Method decrypt

src/main/java/com/thealgorithms/ciphers/DES.java:231–249

@param message The encrypted string. Expects it to be a multiple of 64 bits, in binary format @return The decrypted String, in plain English

(String message)

     * @return The decrypted String, in plain English
     */
    public String decrypt(String message) {
        StringBuilder decryptedMessage = new StringBuilder();
        int l = message.length();
        int i;
        int j;
        if (l % 64 != 0) {
            throw new IllegalArgumentException("Encrypted message should be a multiple of 64 characters in length");
        }
        for (i = 0; i < l; i += 64) {
            String block = message.substring(i, i + 64);
            String result = decryptBlock(block, subKeys);
            byte[] res = new byte[8];
            for (j = 0; j < 64; j += 8) {
                res[j / 8] = (byte) Integer.parseInt(result.substring(j, j + 8), 2);
            }
            decryptedMessage.append(new String(res));
        }
        return decryptedMessage.toString().replace("\0", ""); // Get rid of the null bytes used for padding
    }
}