DES - Part 3 - The Feistel Function of the Data Encryption Standard

In this video we briefly review what a Feistel function of a general Feistel cipher is and then discuss the definition and the implementation of the Feistel function for the Data Encryption Standard (DES).

Code for video:

Example:

[Jim-vrlx]

Using the pBox function for the key rotation was very smart. I’ve read many implementations of DES and have never seen that done before. It makes the code much easier to read & follow. As a matter of fact, after coding your examples in c, for the first time, I realized that there are no arithmetic operations underpinning DES – just substitutions. There are no groups, rings, fields, or vector spaces (linear or affine) with mixed operations to worry about. Yes, the RoundKey is Xor’d with half the block, but this doesn't seem exploitable in an abstract algebra sorta way. All security in DES rests in those s-boxes. I can see that better now. Please keep up the great work. P.S. If I’m wrong, please let me know.

[shanereilly]

This is a fantastic channel! I really enjoy your content. I'm completely bewildered as to how you don't have more subscribers.

[AdiSings]

Any chance to get the last part? Awesome content btw

[UniverseGames]

Very informative. Do you have any plan for making some videos related to Quantum Cryptography or research paper related videos and their explanation-maths and codes