One fascinating thing about this section for me was the idea that true randomness essentially only exists in nature. My father works for an electronics company that makes semiconductors so my curiosity was especially piqued when I read that the 'thermal noise from a semiconductor resistor is known to be a good source of randomness' (pg. 41). Computers help with more aspects of cryptography then I ever thought, but they haven't been able to generate true randomness yet.
The hardest part of these sections was the Linear Feedback Shift Register Sequences. I think that the idea is to create a ciphertext out of a one-way function in mod 2, but actually coming up with such a sequence and then decrypting it went over my head. I think that all the x variables are known pieces of the binary ciphertext, but I'm not sure. The matrix in the proposition on page 48 also confused me. This cipher reminds me of the Hill cipher because of the usage of linear algebra, although it appears to be much more complex.
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