Week 2, Thursday 2.8-2.11

I didn't understand exactly why one-time pads were unbreakable? The book explained that Alice doesn't use the same key twice, but do you use more than one key per plaintext? Also, clarrification of the proof on page 48 would be helpful. Binary and ASCII, both methods of writing numbers, can complicate codes greatly. The problem of true random numbers for key generation is a problem. Computer generated 'random' numbers do not exemplify pure randomness. Cryptographers rely heavily on natural occurances of randomness. Blumb Blum Schub is a practically unpredictable. The linear feedback shift register is very fast and can be easily implemented. The attack is to look for reoccurences and then make some reasonable guesses. Once the length of the reoccurance is determined, all consectuive terms of this sequence length can be determined. Using nonlinear recurrences creates a very complicated, hard to break, code.