Feistel function

A Feistel function is a core part of many encryption algorithms that helps secure data. It takes a piece of data, called a block, and splits it into two halves. One half is processed through a complex function involving mixing and permutations, then combined with the other half. This process is repeated multiple times with different keys to transform the data into an encrypted form. The Feistel structure ensures that the encryption and decryption processes are similar, making the system both secure and efficient, and allowing data to be securely scrambled and unscrambled using the same method.