Question

The standard/nominal version of the RC5-w/r/b has parameters w/r/b as

(a) 32/18/16

(b) 16/18/16

(c) 32/12/16

(d) 32/16/18

This question was posed to me in quiz.

I'm obligated to ask this question of RC4 and RC5 in section Pseudorandom Number Generation and Stream Ciphers and More Block Ciphers of Cryptograph & Network Security

Answer 1

Right answer is (c) 32/12/16

Easiest explanation: Nominal/Standard version is RC5-32/12/16.

 -i.e. 32-bit words, so encrypts 64-bit data blocks

 -using 12 rounds

 -with 16 bytes (128-bit) secret key.