RC5 is a unique block cipher and it’s first designed by Ronald Rivest in 1994. The RC is a short acronym stands for “Rivest Cipher” or also known as “Ron’s Code!”

RC5 has a variable block size (32, 64 or 128 bits), key size (0 to 2040 bits) and number of rounds (0 to 255). One of the key features of RC5 is the use of data-dependent rotations. The main goal of RC5 was to prompt the study and evaluation of such operations as a cryptographic primitive. RC5 consists of a number of modular additions. The general structure of the algorithm is a Feistel-like network. The enrcytion and decryption routines can also be specified in a few lines of code.

By using this RC5 remote control, you can easily control your TV set. You own build remote control with only one button or even more than hundred buttons! The basic RC5 remote control only have 5 buttons, which as Stand-by, Program + and -, Volume + and -.

If you want more buttons, then you need to write your own routine that read the buttons when they’re connected in a matrix!