Wadsworth's cipher

Wadsworth's cipher was a cipher invented by Decius Wadsworth, a Colonel in the Ordnance Corps of the United States Army. 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.

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. The disks were geared together at a ratio of 26:33. 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. Wadsworth never got credit for his design because Charles Wheatstone invented an almost identical machine several years after Wadsworth, and got all the credit.

References

"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

Cipher machines

Rotor machines	CCM Enigma M-125 Fialka Hebern HX-63 KL-7 Lacida M-325 Mercury NEMA OMI Portex RED SIGABA SIGCUM Singlet Typex

Mechanical	Bazeries cylinder C-36 C-52 CD-57 Cipher disk HC-9 Kryha Jefferson disk M-94 M-209 Reihenschieber Scytale

Teleprinter	5-UCO BID 770 DUDEK KW-26 KW-37 Lorenz SZ 40/42 Siemens and Halske T52

Secure voice	BID 150 FASCINATOR KY-3 KY-57 KY-58 KY-68 NESTOR OMNI SCIP Sectéra Secure Module SIGSALY STE STU-II STU-III VINSON

Other	JADE KG-84 KL-43 KL-51 Noreen PURPLE GREEN（Japanese：-{グリーン暗号}-） Pinwheel Rockex

Cryptography

History of cryptography Cryptanalysis Outline of cryptography

Symmetric-key algorithm Block cipher Stream cipher Public-key cryptography Cryptographic hash function Message authentication code Random numbers Steganography

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