Section 3.8 and Sections 2.5-2.8 for September 15

1. (Difficult) I understand how many of the messages are encrypted, but it is the attacks that often do not make complete sense to me. In the ADFGX cipher, I understand how they encode a message, but the attack does not make sense. Similarly, the attack for the block ciphers seem very complicated. I assume that the block cipher attacks are more complicated due to the discussed definitions of diffusion and confusion, where one change in the plain text can alter several letters in the cipher text.

2. (Reflective) I have never found the inverse of a matrix, mod (n), but it makes sense how to find the inverse. I think that algebra, especially matrices, can be very useful in cryptography and that was shown in the block ciphers. Matrices are very useful tools in many areas of mathematics, especially applied mathematics. I did research using matrices, and they are very useful in many areas of mathematics.

I also enjoyed the story about Sherlock Holmes. It was an excellent example of how someone imitate someone else using cryptography.