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Py (cipher)
Py is a stream cipher submitted to eSTREAM by Eli Biham and Jennifer Seberry. It is one of the fastest eSTREAM candidates at around 2.6 cycles per byte on some platforms. It has a structure a little like RC4, but adds an array of 260 32-bit words which are indexed using a permutation of bytes, and produces 64 bits in each round. The authors assert that the name be pronounced "Roo", a reference to the cipher's Australian origin, by reading the letters "Py" as Cyrillic (Ру) rather than Latin characters. This somewhat perverse pronunciation is understood to be their answer, in jest, to the difficult-to-pronounce name ''Rijndael'' for the cipher which was adopted as the Advanced Encryption Standard. * The original April 2005 proposal included the cipher Py, and a simplified version Py6. The latter reduces the size of some internal tables, providing greatly reduced key scheduling cost, at the expense of a shorter maximum output length. * In June 2006, the authors described Pypy ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Stream Cipher
stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream ( keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the ciphertext stream. Since encryption of each digit is dependent on the current state of the cipher, it is also known as ''state cipher''. In practice, a digit is typically a bit and the combining operation is an exclusive-or (XOR). The pseudorandom keystream is typically generated serially from a random seed value using digital shift registers. The seed value serves as the cryptographic key for decrypting the ciphertext stream. Stream ciphers represent a different approach to symmetric encryption from block ciphers. Block ciphers operate on large blocks of digits with a fixed, unvarying transformation. This distinction is not always clear-cut: in some modes of operation, a block cipher primitive is used in such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
