/*
 * Copyright (C) 1995, 1996 Systemics Ltd (http://www.systemics.com/)
 * All rights reserved.
 *
 */
package cryptix.pgp_examples;

import java.io.*;
import java.util.Date;

import cryptix.math.*;
import cryptix.security.*;
import cryptix.security.rsa.*;
import cryptix.pgp.*;

public class KeyGen implements RSAKeyGenObserver
{
	private static final int MIN_KEY_LENGTH = 384;
	private static final int MAX_KEY_LENGTH = 6000;
	
	protected DataInputStream in;
	protected PrintStream out;
	
	public KeyGen( InputStream in0, PrintStream out0 )
	{
		in = (in0 instanceof DataInputStream) ? (DataInputStream)in0 : new DataInputStream( in0 );
		out = out0;
	}

	public KeyGen()
	{
		this( System.in, System.out );
	}

	public static void
	main( String argv[] )
	{
		new KeyGen().begin();
	}

	protected final void
	begin()
	{
		try
		{
			String name = getUserName();
			int len = getKeyLength();
			RandomStream rs;
			SecretKey gsk = getKey( len, rs = getRandomStream( len ) );
			System.out.println( "Key generated." );
			String passphrase = getPassphrase();
			saveNewKey( gsk, name, passphrase, rs );
		}
		catch( Exception e )
		{
			System.out.println( "Key gen aborted." );
			e.printStackTrace();
		}
	}

	protected SecretKey
	getKey( int length, RandomStream rs )
	{
		return new RSAKeyGen( rs ).createKey( length, this );
	}

	protected String
	getUserName()
	throws IOException
	{
		out.println();
		out.print( "Please enter you user name ? " );
		out.flush();
		String name = in.readLine();
		out.print( "using name  " );
		out.println( name );
		return name;
	}

	protected int
	getKeyLength()
	throws IOException
	{
		while ( true )
		{
			int len;
			out.print( "Please enter key size ( 512, 2048 etc )." );
			out.flush();
			try
			{
				len = Integer.parseInt( in.readLine().trim() );
			}
			catch ( NumberFormatException nfe )
			{
				out.println( "Bad format number try again." );
				continue;
			}
			if ( len < MIN_KEY_LENGTH )
			{
				out.println( "Key bit length too short. (<" + MIN_KEY_LENGTH + ")" );
				continue;
			}
			if ( len > MAX_KEY_LENGTH )
			{
				out.println( "Key bit length too long. (>" + MAX_KEY_LENGTH + ")" );
				continue;
			}
			return len;
		}
	}
	
	/**
	 * This is NOT VERY SECURE as the seed is rather simplistic.
	 */
	protected RandomStream
	getRandomStream( int keyLength )
	throws IOException
	{
		int min = ( ( keyLength / 6 ) + 10 );
		ByteArrayOutputStream seedBuffer = new ByteArrayOutputStream( 8192 );
		PrintStream seedout = new PrintStream( seedBuffer );
		seedout.print( new Date() );
		seedout.println( "Please enter some random data" );
		out.print( "You will have to enter a minimum of " );
		out.print( min );
		out.println( " characters;" );
		seedout.print( System.currentTimeMillis() );
		SHA sha = new SHA();
		MD5 md5 = new MD5();
		while ( min > 0 )
		{
			String data = in.readLine();
			sha.add( Long.toString( System.currentTimeMillis() ) ); 
			sha.add( data );
			min -= data.length();
			seedout.print( min );
			seedout.print( data.length() );
			seedout.print( System.currentTimeMillis() );
			seedout.print( data );
			out.print( "characters to go " );
			out.println( min < 0 ? 0 : min );
			md5.add( data );
			md5.add( Long.toString( System.currentTimeMillis(), 16 ) ); 
		}
		try
		{
			seedout.write( sha.digest() );
			seedout.write( md5.digest() );
		}
		catch ( IOException ioe )
		{
			ioe.printStackTrace( seedout );
		}

		return new CSRandomStream( SHA.hash( seedBuffer.toByteArray() ) );
	}
	
	/**
	 * WARNING this prints the passphrase out on to the screen.
	 */
	protected String
	getPassphrase()
	throws IOException
	{
		String passphrase = "";
		while( true )
		{
			out.print( " please enter passphrase " );
			out.flush();
			String pass1 = in.readLine();
			out.print( " please re-enter passphrase " );
			out.flush();
			passphrase = in.readLine();
			if ( pass1.equals( passphrase ) )
				return passphrase;
			out.println( "Passphrases do not match." );
			out.println( "Please try again." );
		}
	}
	
	private final void
	saveNewKey( SecretKey gsk, String name, String passphrase, RandomStream rs )
	throws IOException
	{	
		FileOutputStream pubring;
		FileOutputStream secring;

		UserId username = new UserId( name );

		DataOutputStream pub = new DataOutputStream( pubring = new FileOutputStream( "pubring.pgp" ) );

		PublicKeyCertificate pkc = new PublicKeyCertificate( gsk ); // sk isa pk.
		PacketFactory.write( pub, pkc );
		PacketFactory.write( pub, new KeyRingTrust( (byte)0x87 ) );
		PacketFactory.write( pub, username );
		PacketFactory.write( pub, new KeyRingTrust( (byte)0x03 ) );
		pubring.close();

		DataOutputStream sec = new DataOutputStream( secring = new FileOutputStream( "secring.pgp" ) );
		SecretKeyCertificate skc = new SecretKeyCertificate( gsk, new Passphrase( passphrase ) , rs );
		PacketFactory.write( sec, skc );
		PacketFactory.write( sec, username );
		secring.close();
	}
	
	public void handleEvent( int evnt )
	{
		switch ( evnt )
		{
		case HAS_SMALL_FACTORS:
			out.print( "-" );
			out.flush();
			break;

		case NOT_PRIME:
			out.print( "+" );
			out.flush();
			break;

		case IS_PRIME:
			out.print( "*" );
			out.flush();
			break;

		case FINDING_P:
			out.println();
			out.print( "p:" );
			out.flush();
			break;

		case FINDING_Q:
			out.println();
			out.print( "q:" );
			out.flush();
			break;

		case KEY_RESOLVING:
			out.println( "Key resolving begins" );
			break;

		case NO_SMALL_FACTORS:
		case KEY_GEN_DONE:
			break;

		default:
			out.println( "Unexpected event : " + evnt );
			break;
		}
	}
}