1 package keygen;  2   3 import java.math.BigInteger;  4 import java.util.Date;  5 import java.util.zip.CRC32;  6   7 public class Keygen {  8   9     private static final int version = 14; 10  11     /** 12      * @param s 13      * @param i 14      * @param bytes 15      * @return 16      */ 17     public static short getCRC(String s, int i, byte bytes[]) { 18         CRC32 crc32 = new CRC32(); 19         if (s != null) { 20             for (int j = 0; j < s.length(); j++) { 21                 char c = s.charAt(j); 22                 crc32.update(c); 23             } 24         } 25         crc32.update(i); 26         crc32.update(i >> 8); 27         crc32.update(i >> 16); 28         crc32.update(i >> 24); 29         for (int k = 0; k < bytes.length - 2; k++) { 30             byte byte0 = bytes[k]; 31             crc32.update(byte0); 32         } 33         return (short) (int) crc32.getValue(); 34     } 35  36     /** 37      * @param biginteger 38      * @return String 39      */ 40     public static String encodeGroups(BigInteger biginteger) { 41         BigInteger beginner1 = BigInteger.valueOf(0x39aa400L); 42         StringBuilder sb = new StringBuilder(); 43         for (int i = 0; biginteger.compareTo(BigInteger.ZERO) != 0; i++) { 44             int j = biginteger.mod(beginner1).intValue(); 45             String s1 = encodeGroup(j); 46             if (i > 0) { 47                 sb.append("-"); 48             } 49             sb.append(s1); 50             biginteger = biginteger.divide(beginner1); 51         } 52         return sb.toString(); 53     } 54  55     /** 56      * @param i 57      * @return 58      */ 59     public static String encodeGroup(int i) { 60         StringBuilder sb = new StringBuilder(); 61         for (int j = 0; j < 5; j++) { 62             int k = i % 36; 63             char c; 64             if (k < 10) { 65                 c = (char) (48 + k); 66             } else { 67                 c = (char) ((65 + k) - 10); 68             } 69             sb.append(c); 70             i /= 36; 71         } 72         return sb.toString(); 73     } 74  75     /** 76      * @param name 77      * @param days 78      * @param id 79      * @return 80      */ 81     public static String MakeKey(String name, int days, int id) { 82         id %= 100000; 83         byte bkey[] = new byte[12]; 84         bkey[0] = (byte) 1; // Product type: IntelliJ IDEA is 1 85         bkey[1] = version; 86         Date d = new Date(); 87         long ld = (d.getTime() >> 16); 88         bkey[2] = (byte) (ld & 255); 89         bkey[3] = (byte) ((ld >> 8) & 255); 90         bkey[4] = (byte) ((ld >> 16) & 255); 91         bkey[5] = (byte) ((ld >> 24) & 255); 92         days &= 0xffff; 93         bkey[6] = (byte) (days & 255); 94         bkey[7] = (byte) ((days >> 8) & 255); 95         bkey[8] = 105; 96         bkey[9] = -59; 97         bkey[10] = 0; 98         bkey[11] = 0; 99         int w = getCRC(name, id % 100000, bkey);100         bkey[10] = (byte) (w & 255);101         bkey[11] = (byte) ((w >> 8) & 255);102         BigInteger pow = new BigInteger("89126272330128007543578052027888001981", 10);103         BigInteger mod = new BigInteger("86f71688cdd2612ca117d1f54bdae029", 16);104         BigInteger k0 = new BigInteger(bkey);105         BigInteger k1 = k0.modPow(pow, mod);106         String s0 = Integer.toString(id);107         String sz = "0";108         while (s0.length() != 5) {109             s0 = sz.concat(s0);110         }111         s0 = s0.concat("-");112         String s1 = encodeGroups(k1);113         s0 = s0.concat(s1);114         return s0;115     }116 }

            Random r = new Random();            String key = MakeKey(userName, 0, r.nextInt(Integer.MAX_VALUE));