Before this course, when I thought of cryptography I primarily thought of advanced groups and organizations who made unbreakable codes so that nobody else would ever know the information they were communicating except for the people they were communicating to. However, this is definitely not the entire story. First, most everyone in society uses cryptography in some way in their lives. A lot of the time people aren't even aware that they are utilizing cryptography, primarily when they are online. I was previously unaware of how much cryptography was involved in things online such as passwords and other sensitive information. I'm glad though that online passwords and other information gets encrypted before it is sent as if it weren't then it would be extremely easy for anyone to get your sensitive information.
Now the other main thing which my eyes were opened to was the potential weakness in encryption. Before I thought that for the most part, codes weren't ever cracked or figured out by people other than those that the messages are to. The story of Queen Mary taught me otherwise. While there are over 4*10^26 different ways to encrypt using a basic substitution cipher, it is not always that difficult to figure out the encryption methods. Cryptanalysis and its methods are new topics to me, but when thinking about them, I had even used some of them in the past (primarily frequency analysis). The main point however is that any encryption method can be figured out and thus no method of encryption is 100% secure. Other weaknesses include that you can't make an encryption method so complex that your recipient cannot understand the message, and it isn't necessarily possible to tell if someone else has figured out your encryption method. Particularly the latter is a major weakness as one's method of encryption can in fact be used against them and this was an interesting possibility which had never occurred to me before. Cryptography can be extremely useful and has its advantages, but it is not without disadvantages either.