a Basic substitution-Permutation Network Cipher The cipher that we shall use to present the concepts is a basic Substitution-Permutation Network(SPN) cach round consists of (1)substitution, (2 )a transposition of the bits(i.e, permutation of the bit positions ) and 3 )key mixing This basic structure was presented by Feistel back in 1973 and these basic operations are similar to what is found in des and many other modern ciphers, including rijndael 1616 A Basic Substitution-Permutation Network Cipher • The cipher that we shall use to present the concepts is a basic Substitution-Permutation Network (SPN). • Each round consists of (1) substitution, (2) a transposition of the bits (i.e., permutation of the bit positions), and (3) key mixing. • This basic structure was presented by Feistel back in 1973 and these basic operations are similar to what is found in DES and many other modern ciphers, including Rijndael