Original: Note the reversal of the subkey order for decryption; this is the only difference between encryption and decryption: Unbalanced Feistel Cipher Unbalanced Feistel ciphers use a modified structure where and are not of equal lengths.
Simplified: Decryption requires only reversing the order of the subkey using the same process; this is the only difference between encryption and decryption: Unbalanced Feistel ciphers use a modified structure where and are not of equal lengths.