Method subBytes

src/main/java/com/thealgorithms/ciphers/AES.java:2539–2547

substitutes 8-Bit long substrings of the input using the S-Box and returns the result. @return subtraction Output

(BigInteger ciphertext)

     * @return subtraction Output
     */
    public static BigInteger subBytes(BigInteger ciphertext) {
        int[] cells = splitBlockIntoCells(ciphertext);

        for (int i = 0; i < 16; i++) {
            cells[i] = SBOX[cells[i]];
        }

        return mergeCellsIntoBlock(cells);
    }

    /**
     * substitutes 8-Bit long substrings of the input using the inverse S-Box