java decryption algorithm giving java.lang.ArrayIndexOutOfBoundsException: -59 -

i have decryption algorithm , compiles exception while running it.

i've tried changing order of (byte) , adding more in can't seem figure out why isn't working.

below crypt.java code:

public class crypt implements runnable {     public crypt(byte[] data, int length, byte[] key) throws ioexception {         byte v3, v5, v6;         int len = length;          if (len > 0) {             {                 --len;                 v3 = (byte) (key[0] + 1);                 key[0] = v3;                 v5 = (byte) (key[4] + key[8 + v3]);                 key[4] = v5;                 v6 = key[8 + v3];                 key[8 + v3] = key[8 + v5];                 key[8 + key[4]] = v6;                  data[length - len - 1] ^= key[8 + (byte) (key[8 + key[4]] + key[8 + key[0]])];                  log.loginfo("packet data: " + datatypeconverter.printhexbinary(data) + "");             }             while (len > 0);         }     }      public void run() {     } } 

and below code using crypt.java run.

byte key[] = {     (byte) 0x2b, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0xda, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x58, (byte) 0x24, (byte) 0x32, (byte) 0x6a, (byte) 0xc3, (byte) 0x06, (byte) 0x1b, (byte) 0x2c,     (byte) 0x6b, (byte) 0x61, (byte) 0x3e, (byte) 0xaf, (byte) 0xec, (byte) 0x31, (byte) 0x60, (byte) 0x38, (byte) 0x05, (byte) 0x46, (byte) 0x04, (byte) 0x0c, (byte) 0x2b, (byte) 0xb9, (byte) 0x6e, (byte) 0x2e,     (byte) 0x07, (byte) 0x5d, (byte) 0xff, (byte) 0xe8, (byte) 0x64, (byte) 0xe3, (byte) 0x70, (byte) 0x40, (byte) 0xdb, (byte) 0x93, (byte) 0xda, (byte) 0xcc, (byte) 0x01, (byte) 0x18, (byte) 0x22, (byte) 0x5e,     (byte) 0xdf, (byte) 0x94, (byte) 0x5a, (byte) 0x4f, (byte) 0x25, (byte) 0xbe, (byte) 0x1d, (byte) 0xb5, (byte) 0x4b, (byte) 0xb4, (byte) 0x17, (byte) 0x8b, (byte) 0xf4, (byte) 0x57, (byte) 0x39, (byte) 0xb3,     (byte) 0xfe, (byte) 0x91, (byte) 0x63, (byte) 0x7d, (byte) 0x1c, (byte) 0x9f, (byte) 0x7a, (byte) 0xca, (byte) 0x3a, (byte) 0x1e, (byte) 0x65, (byte) 0xa7, (byte) 0x68, (byte) 0xd1, (byte) 0x89, (byte) 0x78,     (byte) 0x67, (byte) 0x43, (byte) 0xf3, (byte) 0xb2, (byte) 0x8d, (byte) 0xd9, (byte) 0x8e, (byte) 0x9e, (byte) 0x9c, (byte) 0xc9, (byte) 0xe9, (byte) 0x9b, (byte) 0xb6, (byte) 0xba, (byte) 0x75, (byte) 0x20,     (byte) 0x74, (byte) 0xd3, (byte) 0x3f, (byte) 0x88, (byte) 0x56, (byte) 0x6d, (byte) 0x41, (byte) 0x62, (byte) 0x2a, (byte) 0xc6, (byte) 0xa2, (byte) 0xc5, (byte) 0x5f, (byte) 0x7b, (byte) 0x33, (byte) 0xc4,     (byte) 0xf6, (byte) 0x3b, (byte) 0xef, (byte) 0x97, (byte) 0x95, (byte) 0x92, (byte) 0x87, (byte) 0xc7, (byte) 0xf7, (byte) 0x52, (byte) 0x7f, (byte) 0x10, (byte) 0xa8, (byte) 0xdc, (byte) 0x45, (byte) 0xd0,     (byte) 0xfd, (byte) 0x99, (byte) 0x9d, (byte) 0xe0, (byte) 0x0e, (byte) 0x29, (byte) 0x6c, (byte) 0x81, (byte) 0x83, (byte) 0xd5, (byte) 0xe7, (byte) 0xee, (byte) 0xfa, (byte) 0x59, (byte) 0xa9, (byte) 0x27,     (byte) 0x26, (byte) 0xcd, (byte) 0xdd, (byte) 0xae, (byte) 0x09, (byte) 0x44, (byte) 0x30, (byte) 0x47, (byte) 0xe5, (byte) 0xf0, (byte) 0x37, (byte) 0x5b, (byte) 0x13, (byte) 0x4a, (byte) 0x96, (byte) 0x4e,     (byte) 0x72, (byte) 0xa6, (byte) 0x79, (byte) 0xd4, (byte) 0xa4, (byte) 0x98, (byte) 0x36, (byte) 0xe6, (byte) 0x86, (byte) 0xd7, (byte) 0x28, (byte) 0x02, (byte) 0xf9, (byte) 0x2d, (byte) 0xbc, (byte) 0x12,     (byte) 0xed, (byte) 0xbf, (byte) 0xad, (byte) 0x48, (byte) 0xce, (byte) 0x84, (byte) 0x82, (byte) 0x7c, (byte) 0xfb, (byte) 0x53, (byte) 0xe2, (byte) 0xea, (byte) 0x0d, (byte) 0x14, (byte) 0x1f, (byte) 0x54,     (byte) 0xaa, (byte) 0x08, (byte) 0x23, (byte) 0xf2, (byte) 0x21, (byte) 0x4c, (byte) 0x8c, (byte) 0x3d, (byte) 0xbd, (byte) 0xa1, (byte) 0x35, (byte) 0xb7, (byte) 0x55, (byte) 0x42, (byte) 0x4d, (byte) 0xa5,     (byte) 0x8f, (byte) 0x3c, (byte) 0x85, (byte) 0xc8, (byte) 0x77, (byte) 0x03, (byte) 0x0a, (byte) 0x1a, (byte) 0x11, (byte) 0x15, (byte) 0x00, (byte) 0xc0, (byte) 0xb1, (byte) 0xeb, (byte) 0x5c, (byte) 0x71,     (byte) 0xd8, (byte) 0xc2, (byte) 0x8a, (byte) 0x0f, (byte) 0x76, (byte) 0x50, (byte) 0xa0, (byte) 0x19, (byte) 0x73, (byte) 0xf5, (byte) 0xfc, (byte) 0x0b, (byte) 0x69, (byte) 0xe1, (byte) 0x90, (byte) 0xd2,     (byte) 0xab, (byte) 0xc1, (byte) 0x9a, (byte) 0x51, (byte) 0x6f, (byte) 0x34, (byte) 0x80, (byte) 0xb8, (byte) 0xa3, (byte) 0xd6, (byte) 0xcb, (byte) 0xe4, (byte) 0xcf, (byte) 0x2f, (byte) 0xf8, (byte) 0xbb,     (byte) 0x16, (byte) 0x66, (byte) 0xb0, (byte) 0x49, (byte) 0xac, (byte) 0xde, (byte) 0xf1, (byte) 0x7e };  new thread(new crypt(request, size, key)).start(); 

