K be a set of keys and
M be a set of plaintext messages.
A cipher is a set of encryption functions
a set of decryption functions
for each encryption function
Ee there exists a decryption function
such that for all
(e,d) in the description above is known as a keypair.
L. R. Knudsen, M. J. B. Robshaw, The Block Cipher Companion. Springer, 2011.
Copyright © 2014 Barry Watson. All rights reserved.