Breaking a Two Hundred Year Old Code

In today's WSJ, Rachel Silverman authored an article title, "Two Centuries On, a Cryptologist Cracks a Presidential Code Unlocking This Cipher Wasn't Self-Evident; Algorithms and Educated Guesses."  A 36 year-old mathmatician breaks this code in a letter written to Thomas Jefferson.

PDF version of letter  (11 MB)

-Chris