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The Rail Fence cipher is a form of transposition cipher that gets its name from the way in which it is encoded. In the rail fence cipher, the plaintext is written downward and diagonally on successive "rails" of an imaginary fence, then moves up when it gets to the bottom. The message is then read off in rows.
The cipher's key is , the number of rails. If N {\displaystyle N} is known, the ciphertext can be decrypted by using the above algorithm. Values of N {\displaystyle N} equal to or greater than L {\displaystyle L} , the length of the ciphertext, are not usable, since then the ciphertext is the same as the plaintext.
In a transposition cipher, the letters themselves are kept unchanged, but their order within the message is scrambled according to some well-defined scheme. Many transposition ciphers are done according to a geometric design. A simple (and once again easy to crack) encryption would be to write every word backwards.
Although ciphers can be confusion-only (substitution cipher, one-time pad) or diffusion-only (transposition cipher), any "reasonable" block cipher uses both confusion and diffusion. [2] These concepts are also important in the design of cryptographic hash functions , and pseudorandom number generators , where decorrelation of the generated ...
The sender chooses a set number of words at random from the poem and gives each letter in the chosen words a number. The numbers are then used as a key for a transposition cipher to conceal the plaintext of the message. The cipher used was often double transposition. To indicate to the receiver which words had been chosen, an indicator group of ...
The first letter of each ciphertext pair is the row, and the second ciphertext letter is the column, of the plaintext letter in the grid (e.g., "AF" means "row A, column F, in the grid"). Next, the fractionated message is subject to a columnar transposition. The message is written in rows under a transposition key (here "CARGO"):
Facsimile of a BATCO cipher sheet. BATCO , short for Battle Code, is a hand-held, paper-based encryption system used at a low, front line (platoon, troop and section) level in the British Army . It was introduced along with the Clansman combat net radio in the early 1980s and was largely obsolete by 2010 due to the wide deployment of the secure ...
A scytale. In cryptography, a scytale (/ ˈ s k ɪ t əl iː /; also transliterated skytale, Ancient Greek: σκυτάλη skutálē "baton, cylinder", also σκύταλον skútalon) is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message.