RC5 encryption algorithm

RC5 is a block cipher designed by Ronald Rivest. RC stands for "Rivest cipher", alternately "Ron's Code". It has a variable block size (32, 64 or 128 bits), key size (0 to 2040) and number of rounds (0 to 255). RSA security[?] has a patent on the algorithm.

RSA Security offers a series of US$10,000 prizes for breaking a cyphertext encrypted with RC5. Several groups have attempted these challenges using distributed computing, the largest and most successful being Distributed.net[?]. Distributed.net has brute-forced messages encrypted with RC5 in 56 and 64 bit keys, and is currently working on finding a 72 bit key.

External links

• RSA Laboratories FAQ - What are RC5 and RC6? (http://www.rsasecurity.com/rsalabs/faq/3-6-4.html)