2/19/2023 0 Comments Transposition cipherThe cipher clerk may also add entire null words, which were often chosen to make the ciphertext humorous. Because this would leave certain highly sensitive words exposed, such words would first be concealed by code. This worked much like an ordinary route cipher, but transposed whole words instead of individual letters. Badly chosen routes will leave excessive chunks of plaintext, or text simply reversed, and this will give cryptanalysts a clue as to the routes.Ī variation of the route cipher was the Union Route Cipher, used by Union forces during the American Civil War. In fact, for messages of reasonable length, the number of possible keys is potentially too great to be enumerated even by modern machinery. Route ciphers have many more keys than a rail fence. The key might specify "spiral inwards, clockwise, starting from the top right". For example, using the same plaintext that we used for rail fence: In a route cipher, the plaintext is first written out in a grid of given dimensions, then read off in a pattern given in the key. In this example, the cylinder is running horizontally and the ribbon is wrapped around vertically. Using the same example as before, if the cylinder has a radius such that only three letters can fit around its circumference, the cipherer writes out: However, the message was easily decrypted when the ribbon recoiled on a cylinder of the same diameter as the encrypting cylinder. The letters of the original message would be rearranged when the ribbon was uncoiled from the cylinder. The message to be encrypted was written on the coiled ribbon. The system consisted of a cylinder and a ribbon that was wrapped around the cylinder. The rail fence cipher follows a pattern similar to that of the scytale, (pronounced "SKIT-uhl-ee") a mechanical system of producing a transposition cipher used by the ancient Greeks. The spacing is not related to spaces in the plaintext and so does not carry any information about the plaintext.) This is a common technique used to make the cipher more easily readable. (The cipher has broken this ciphertext up into blocks of five to help avoid errors. For example, using three "rails" and a message of 'WE ARE DISCOVERED FLEE AT ONCE', the cipherer writes out: In the rail fence cipher, the plaintext is written downwards and diagonally on successive "rails" of an imaginary fence, then moving up when we get to the bottom. The Rail Fence cipher is a form of transposition cipher that gets its name from the way in which it is encoded.
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