Search results
Results from the WOW.Com Content Network
A plain language (or code) passage of any length, usually obtained by solving one or more cipher or code messages, and occurring or believed likely to occur in a different cipher or code message, which it may provide a means of solving.
Cipher-block chaining (CBC) mode is an example of block cipher mode of operation. Some block cipher modes (CBC and PCBC essentially) for symmetric-key encryption algorithms require plain text input that is a multiple of the block size, so messages may have to be padded to bring them to this length.
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. The message is then read off in rows.
The adversary receives the encryption of m b, and attempts to "guess" which plaintext it received, and outputs a bit b'. A cipher has indistinguishable encryptions under a chosen-plaintext attack if after running the above experiment the adversary can't guess correctly (b=b') with probability non-negligibly better than 1/2. [3]
Decryption is similar: the decryption algorithm takes, in this example, a 128-bit block of ciphertext together with the secret key, and yields the original 128-bit block of plain text. [ 4 ] For each key K , E K is a permutation (a bijective mapping) over the set of input blocks.
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 ...
Stream ciphers, where plaintext bits are combined with a cipher bit stream by an exclusive-or operation (), can be very secure if used properly. [citation needed] However, they are vulnerable to attacks if certain precautions are not followed: