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The cipher illustrated here uses a left shift of 3, so that (for example) each occurrence of E in the plaintext becomes B in the ciphertext. 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.
The shrinking generator uses two linear-feedback shift registers. One, called the A sequence, generates output bits, while the other, called the S sequence, controls their output. Both A and S are clocked; if the S bit is 1, then the A bit is output; if the S bit is 0, the A bit is discarded, nothing is output, and the registers are clocked again.
The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that each letter encrypts to one other letter, and back again, meaning the cipher is essentially a ...
Some ciphers have simple key schedules. For example, the block cipher TEA splits the 128-bit key into four 32-bit pieces and uses them repeatedly in successive rounds. DES has a key schedule in which the 56-bit key is divided into two 28-bit halves; each half is thereafter treated separately.
ROT13 is a simple letter substitution cipher that replaces a letter with the 13th letter after it in the Latin alphabet. ROT13 is a special case of the Caesar cipher which was developed in ancient Rome, used by Julius Caesar in the 1st century BC. [1] An early entry on the Timeline of cryptography.
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. For example, using the same plaintext that we used for rail fence: W R I O R F E O E E E S V E L A N J A D C E D E T C X The key might specify "spiral inwards, clockwise, starting from the top right".
An early substitution cipher was the Caesar cipher, in which each letter in the plaintext was replaced by a letter three positions further down the alphabet. [23] Suetonius reports that Julius Caesar used it with a shift of three to communicate with his generals. Atbash is an example of an early Hebrew cipher.
For example, in a Caesar cipher of shift 3, a would become D, b would become E, y would become B and so on. The Vigenère cipher has several Caesar ciphers in sequence with different shift values. To encrypt, a table of alphabets can be used, termed a tabula recta, Vigenère square or Vigenère table. It has the alphabet written out 26 times in ...