The Use of Ciphers in Colonial America

  Whenever I discuss Dr Benjamin Church Jr with someone not familiar with him and I mention the fact that he was arrested after attempting to smuggle a cipher letter to his brother-in-law in British occupied Boston, invariably I get a reaction that indicates that Dr Church must have been up to something no good if he sent a letter that was encrypted. I think a discussion of the use of ciphers in letters in Colonial America would be of benefit.

  The first recorded use of a cipher in communications in the Western World is that of one used by Gaius Julius Caesar to communicate with his generals. According to Suetonius, Caesar used a simple substitution code by changing the letters of the alphabet. In one code he just substituted the fourth letter down from the letter he wished to; thus D was substituted for A, and so forth. This code is easily broken by a knowledgeable cryptologist but may have been made more difficult in Caesar's day since letters were written without any space between words as is now done. In fact, Caesar was admired for his ability to look at a manuscript and quickly make out the specific words in what would have been a continuous line of letters. Another Roman historian believes that Caesar used several more sophisticated codes. In any event, the use of ciphers has a long history in the Western World.

Note how this inscription from the Colosseum has no spacing.

  Secret communication methods were widely used in Seventeenth and Eighteenth Century England. When  the legendary David Shulman published his  An Annotated Bibliography of Cryptography, in 1976,  he listed a number of treatises on cryptographic subjects published in England between 1593 and 1776, as well as scholarly books that contained chapters on use of codes, ciphers, and secret writing techniques. In 1641, John Wilkins, Bishop of Chester and Oliver Cromwell's brother-in-law, published Mercury, or the Secret and Swift Messenger, a treatise that illustrates  the widespread knowledge of various techniques for concealment of a message. Wilkins described the use of parables of scripture, inversion of known words, secret inks and papers, changing the place of common letters, use of keys, double alphabets, invented characters, emblems, hieroglyphics, the use of tones and musical notes, as well as fire and smoke signals.

  The printing press brought about the publication of a large number of treatises on encryption and closely related subjects. According to one major history of cryptography, a number of prominent figures in British history used ciphers. They included Roger Bacon, Geoffrey Chaucer, and Mary Queen of Scots. The House of Lords was sufficiently familiar with ciphers that it allowed the introduction of deciphered writings in the 1723 trial of Bishop Francis Atterbury and the Royal Mail was so familiar with private and diplomatic ciphers that, by 1720 in London, it operated one of the most sophisticated overnight systems of opening and deciphering mail.

   In Colonial America, secret communications were used to defeat the efforts of government agents and social censors. Before 1700, John and Mary Winthrop of Puritan Massachusetts corresponded in a private cipher regarding intimate matters, thus concealing their affairs from persons who might read their messages while in the process of transmission by hand.

   Because of the government practice of opening and reading private mail, and because mail might be stolen from the post riders, there was a substantial risk of exposure in colonial America.  

   In 1764, a young Thomas Jefferson suggested to John Page the use of a hundred-year-old English text (Shelton’s Tachygraphia ) to encode their letters to protect information about Jefferson’s unsuccessful efforts to court a young lady.

I wish I had followed your example, and wrote it in Latin, and that I had called my dear campana in die instead of αδνιλεβ. We must fall on some scheme of communicating our thoughts to each other, which shall be totally unintelligible to every one but to ourselves. I will send you some of these days Shelton’s Tachygraphical Alphabet, and directions.

                                   Jefferson to John Page, 23 January 1764

   When Jefferson sent Lewis and Clark on their famous expedition, he instructed them to:

   Avail yourself of these means to communicate to us, at seasonable intervals, a copy of your journal, notes & observations, of every kind, putting into cypher whatever might do injury if betrayed.

                                             Jefferson to Lewis, 20 June 1803

   In 1795 Jefferson invented his "wheel cypher" - a cypher system using a set of wheels or disks, each with the 26 letters of the alphabet arranged around their edge. The order of the letters is different for each disk and is usually scrambled in some random way. Each disk is marked with a unique number. A hole in the centre of the disks allows them to be stacked on an axle.The disks are removable and can be mounted on the axle in any order desired. The order of the disks is the cipher key, and both sender and receiver must arrange the disks in the same predefined order. Jefferson's device had 36 disks.  

Jefferson's "wheel cypher."

 John Adams used a cipher provided by his friend James Lovell to communicate non-governmental and private information to his wife Abigail. Lovell also provided Benjamin Franklin and Horatio Gates with a cipher for use in their private correspondence in the late 1780s and 1790s.

   Among the Revolutionary War figures known to use ciphers in their private correspondence were James Madison, James Monroe, Alexander Hamilton, and Aaron Burr.

Cryptology was not some exotic science in the 1770s in Pre-Revolutionary America and someone as talented as Dr Samuel West, Dr Church's classmate at Harvard, would have had little difficulty in dealing with it. Some of the shock expressed at the time over the cipher was rather disingenuous and, I feel, had to do more with self-preservation. A rebellion against a British Monarch was a very serious business, indeed.