// Create HMAC of the current time, user, and uid

import java.io.*;
import javax.crypto.*;
import javax.crypto.spec.*;

public class IOticket
{
  /* hex conversion code adapted from cryptix.util.core.Hex */

  private static final char[] hexDigits = {
    '0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'
  };

  // convert byte array to hex
  //
  public static String hex(byte[] ba)
  {
    char[] buf = new char[ba.length * 2];
    int j = 0;
    int k;

    for (int i = 0; i < ba.length; i++) {
      k = ba[i];
      buf[j++] = hexDigits[(k >>> 4) & 0x0F];
      buf[j++] = hexDigits[ k        & 0x0F];
    }

    return new String(buf);
  }

  public static void main( String[] args) throws Exception
  {
    if( args.length != 2)
    {
      System.err.println( "Usage: IOticket user uid");
      System.exit(1);
    }

    String user = args[0];
    String uid = args[1];

    if( user.length() < 1 || uid.length() < 1)
      throw new IllegalArgumentException( "user or uid is empty");

    FileInputStream fin = new FileInputStream( "secret.dat");
    byte secret[] = new byte[64];
    int n = fin.read( secret);
    fin.close();

    if( n < 64)
      throw new SecurityException( "secret.dat is too small");
 
    SecretKeySpec KS = new SecretKeySpec( secret, "HmacSHA256");
    Mac mac = Mac.getInstance( "HmacSHA256");
    mac.init( KS);

    String time = Long.toString(System.currentTimeMillis());

    mac.update( time.getBytes());
    mac.update( user.getBytes());
    mac.update( uid.getBytes());

    String ticket = hex( mac.doFinal());

    System.out.println( "<param name=\"user\" value=\"" + user + "\">");
    System.out.println( "<param name=\"uid\" value=\"" + uid + "\">");
    System.out.println( "<param name=\"time\" value=\"" + time + "\">");
    System.out.println( "<param name=\"ticket\" value=\"" + ticket + "\">");
  }

}