//**********************************************
//
// RSAPVK8
// PKCS #8 PrivateKeyInfo dumper
//
// Copyright (C) 2004  Michel I. Gallant
//
//**********************************************

import java.io.*;
import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;
import java.security.cert.*;
import java.security.interfaces.*;


class RSAPVK8 {

  public static void main(String[] args) {
   if (args.length != 1)
	System.out.println("Usage: RSAPVK8 <PKCS#8PrivateKey>");
   else 
   try
	{	 
	 byte[] encodedPriKey = getFileBytes(args[0]);
	 System.out.println("RSA PrivateKeyInfo: " + encodedPriKey.length + " bytes\n") ;
	 PKCS8EncodedKeySpec pvkKeySpec = new PKCS8EncodedKeySpec(encodedPriKey);
	 KeyFactory keyFactory = KeyFactory.getInstance("RSA");

	 //---- First, display private key components using default hex display of Crt toString() --
	 RSAPrivateKey mypvkKey = (RSAPrivateKey)keyFactory.generatePrivate(pvkKeySpec);
	 System.out.println(mypvkKey.toString()) ;


	 //---- Second, manually display private key components in BigInteger decimal format  --
	 RSAPrivateCrtKey pvkKey = (RSAPrivateCrtKey)keyFactory.generatePrivate(pvkKeySpec);

	 BigInteger mod = pvkKey.getModulus();
	 byte[] modbytes = mod.toByteArray() ;
	 if(modbytes[0] == 0)   //if high-order byte is zero, it's for sign bit; don't count in bit-size calculation
		System.out.println("\nKeySize: " + 8*(modbytes.length-1) + " bits");
	 else
		System.out.println("\nKeySize: " + 8*modbytes.length + " bits");

	 System.out.println("\nModulus:\n" + pvkKey.getModulus().toString());
	 System.out.println("\nPublic Exponent:\n" + pvkKey.getPublicExponent().toString());
	 System.out.println("\nPrivate Exponent:\n" + pvkKey.getPrivateExponent().toString());
	 System.out.println("\nPrime Exponent P:\n" + pvkKey.getPrimeExponentP().toString());
	 System.out.println("\nPrime Exponent Q:\n" + pvkKey.getPrimeExponentQ().toString());
	 System.out.println("\nPrime P:\n" + pvkKey.getPrimeP().toString());
	 System.out.println("\nPrime Q:\n" + pvkKey.getPrimeQ().toString());
	 System.out.println("\nCrtCoeff:\n" + pvkKey.getCrtCoefficient().toString());

    }
   catch(Exception ioe)
	{
	 System.out.println(ioe.toString());
	}
 }


  private static void displayData(byte[] data)
  {
	int bytecon = 0;    //to get unsigned byte representation
	for(int i=1; i<=data.length ; i++){
		bytecon = data[i-1] & 0xFF ;   // byte-wise AND converts signed byte to unsigned.
           if(bytecon<16)
            System.out.print("0" + Integer.toHexString(bytecon).toUpperCase() + " ");   // pad on left if single hex digit.
            else
            System.out.print(Integer.toHexString(bytecon).toUpperCase() + " ");   // pad on left if single hex digit.
		if(i%16==0)
		  System.out.println();
	  }
  }



 private static byte[] getFileBytes(String infile){
  File f = new File(infile) ;
  int sizecontent = ((int) f.length());
  byte[] data = new byte[sizecontent];
  try 
	{
	FileInputStream freader = new FileInputStream(f);
	freader.read(data, 0, sizecontent) ;
	freader.close();
	return data;
	}
  catch(IOException ioe)
	 {
	System.out.println(ioe.toString());
	return null;
	}
}


}