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A disk cipher device of the Jefferson type from the 2nd quarter of the 19th century in the National Cryptologic Museum. The Jefferson disk, also called the Bazeries cylinder or wheel cypher, [1] was a cipher system commonly attributed to Thomas Jefferson that uses a set of wheels or disks, each with letters of the alphabet arranged around their edge in an order, which is different for each ...
In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code, or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet.
The tap code is based on a Polybius square using a 5×5 grid of letters representing all the letters of the Latin alphabet, except for K, which is represented by C. . Each letter is communicated by tapping two numbers, the first designating the row and the second (after a pause) designating the column.
A generalisation of the Lehmer generator and historically the most influential and studied generator. Lagged Fibonacci generator (LFG) 1958 G. J. Mitchell and D. P. Moore [5] Linear-feedback shift register (LFSR) 1965 R. C. Tausworthe [6] A hugely influential design. Also called Tausworthe generators. Wichmann–Hill generator: 1982
The two letters of the digram are considered opposite corners of a rectangle in the key table. To perform the substitution, apply the following 4 rules, in order, to each pair of letters in the plaintext: If both letters are the same (or only one letter is left), add an "X" after the first letter. Encrypt the new pair and continue.
However, the need in a Fisher–Yates shuffle to generate random numbers in every range from 0–1 to 0–n almost guarantees that some of these ranges will not evenly divide the natural range of the random number generator. Thus, the remainders will not always be evenly distributed and, worse yet, the bias will be systematically in favor of ...
Then each letter of the false message must be presented in the appropriate typeface, according to whether it stands for an A or a B. [4] To decode the message, the reverse method is applied. Each "typeface 1" letter in the false message is replaced with an A and each "typeface 2" letter is replaced with a B. The Baconian alphabet is then used ...
ROT13 and ROT5 can be used together in the same message, sometimes called ROT18 (18 = 13 + 5) or ROT13.5. ROT47 is a derivative of ROT13 which, in addition to scrambling the basic letters, treats numbers and common symbols.