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The Zimmermann Telegram (as it was sent from Washington to Mexico) encrypted as ciphertext. KGB ciphertext found in a hollow nickel in Brooklyn in 1953. In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. [1]
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.
This operation is self-inverse, whereby the same table is used for both encryption and decryption. The autokey cipher, which mixes plaintext with a key to avoid periodicity. The running key cipher, where the key is made very long by using a passage from a book or similar text.
With the Caesar cipher, encrypting a text multiple times provides no additional security. This is because two encryptions of, say, shift A and shift B, will be equivalent to a single encryption with shift A + B. In mathematical terms, the set of encryption operations under each possible key forms a group under composition. [26]
Decrypt the second-to-last ciphertext block using ECB mode. C n = C n || Tail (D n, B−M). Pad the ciphertext to the nearest multiple of the block size using the last B−M bits of block cipher decryption of the second-to-last ciphertext block. Swap the last two ciphertext blocks. Decrypt the (modified) ciphertext using the standard CBC mode.
Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often used in military messaging. Since then, new techniques have emerged and become commonplace in all areas of modern computing. [1] Modern encryption schemes use the concepts of public-key [2] and symmetric-key. [1]
The key to decrypt a message requires no more knowledge than the fact that ROT13 is in use. Even if secrecy does not fail, any alien party or individual, capable of intercepting the message, could break the code by spending enough time on decoding the text through frequency analysis [2] or finding other patterns.
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. There are two forms of autokey cipher: key-autokey and text-autokey ciphers.