The article talks about Feistel networks and the most famous Feistel cipher, DES. I wrote a spreadsheet where you can examine every bit of the computation of DE

The article talks about Feistel networks and the most famous Feistel cipher, DES. I wrote a spreadsheet where you can examine every bit of the computation of DES encryption: https://www.nayuki.io/page/des-cipher-internals-in-excel https://www.nayuki.io/page/des-cipher-internals-in-excel