Idea 12 & 13 Registration Code Generator

import java.math.BigInteger;import java.util.Date;import java.util.Random;import java.util.zip.CRC32;public class keygen{    /**     * @param s     * @param i     * @param bytes     * @return     */    public static short getCRC(String s, int i, byte bytes[])    {        CRC32 crc32 = new CRC32();        if (s != null)        {            for (int j = 0; j < s.length(); j++)            {                char c = s.charAt(j);                crc32.update(c);            }        }        crc32.update(i);        crc32.update(i >> 8);        crc32.update(i >> 16);        crc32.update(i >> 24);        for (int k = 0; k < bytes.length - 2; k++)        {            byte byte0 = bytes[k];            crc32.update(byte0);        }        return (short) (int) crc32.getValue();    }    /**     * @param biginteger     * @return String     */    public static String encodeGroups(BigInteger biginteger)    {        BigInteger beginner1 = BigInteger.valueOf(0x39aa400L);        StringBuilder sb = new StringBuilder();        for (int i = 0; biginteger.compareTo(BigInteger.ZERO) != 0; i++)        {            int j = biginteger.mod(beginner1).intValue();            String s1 = encodeGroup(j);            if (i > 0)            {                sb.append("-");            }            sb.append(s1);            biginteger = biginteger.divide(beginner1);        }        return sb.toString();    }    /**     * @param i     * @return     */    public static String encodeGroup(int i)    {        StringBuilder sb = new StringBuilder();        for (int j = 0; j < 5; j++)        {            int k = i % 36;            char c;            if (k < 10)            {                c = (char) (48 + k);            }            else            {                c = (char) ((65 + k) - 10);            }            sb.append(c);            i /= 36;        }        return sb.toString();    }    /**     * @param name     * @param days     * @param id     * @return     */    public static String MakeKey(String name, int days, int id)    {        id %= 100000;        byte bkey[] = new byte[12];        bkey[0] = (byte) 1; // Product type: IntelliJ IDEA is 1        bkey[1] = 13; // version        Date d = new Date();        long ld = (d.getTime() >> 16);        bkey[2] = (byte) (ld & 255);        bkey[3] = (byte) ((ld >> 8) & 255);        bkey[4] = (byte) ((ld >> 16) & 255);        bkey[5] = (byte) ((ld >> 24) & 255);        days &= 0xffff;        bkey[6] = (byte) (days & 255);        bkey[7] = (byte) ((days >> 8) & 255);        bkey[8] = 105;        bkey[9] = -59;        bkey[10] = 0;        bkey[11] = 0;        int w = getCRC(name, id % 100000, bkey);        bkey[10] = (byte) (w & 255);        bkey[11] = (byte) ((w >> 8) & 255);        BigInteger pow = new BigInteger("89126272330128007543578052027888001981", 10);        BigInteger mod = new BigInteger("86f71688cdd2612ca117d1f54bdae029", 16);        BigInteger k0 = new BigInteger(bkey);        BigInteger k1 = k0.modPow(pow, mod);        String s0 = Integer.toString(id);        String sz = "0";        while (s0.length() != 5)        {            s0 = sz.concat(s0);        }        s0 = s0.concat("-");        String s1 = encodeGroups(k1);        s0 = s0.concat(s1);        return s0;    }    public static void main(String[] args)    {          String name = "dev";//        if (args.length == 0)//        {//            System.err.printf("*** Usage: %s name%n", keygen.class.getCanonicalName());//            System.exit(1);//        }        Random r = new Random();        System.out.println("regName:"+name);        System.out.println("regCode:"+MakeKey(name, 0, r.nextInt(100000)));    }}

Idea 12 & 13 Registration Code Generator