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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 is known, the ciphertext can be decrypted by using the above algorithm. Values of equal to or greater than , the length of the ciphertext, are not usable, since then the ciphertext is the same as the plaintext. Therefore the number of usable keys is low, allowing the brute-force attack of trying all ...
The resulting message, 3113212731223655 has to be secured by other means if the straddling checkerboard table is not scrambled. By passing digits through an additional transposition or substitution cipher stage can be used to secure message -- to whatever extent transposition or substitution can be considered secure.
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 ...
Let's encrypt the word "SOMETEXT" with a Caesar cipher using a shift equal to the side of our square (5). To do it, locate the letter of the text and insert the one immediately below it in the same column for the ciphertext. If the letter is in the bottom row, take the one from the top of the same column.
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.
The Rijndael S-box can be replaced in the Rijndael cipher, [1] which defeats the suspicion of a backdoor built into the cipher that exploits a static S-box. The authors claim that the Rijndael cipher structure is likely to provide enough resistance against differential and linear cryptanalysis even if an S-box with "average" correlation ...
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"):