would add additional “null words” to fill out the grid.  These null words could be nonsense or they could even send a short message to his counterpart on the other end of the line, such as “Nab those Rebs” and “Rained nicely tonight.”

After the message was arranged in a grid, the cipher telegrapher chose a route through the grid to reorder the words.  For example, if the message was 10 columns wide by 11 rows long, then the cipher telegrapher could use the commencement word “Morton” (among others) to indicate that the message had 10 columns and the commencement words “Next” or “News” to indicate that it had 11 rows (2 rows + 9 rows).  The receiving cipher telegrapher consulted his cipher 1 code book and knew that the incoming message of 110 words should be arranged in 10 columns and 11 rows.  Then, he placed the words in their proper order by reading the route indicated in cipher 1: down the sixth column, down the tenth column, up the first column, down the eighth column, up the second column, down the fourth column, up the seventh column, down the third column, up the fifth column, and down the ninth column.

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Reading the words in this manner placed them in their proper order, but the receiving cipher telegrapher still needed to replace the arbitraries in the message with their clear counterparts, either words or punctuation.  The telegrapher also stripped out the commencement words and the null words to leave only the words of the message.

The scrambling of words through the route cipher method made Stager’s system far more difficult to decipher than using arbitraries alone.  In fact, the Confederates never broke any of the Union ciphers, and the ability for political and military leaders to communicate important information securely was important to the overall success of the Union war effort.

Fortunately for researchers, none of the telegrams in the Thomas T. Eckert Papers are scrambled in the route in which they were originally sent.  Even those with arbitraries for words and punctuation are in their proper order, making decoding them a much simpler task than Confederate agents faced in the 1860s.

Keeping Secrets, Part 1: Arbitraries

By Daniel Stowell, Director and Editor of the Papers of Abraham Lincoln at the Abraham Lincoln Presidential Library and Museum.

Keeping secrets from the enemy is vital to combatants in any war, and the American Civil War is no exception.  Union and Confederate leaders sent directions to and received reports from their subordinates over wide areas.  The telegraph made “lightning” communication between distant points possible.  Leaders who could use it effectively had a decided advantage, both on the battlefield and in mobilizing their society’s resources for war.

The simple substitution of words or letters for other words or letters is an ancient technique for keeping messages private between the sender and the recipient.  Lovers sent messages to each other in their own private codes, and diplomatic and military leaders also sent messages that messengers or interceptors could not understand.  Critical to transmitting such messages successfully was that both parties knew and understood the code and that the encoded message made it safely between them, usually by a personal courier or perhaps even by mail.  The development of the telegraph complicated the private transmission of messages, because anyone along the line of communication could tap the line and intercept the series of dots and dashes that were used to transmit messages over the wires.  In wartime, messages traveling hundreds of miles were often intercepted by enemy agents.

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Anson Stager (photo from Library of Congress)

The fact that Confederates could often intercept Union messages sent by telegraph made encoding important messages critical to the success of the Union war effort.  At the outbreak of the American Civil War, the governor of Ohio asked Anson Stager, the civilian superintendent of the Western Union Company, to manage telegraph operations in southern Ohio and along its border with (West) Virginia.  Stager developed a cipher, or code, with which the governor of Ohio could communicate secretly with the governors of Indiana and Illinois.  General George B. McClellan also used the cipher when he was leading a Union army in western Virginia.  When Stager became head of the Military Telegraph Department in Washington in October 1861, the Union Army put the components of Stager’s cipher into widespread use.

mssEC_46_005_printed_tp cropped small.jpgThe key to the success of Stager’s cipher was absolute secrecy.  Typically, fewer than a dozen people had access to any cipher.  These small books became the most important piece of property traveling with an army.  Even commanding generals and other telegraphers did not have access to the cipher code.  Large armies in the field generated thousands of telegrams, and only a minority of the most important were sent in cipher.  The cipher telegrapher had to encode and decode any message sent in cipher himself.  Once encoded, he could have another telegrapher send the message because the other telegrapher was only sending a series of words, without understanding their meaning.  Similarly, a telegrapher could receive a telegram in cipher, then pass it along to the cipher telegrapher for decoding.

In addition, the War Department used multiple ciphers simultaneously, so different armies communicated highly sensitive materials to Washington using different codes.  Only the cipher telegraphers in the War Department knew which codes were used by which armies.  If a cipher telegrapher were captured by the enemy, as happened at least once, the telegraphers switched to a different cipher to communicate with that army.

Like messages for thousands of years, Union cipher telegrams used word substitution to obscure the meaning of the message.  Stager developed code words for times of day; important political and military leaders, from both the Union and the Confederacy; cities, states, and rivers; and important military terms.  Substituting arbitraries, or code words, for key words in a message made them difficult to understand.  In addition, Stager added arbitraries for punctuation.  In Cipher No. 1, for example, “pedlar” and “Pekin” were arbitraries for a comma, and “star” was an arbitrary for the word “interrogation” or a question mark, depending on context.  “Unity,” “zodiac,” and “zebra” were arbitraries for a period.

For frequently mentioned persons, multiple arbitraries referred to a single person.  For example, in Cipher 9, used from late 1862 to mid-1864, the arbitraries for President Abraham Lincoln were “Adam” or “Asia.”  In Cipher 1, used from mid-1863 through the end of the war, arbitraries for Lincoln included “Bologna,” “Bolivia,” “Ida,” “ink,” “Irving,” “ingress,” “ingrate,” and “ingot.”  Only the cipher telegrapher would know that any of those eight arbitraries referred to President Lincoln.

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The use of arbitraries in cipher messages provided a great deal of security for important messages, but arbitraries might only replace 10 to 20 percent of the key nouns and verbs in a message.  Through careful study, Confederates might have been able to decipher one or more of the Union ciphers, but Stager’s system had another feature that made cracking the Union ciphers much more difficult.

That is our next blog post!