2.3 Vigenere Cipher

• Two parts of the reading that I thought were really interesting were that there are books without the letter e. That's pretty amazing. Another interesting part of the reading was how we can use the dot product of vectors in order to determine the length of the shift.
• The hardest part to understand was how we find the length of the key. Not necessarily, how we find the length of the key but rather how that method works. Although it makes sense, I didn't fully (theoretically) understand why there should be more coincidences when you displace the two strips the key length apart.