2.1-2.2 and 2.4, due on September 10

1. (Difficult) In Section 2.4, when the book discusses substitution ciphers, it was a little confusing how they deducted the letters from the table. It took a little while to understand how one frequency of two successive letters, led to deducing another letter. The explanation was clear, but it just shows how tedious it can be to decipher the ciphertext would be. The affine ciphers were also more challenging than a simple shift cipher. The modular arithmetic would be more challenging using an affine cipher.

2. (Reflective) Although it was difficult to follow sometimes, I think it is cool that we are able to often decipher a substitution cipher by using the frequency of letters. It is interesting that we have the statistics on the frequency of letters in the English language, but it does make it easier and possibly to break the code. Like I mentioned in the difficulty section, the reasoning takes a little time to understand how one letter can deduce another letter, but it is very interesting. A long line of ciphertext can look intimidating, but using the frequency of letters, we can often figure it out without using any computer at all.