Symmetric Block Ciphers
Triple DES
First some stats to think about:
Single DES uses a 56 bit key. So the number of keys is 2^56.
The number of bits in a block is 64 so any block can be mapped to one of 2^64 different blocks.
It seems reasonable then that DES using key K1 has a range of X and using key K2 has a range of Y where X and Y are different and the symmetric difference is non-empty (latex2($\left( X \bigtriangleup Y \neq \emptyset \right)$). This is actually true so that latex2($E_{K1}(E_{K2}(P) \neq E_{K3}(P)$)
Blowfish
RC5
Characteristics of Advanced Symmetric Block Ciphers
RC4 Stream Cipher
Review Questions