The round function in Serpent consists of key-mixing XOR , thirty-two parallel applications of the same NUMBER@1 S-box , and a linear transformation , except in the last round , wherein another key-mixing XOR replaces the linear transformation .

The round function in Serpent consists of : key-mixing XOR , thirty-two parallel process of the same NUMBER@1 S-box , and a linear transformation , except in the last round , in which another key-mixing XOR replaces the linear transformation .
