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The Vigenère cipher (French pronunciation: [viʒnɛːʁ]) is a method of encrypting alphabetic text where each letter of the plaintext is encoded with a different Caesar cipher, whose increment is determined by the corresponding letter of another text, the key. For example, if the plaintext is attacking tonight and the key is ...
Kasiski actually used "superimposition" to solve the Vigenère cipher. He started by finding the key length, as above. Then he took multiple copies of the message and laid them one-above-another, each one shifted left by the length of the key. Kasiski then observed that each column was made up of letters encrypted with a single alphabet. His ...
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 ...
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.
Polygraphic substitution cipher: the unit of substitution is a sequence of two or more letters rather than just one (e.g., Playfair cipher) Transposition cipher: the ciphertext is a permutation of the plaintext (e.g., rail fence cipher) Historical ciphers are not generally used as a standalone encryption technique because they are quite easy to ...
A block cipher enciphers input in blocks of plaintext as opposed to individual characters, the input form used by a stream cipher. The Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) are block cipher designs that have been designated cryptography standards by the US government (though DES's designation was finally ...
Bellaso challenged [1] his detractors to solve some cryptograms encrypted according to his guidelines. He also furnished the following clue to help the solution of one of them: ‘‘The cryptogram contains the explanation why two balls, one in iron and one in wood, dropped from a high place will fall on the ground at the same time.’’
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.