In a 1992 Studies in Intelligence article, "America's First
Encrypted Cable," Ralph Weber refers to a "Monroe cypher:"
http://cryptome.org/us-cable1.htm
We would appreciate information on this cipher, and a
sample of its use with plaintext and ciphertext, or, a long
shot, a source for the whole thing.
This except from David Kahn's "The Codebreakers"
may refer to the cypher:
Another code composed on the Livingston forms, endorsed
"Mr. Monroe's cypher," was used by Monroe in 1805 when
he was minister to England, by James A. Bayard in 1814 when
he helped negotiate the treaty that ended the War of 1812, and
as late as 1832 by President Andrew Jackson in letters to a
diplomatic agent. It therefore seems to have been one of the
first official codes of the United States under the Constitution."
-- p. 185, 1967 edition
