Chapter 2: Introduction to Symmetric Encryption
After having an overview of cryptography, it's time now to present the principal algorithms in symmetric encryption and their logic and mathematical principles.
In Chapter 1, Deep Diving into Cryptography, we saw some symmetric cryptosystems such as ROT13 and the Vernam cipher. Before going further into describing modern symmetric algorithms, we need an overview of the construction of block ciphers.
If you recall, symmetric encryption is performed through a key that is shared between the sender and receiver and vice versa. But how do we implement symmetric algorithms that are robust (in the sense of security) and easy to perform (computationally) at the same time? Let's see how we can answer this question by comparing asymmetric with symmetric encryption.
One of the main problems with asymmetric encryption is that it is not easy to perform the operations (especially the decryption), due to the high capacity of computation...
