"Pers Z S" code-breaking group of the German Foreign Office cracked the M-138-A in 1944. However, by that time the Americans had more sophisticated cipher systems in operation. The French cryptographer Gaetan de Viaris (aka Marquis Gaetan Henri Leon Viarizio di Lesegno) who is famous for one of the first printing cipher devices (1874), solved the Bazeries cylinder in 1893. One major weakness of the Bazeries cylinder is that the offset from the plaintext letter to the ciphertext letter for the cipher alphabet on each disk will be exactly the same. In the example shown above, this offset is six letters. For example, if a cryptanalyst has captured the ten disk Bazeries cylinder described in the example above, this should not be enough to permit them to decipher messages with it, since they also have to know the key, or the arrangement of the disks on the cylinder. The number of possible permutations of the disks of the example Bazeries cylinder is: Due to the large size of this number, trial and error testing of the arrangement of the disks difficult to perform by hand. Sources The Codebreakers, David Kahn, 1967, pp. 192–195 "Monticello." Wheel Cipher. Accessed April 8, 2022. https://www.monticello.org/site/research-and-collections/wheel-cipher. Riverbank Publication Number 20, Several Machine Ciphers and Methods for their Solution, William F. Friedman, 1918, in Methods for the Solution of Ciphers, Publications 15-22, Rufus A. Long Digital Library of Cryptography, George C. Marshall Library, 1917-1922, "Rossignols." Wikipedia. Wikimedia Foundation, November 19, 2021. https://en.wikipedia.org/wiki/Rossignols. External links Thomas Jefferson's Wheel Cipher American inventions Encryption devices Thomas Jefferson