Direct Connect++ $Lock to $Key conversion class (Java)

DCConvert.java

class DCConvert {
    private String retKey;
    private int len;
    private static boolean DEBUG = false;

    public DCConvert(String s) {
        char[] lock = s.toCharArray();
        len = lock.length;
        char[] key = new char[len];
        for (int i = 0; i < s.length(); i++) {
            if (i == 0)
                key[i] = (char) ((int) lock[0] ^ (int) lock[len - 1] ^ (int) lock[len - 2] ^ 5);
            else
                key[i] = (char) ((int) lock[i] ^ (int) lock[i - 1]);
            if (DEBUG)
                System.out.println(lock[i] + " = " +
                        Integer.toBinaryString((int) lock[i] & 0xffffff) +
                        "\tkey[" + i + "] = " +
                        Integer.toBinaryString((int) key[i] & 0xffffff));
        }
        key = convertLocktoKey(lock, key);
        retKey = makeRetKey(key);
    }

    private char[] convertLocktoKey(char[] lock, char[] key) {
        // Next, every character in the key must be nibble-swapped:
        //     for (i = 0; i < len; i++)
        //         key[i] = ((key[i]<<4) & 240) | ((key[i]>>4) & 15)
        if (DEBUG)
            System.out.println("Ultima modificaçao...");

        for (int i = 0; i < len; i++) {
            key[i] = (char) ((((int) key[i] << 4) & 0xf0) | (((int) key[i] >> 4) & 0xf));

            if (DEBUG)
                System.out.println("key[" + i + "]: " + key[i] + "");
        }

        return key;
    }

    private String makeRetKey(char[] key) {
        String charA = "\\x00";    // ASCII 0   -> Hex 00
        String charB = "\\x05";    // ASCII 5   -> Hex 00
        String charC = "\\x24";    // ASCII 36  -> Hex 00
        String charD = "\\x60";    // ASCII 96  -> Hex 60 -> `
        String charE = "\\x7C";    // ASCII 124 -> Hex 7C
        String charF = "\\x7E";    // ASCII 126 -> Hex 7E -> ~
        String retKey = new String(key);

        // Finally, the characters with the decimal ASCII values of
        // 0, 5, 36, 96, 124, and 126 cannot be sent to the server.
        // Each character with this value must be substituted with the string
        // /%DCN000%/, /%DCN005%/, /%DCN036%/, /%DCN096%/, /%DCN124%/,
        // or /%DCN126%/, respectively.
        // The resulting string is the key to be sent to the server.
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 0 ('" + charA + "')");
        retKey = retKey.replaceAll(charA, "/%DCN000%/");
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 5 ('" + charB + "')");
        retKey = retKey.replaceAll(charB, "/%DCN005%/");
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 36 ('" + charC + "')");
        retKey = retKey.replaceAll(charC, "/%DCN036%/");
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 96 ('" + charD + "')");
        retKey = retKey.replaceAll(charD, "/%DCN096%/");
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 124 ('" + charE + "')");
        retKey = retKey.replaceAll(charE, "/%DCN124%/");
        if (DEBUG)
            System.out.println(retKey + "\nSubstituir ACSCII 126 ('" + charF + "')");
        retKey = retKey.replaceAll(charF, "/%DCN126%/");

        return retKey;
    }

    /**
     * returns the key
     */
    public String getKey() {
        return retKey;
    }
}