Here is a book that if you study and work through the examples therein, it will help prepare you for the coming cryptanalysis of Rijndael (pronounced Rhine-dael). It is termed a block cipher because it encrypts a file or message by encrypting each successive 128 bits.

Mathematics becomes like art when there is no known solution for a problem.

Please ignore the shilling picking up as I continue this walkthrough, for those who are reading. They don't want you to take a deeper look at what we consider "secure."

We will also need to go over matrices. There is a good course on Khan Academy which explains the conventions for matrix arithmetic. As you will see, AES is all about matrices, which are represented by arrays.

Adding and Subtracting Matrices

https://www.youtube.com/watch?v=QXUbFzEd3Ww

❤² Matrix Multiplication.. How? (mathbff)

https://www.youtube.com/watch?v=T1h71v-u3SQ

Consuming this series will help, since a lot of cryptanalysis will be linear algebra.

https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2xVFitgF8hE_ab