Outline for November 6, 2006
Greetings and felicitations!
Quick review for midterm
Cryptanalysis: first do index of coincidence to see if it is monoalphabetic or polyalphabetic, then Kasiski method.
Problem: eliminate periodicity of key
Long key generation
= MOILVGOFXTMXZFLZAEQ; wedge is that (plaintext, key) letter pairs are not random (T/T, H/H, E/E, T/S, R/E, A/O, S/N, etc.)
Perfect secrecy: when the probability of computing the plaintext message is the same whether or not you have the ciphertext
Only cipher with perfect secrecy: one-time pads;
= AZPR; is that DOIT or DONT?
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Version of November 5, 2006 at 5:54 PM