the variable request above code byte. size variable length of request variable.

i've spent countless hours working on , have no clue why isn't working.

when program runs below exception:

exception in thread "thread-3" java.lang.arrayindexoutofboundsexception: -59         @ com.webraid.cocproxy.utils.crypt.<init>(crypt.java:33)         @ com.webraid.cocproxy.network.client.run(client.java:97)         @ java.lang.thread.run(unknown source) 

"packet data" printed out twice. once before put through crypt.java file , after can see in code. 2 results similar first 2 values changed.

in case 02 became 1a.

edit:

line 33 in crypt.java is: key[8 + v3] = key[8 + v5];

and line 97 in client.java code is: new thread(new crypt(request, size, key)).start();

adding output here:

 packet data: 023e12aff65cafe52fb389f8fffb7eafea81e672159dd38cdcf26a44895871b727ceb02976e85f658472c66ada79cb49b47340523e643f0dfb3d4e5c7b5b1239296e26313  5a2bb400fdd9e935d4255fe4cf0ff4bd87ed6359896a82b50753e3a3a9a998217640e1247c3af153afcf2e6351de55aeffad000af98549a28da8823928a4496582476e29adeb942634c68c  291a711ca140be4403f76f6f827e22204755396d0f546702ed20c3595a37d2a8b529963bd505ff34521792510dd27225fc1758b17da6936f2eccbad7e55425b3f5328aa503df610484b018  8289d36ed777b6641a4a765743eac6e0d8e8a28510d3caaf18b2d   packet data: 1a3e12aff65cafe52fb389f8fffb7eafea81e672159dd38cdcf26a44895871b727ceb02976e85f658472c66ada79cb49b47340523e643f0dfb3d4e5c7b5b1239296e26313  5a2bb400fdd9e935d4255fe4cf0ff4bd87ed6359896a82b50753e3a3a9a998217640e1247c3af153afcf2e6351de55aeffad000af98549a28da8823928a4496582476e29adeb942634c68c  291a711ca140be4403f76f6f827e22204755396d0f546702ed20c3595a37d2a8b529963bd505ff34521792510dd27225fc1758b17da6936f2eccbad7e55425b3f5328aa503df610484b018  8289d36ed777b6641a4a765743eac6e0d8e8a28510d3caaf18b2d 

the issue on:

v5 = (byte) (key[4] + key[8 + v3]); v6 = key[8 + v3]; key[8 + v3] = key[8 + v5]; key[8 + key[4]] = v6;   ....key[8 + (byte)(key[8 + key[4]] + key[8 + key[0]])] 

with data on second loop key[8 + v3] means k[-59]. java byte signed, can have negative values on bytes. also, not sure bytes on key between 0 , key.lenght().

you should review crypt alghorithm ensure stay in boundary of 'key' array.

a possibile solution use method 'normalize' input stay on range 0-key.lenght:

ex.

private int normalizeindex(byte[] key, int index){         return math.abs(index)%(key.length-1);     } 

then use when retrieve array cells:

...  v6 = key[normalizeindex(key,8 + v3)];  key[ normalizeindex(key,(8 + v3))] = key[ normalizeindex(key,(8 + v5))];  key[normalizeindex(key,8 + key[4])] = v6;   data[length - len - 1] ^= key[normalizeindex(key,8+(int)(key[ normalizeindex(key,8 + key[4])]) + key[ normalizeindex(key,8 + key[0])])]; ... 

hope helped you!