Wadsworth's cipher
Wadsworth's cipher, or Wheatstone's cipher, was a cipher invented by Decius Wadsworth, a Colonel in the United States Army Ordnance Corps.[1] In 1817, he developed a progressive cipher system based on a 1790 design by Thomas Jefferson, establishing a method that was continuously improved upon and used until the end of World War II.[1]
Wadsworth's system involved a set of two disks, one inside the other, where the outer disk had the 26 letters of the alphabet and the numbers 2-8, and the inner disk had only the 26 letters.[1] The disks were geared together at a ratio of 26:33.[1] To encipher a message, the inner disk was turned until the desired letter was at the top position, with the number of turns required for the result transmitted as ciphertext. Due to the gearing, a ciphertext substitution for a character did not repeat until all 33 characters for the plaintext letter had been used.[1] A similar device was invented by Charles Wheatstone several years after Wadsworth.[1]
References
- ^ a b c d e f Kruh, Louis (1982). "THE MYSTERY OF COLONEL DECIUS WADSWORTH'S CIPHER DEVICE". Cryptologia. 6 (3). doi:10.1080/0161-118291857037.
External links
- "A Short History of Cryptography", Fred Cohen, 1995
- "Cryptography Primer", Jose Mari Reyes, 2001
- "Cryptography Timeline", Carl Ellison, December 11, 2004
- Codes, Richard A. Mollin, 2005
