Pretty Good Privecy (PGP) is a well known security system used by computer enthusiasts to encrypt their email; it is an example of a practical hybrid encryption system which uses both secret key and public key [4]. At all Initially, this array is set to the identity permutation (see pseudo-code below). secret key systems. The key stream is completely independent of the plaintext used. In the open literatures, there is very small number of proposed keystream generator that are not based on shift registers. a) True The same algorithm is used for both encryption and decryption as the data stream is simply XORed with the generated key sequence. RC4 algorithm has a variable length of key between (0-255) bytes to initialize the 256 bytes in the initial state array (State [0] to State [255]) [13]. A variable-length key from 1 to 256 bytes (8 to 2048 bits) is used to initialize a 256-byte state vector S, with elements S[0], S[1], …, S[255]. Answer: d Explanation: In September 1994, the RC4 algorithm was anonymously posted on the Internet on the Cypherpunks anonymous remailers list. Among numerous applications it is used to protect Internet traffic as part of the SSL andis integratedinto MicrosoftWindows. On September 9, 1994, the RC4 algorithm was anonymously posted on the Internet on the Cyperpunks’ “anonymous remailers” list. An RC4 ALGORITHM RC4 is a stream cipher, symmetric key algorithm. The concept of RC4 is to make a permutation of the elements by swapping them to accomplish the higher randomness. The RC4 algorithm is remarkably simple and quite easy to explain, shown in figure 3. 3.6 Twofish Twofish [19] is an algorithm … The algorithms below show KSA and PRGA steps of the RC4 algorithm: Algorithm 1. Keywords: cryptanalysis, stream cipher, RC4 1 Introduction RC4 is probably the most popular stream cipher that do not base on a feedback shift register. RC4 has a secret … It was developed in 1987 by Ronald Rivest and kept as a trade secret by RSA Data Security. 1 Introduction RC4 was designed by Ron Rivest in 1987 and kept as a trade secret until it leaked in 1994. RC4 was kept as a trade secret by RSA Security. The same algorithm is used for both RC4 is a widely used stream cipher whose algorithm is very simple. advertisement. oIt was developed in 1987 by Ron Rivest, but the algorithm was kept secret until 1994. oAfter this publication several weaknesses were discovered in the pseudo random sequence generated by RC4. 12. Keywords: RC4, stream ciphers, random shuffle, keystream generator. It was developed in 1987 by Ron Rivest, but the algorithm was kept secret until 1994. The RC4 was proposed by Ron Rivest in 1987 for RSA Data Security and was kept as trade secret till 1994 when it was leaked out [4]. The algorithm can be efficiently implemented in both hardware and software. Ø The main idea is that RC4 is commonly used with keys of the form : … RC4, a fast output-feedback cipher, is one of the most widely used cryptosystems on the Internet, commonly used as the default cipher for SSL/TLS connections [20]. RC4 creates a finite-state machine that uses a state array of 256 bytes. It has withstood the test of time in spite of its simplicity. It was designed by Ron Rivest in 1987 for RSA Data Security, Inc., and kept as a trade secret until it leaked out in 1994 and is now RC4, also known as ARC4 , was kept as a trade secret until 1994, when it was posted anonymously to the cypherpunks mailing list. RC4 ALGORITHM RC4 is a stream cipher, symmetric key algorithm. It was designedby RonRivest in 1987 and kept as a trade secret until it leaked out in 1994. Today RC4 is a part of many network protocols, e.g. One of the algorithms I frequently use is the RC4. software.RC4 was kept as a trade secret by RSA Security. 4. 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