Search results
Results from the WOW.Com Content Network
A simple variant is to encrypt by using the Vigenère decryption method and to decrypt by using Vigenère encryption. That method is sometimes referred to as "Variant Beaufort". It is different from the Beaufort cipher, created by Francis Beaufort, which is similar to Vigenère but uses a slightly modified enciphering mechanism and tableau.
Assuming a standard shift of 1 with no key used, the encrypted text HFNOS would be decrypted to HELLO (H->H, F->E, N->L, O->L, S->O ). So, for example, to decrypt the second letter of this text, first find the F within the second interior column, then move directly to the left, all the way to the leftmost header column, to find the ...
Given an individual letter 'E' in a message, it could be encrypted using any of 52 instructions depending on its location and neighbors, which can be used to great advantage to mask the frequency of individual letters. However, the security boost is limited; while it generally requires a larger sample of text to crack, it can still be done by hand.
To decrypt, the process is reversed. Unlike the otherwise very similar Vigenère cipher, the Beaufort cipher is a reciprocal cipher, that is, decryption and encryption algorithms are the same. This obviously reduces errors in handling the table which makes it useful for encrypting larger volumes of messages by hand, for example in the manual ...
An autokey cipher (also known as the autoclave cipher) is a cipher that incorporates the message (the plaintext) into the key. The key is generated from the message in some automated fashion, sometimes by selecting certain letters from the text or, more commonly, by adding a short primer key to the front of the message.
The Alberti cipher by Leon Battista Alberti around 1467 was an early polyalphabetic cipher. Alberti used a mixed alphabet to encrypt a message, but whenever he wanted to, he would switch to a different alphabet, indicating that he had done so by including an uppercase letter or a number in the cryptogram.
The key, which is given as one input to the cipher, defines the mapping between plaintext and ciphertext. If data of arbitrary length is to be encrypted, a simple strategy is to split the data into blocks each matching the cipher's block size, and encrypt each block separately using the same key.
Using the solved message, the analyst can quickly determine what the keyword was. Or, in the process of solving the pieces, the analyst might use guesses about the keyword to assist in breaking the message. Once the interceptor knows the keyword, that knowledge can be used to read other messages that use the same key.