Cryptography Algorithms - Second Edition

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Symmetric Encryption Algorithms

After covering 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 Dive into Cryptography, we saw some symmetric cryptosystems such as ROT13 and the Vernam cipher. Before going further into describing modern symmetric algorithms, we need to overview the construction of the classic 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 ...