(Rivest Cipher 5) A cipher that encrypts a block (many bytes) of data at a time. The RC5 algorithm enables the user to specify block size, key length, and how many times the encrypted message should be re-encrypted (referred to as encryption rounds).
RC5 is a block cipher notable for its simplicity. Designed by Ronald Rivest in 1994, RC stands for "Rivest Cipher", or alternatively, "Ron's Code" (compare RC2 and RC4). The Advanced Encryption Standard (AES) candidate RC6 was based on RC5.