Differences between revisions 4 and 5

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($E_{K1}(E_{K2}(P) \neq E_{K3}(P)$)

-  ⇤ ← Revision 4 as of 2005-10-13 21:53:04 → 
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+   ← Revision 5 as of 2005-10-13 21:53:32 → ⇥
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-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($E_{K1}(E_{K2}(P) \neq E_{K3}(P)$)]]
+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($E_{K1}(E_{K2}(P) \neq E_{K3}(P)$)]]