RSA Chat Messenger(Number Format Exception in Java) -

im doing rsa chat messenger(single server,multiple clients).i have included send,decrypt,exit button.when client sends message 1 client other client.the client recieves message gets in encrypted form , clicks decrypt button original message.but when im clicking decrypt button im getting awt-eventqueue-0" java.lang.numberformatexception , getting wierd characters in decryption section.

here code:

private string bytestostring(byte[] encrypted) {     // todo auto-generated method stub     //return null;     string test = "";     (byte b : encrypted) {         test += byte.tostring(b);     }     return test; }  public static void main(string ... args) {      // take username user     string name = joptionpane.showinputdialog(null,"enter name :", "username",          joptionpane.plain_message);     string servername = "localhost";       try {         new chatclient( name ,servername);     } catch(exception ex) {         out.println( "error --> " + ex.getmessage());     }  } // end of main  // inner class messages thread class  messagesthread extends thread {     public void run() {         string line;         try {             while(true) {                 line = br.readline();                 tamessages.append(line + "\n");             } // end of while         } catch(exception ex) {}     } } public class rsa {      private biginteger p;     private biginteger q;     private biginteger n;     private biginteger phi;     private biginteger e;     private biginteger d;     private int bitlength = 1024;     private int blocksize = 256; //blocksize in byte      private random r;      public rsa() {         r = new random();         p = biginteger.probableprime(bitlength, r);         q = biginteger.probableprime(bitlength, r);         n = p.multiply(q);          phi = p.subtract(biginteger.one).multiply(q.subtract(biginteger.one));         e = biginteger.probableprime(bitlength/2, r);          while (phi.gcd(e).compareto(biginteger.one) > 0 && e.compareto(phi) < 0 ) {             e.add(biginteger.one);         }  d = e.modinverse(phi);      }      public rsa(biginteger e, biginteger d, biginteger n) {         this.e = e;         this.d = d;         this.n = n;     }      private string bytestostring(byte[] encrypted) {         string test = "";         (byte b : encrypted) {             test += byte.tostring(b);         }         return test;     }   //encrypt message      public byte[] encrypt(byte[] message) {              return (new biginteger(message)).modpow(e, n).tobytearray();     }  // decrypt message     public byte[] decrypt(byte[] message) {         return (new biginteger(message)).modpow(d, n).tobytearray();     }  }  class eavesdropper implements actionlistener {     jtextarea mytextarea;             public eavesdropper(jtextarea ta) {         mytextarea = ta;     }        public void actionperformed(actionevent e) {            rsa rsa = new rsa();          //      string teststring = tfinput.gettext();       //    byte[] encrypted = rsa.encrypt(teststring.getbytes());           string text1 = tamessages.gettext();         string[] parts =text1.split("-");            string part1=parts[1];         part1 =part1.replaceall("\n", "");         byte[] b = part1.getbytes();         byte[] decrypted = rsa.decrypt(b);                //rsaencryption rsa=new rsaencryption(1024);     //  biginteger plaintext = new biginteger(part1.getbytes());       //    biginteger ciphertext = rsa.encrypt(plaintext);         //string plaintext3 = rsa.decrypt(part1);         //string text2 = new string(plaintext3.tobytearray());                //    mytextarea.append(plaintext3);         mytextarea.append("decrypted string:" + new string(decrypted));     } }    } //  end of client 

according docs

throws: numberformatexception - val 0 bytes long. 

http://docs.oracle.com/javase/6/docs/api/java/math/biginteger.html#biginteger(byte[])