/* *   File:  ElGamalKeys.java * *   ElGamal key generation routines and constants. * *   version 1.02 v1a *   Copyright 1998, 1999 by Hush Communications Corporation, BWI */package hushcode;import java.math.BigInteger;final class ElGamalKeys{   // 1024-bit pre-generated p and g (actually 1038 bit, but who's counting?)   private BigInteger p = new BigInteger (      "20f2221cdf61a1ccf248858184cbaf20119daba6044d9370837e8e7c2d67efd81758066"+      "9408903f0fcebb2f08f3789365020bbeb116736bca1d09f5a5d9d7e85b8e750dd24149d"+      "ec8be0cd6c039386112d3924fa07d1b3eaad4196f6dad0c6bba953477a466504ca62a4e"+      "44f1a22cc704857c742913f971451e787601bd9fd41e6f5" , 16 );   private BigInteger g = new BigInteger (      "20ba729a42aacbdcf18103276f16980068c06649be0ac0891f0e23b2b79cf7e4eb31a3d"+      "07f0444348327ee1042d81f568dbd4397652b9685175bcbc4355ee8e07bb2d349ed55c2"+      "609e9b6f7bb972eedbaee1c07e3a5e01ccd18fc88ce67a883a11a4016b9f09a3a5ae1b5"+      "102c298bdbaee16a06b670eec1518ba57bce6b6685c96e4" , 16 );   private BigInteger x;  // the Private key   private BigInteger y;  // the Public key   private int s = 130;   // Length of modulus in bytes (1040 bits)   private int strength = 1024;  // Length of private key in bits   /* Class constructor.    * Holds p, g, x, and y.    * p and g are constants.  Given x (totally random), we generate y.    */   ElGamalKeys(byte[] privKey)   {      privKey[0] = (byte) ( privKey[0] & 0x7f);      x = new BigInteger(privKey);         //  Make sure x is < p, btw...      x = x.setBit(strength - 1);          //  give x 1024 significant bits...      y = g.modPow(x,p);                   //  Create y, the Public key.   }   //  Returns y in a byte array the length of the modulus.   byte[] publicKey()   {      byte[] yy = y.toByteArray();        int yl = yy.length;      if (yl == s)  return yy;      //  Copy y to key, making sure it's s bytes in length      byte[] key = new byte[s];      for (int n=0; n<s; n++)      {         if (n >= s-yl)            key[n] = yy[n-(s-yl)];         else            key[n]=0;      }      return key;   }   //  Returns x in a byte array the length of the modulus.   byte[] privateKey()   {      byte[] xx = x.toByteArray();        int xl = xx.length;      if (xl == s)  return xx;      //  Copy x to key, making sure it's s bytes in length      byte[] key = new byte[s];      for (int n=0; n<s; n++)      {         if (n >= s-xl)            key[n] = xx[n-(s-xl)];         else            key[n]=0;      }      return key;   }}  //  end ElGamalKeys