RC4

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RC4

(cryptography)
A cipher designed by RSA Data Security, Inc. which can accept keys of arbitrary length, and is essentially a pseudo random number generator with the output of the generator being XORed with the data stream to produce the encrypted data. For this reason, it is very important that the same RC4 key never be used to encrypt two different data streams. The encryption mechanism used to be a trade secret, until someone posted source code for an algorithm onto Usenet News, claiming it to be equivalent to RC4. The algorithm is very fast, its security is unknown, but breaking it does not seem trivial either. There is very strong evidence that the posted algorithm is indeed equivalent to RC4.

The United States government routinely approves RC4 with 40-bit keys for export. Keys this small can be easily broken by governments, criminals, and amateurs. The exportable version of Netscape's Secure Socket Layer, which uses RC4-40, was broken by at least two independent groups. Breaking it took about eight days; in many universities or companies the same computing power is available to any computer science student.

See also Damien Doligez's SSL cracking page, RC4 Source and Information, SSLeay, Crypto++, Ssh, A collection of articles.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

RC algorithms

(Ron's Code or Rivest's Cipher algorithms) A family of secret-key cryptographic algorithms from RSA Security, Inc., Bedford, MA (www.rsa.com). Although RSA (formerly RSA Data Security and acquired by EMC in 2006) is widely known for its public key methods, its secret key algorithms are also widely used. Ronald Rivest is the "R" in RSA.

Designed as a replacement for DES, RC2 uses a variable key and the block cipher method. RC4 uses a variable key and stream cipher method. Both RC5 and RC6 are block ciphers with variable keys up to 2,040 bits. RC6, designed by Rivest and others, uses integer multiplication for improved performance. RC6 was created to conform to the AES standard and was a finalist in the competition for the AES algorithm. See RSA, EMC, AES and DES.
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References in periodicals archive ?
DH-9800 supports analog scrambling, and digital encryption using Advanced Encryption Standard (AES) and ARCFOUR (ARC4) encryption algorithm to voice with 256-bit encryption.