Editing RC5 (section)

==Description==
Unlike many schemes, RC5 has a variable [[block size (cryptography)|block size]] (32, 64 or 128 [[bit]]s), [[key size]] (0 to 2040 bits), and number of rounds (0 to 255). The original suggested choice of parameters were a block size of 64 bits, a 128-bit key, and 12 rounds.

A key feature of RC5 is the use of data-dependent rotations; one of the goals of RC5 was to prompt the study and evaluation of such operations as a [[cryptographic primitive]].{{citation needed|date=November 2016}} RC5 also consists of a number of [[modular arithmetic|modular]] additions and [[XOR|eXclusive OR (XOR)]]s. The general structure of the algorithm is a [[Feistel cipher|Feistel]]-like network, similar to RC2. The encryption and decryption routines can be specified in a few lines of code. The key schedule, however, is more complex, expanding the key using an essentially [[one-way function]] with the binary expansions of both [[e (mathematical constant)|e]] and the [[golden ratio]] as sources of "[[nothing up my sleeve number]]s". The tantalising simplicity of the algorithm together with the novelty of the data-dependent rotations has made RC5 an attractive object of study for cryptanalysts.{{according to whom|date=November 2016}}
RC5 is basically denoted as RC5-w/r/b where w=word size in bits, r=number of rounds, b=number of bytes in the key.