Decius Wadsworth
Encyclopedia
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.
Colonel
Colonel , abbreviated Col or COL, is a military rank of a senior commissioned officer. It or a corresponding rank exists in most armies and in many air forces; the naval equivalent rank is generally "Captain". It is also used in some police forces and other paramilitary rank structures...
in the Ordnance Corps
Ordnance Corps
The United States Army Ordnance Corps is a Sustainment branch of the United States Army, headquartered at Fort Lee, Virginia.-Mission Statement:The U.S...
of the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
. In 1817, he developed a progressive cipher system based on a 1790 design by Thomas Jefferson
Thomas Jefferson
Thomas Jefferson was the principal author of the United States Declaration of Independence and the Statute of Virginia for Religious Freedom , the third President of the United States and founder of the University of Virginia...
, establishing a method that was continuously improved upon and used until the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
.
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
Ciphertext
In cryptography, ciphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext that is unreadable by a human or computer without the proper cipher...
. 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
Charles Wheatstone
Sir Charles Wheatstone FRS , was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope , and the Playfair cipher...
invented an almost identical machine several years after Wadsworth, and got all the credit.