In the first article in this series on the basics of crypto, “Ease Me Into Cryptography Part 1: Buzzwords and Hash Function“, we learned some lingo and talked about the different aspects of hash functions. Remember that hash functions are one-way — we cannot reverse them algorithmically. We talked about why this is useful, however let’s get to something that we can encrypt AND decrypt. In cryptography, we call these ciphers. Just like in the last section, and in true “Explain Like I’m Five” fashion, let’s break this down. What is a cipher? What are symmetric ciphers? How are they useful? Are there any weaknesses?