rsa.java

rsa算法演示

	private JTextField d;
	private JTextField e;
	private JTextArea input;
	private JTextArea output;
}

class DecodeListener implements ActionListener
{
	public DecodeListener(JTextField aP, JTextField aQ, JTextField ad, JTextField ae,
			JTextArea out, JTextArea out1)
	{
		P = aP;
		Q = aQ;
		d = ad;
		e = ae;
		output = out;
		output1 = out1;
	}
	public void actionPerformed(ActionEvent ee)
	{
		// TODO
		BigInteger PrimeP = new BigInteger(P.getText());
		BigInteger PrimeQ = new BigInteger(Q.getText());
		BigInteger n =PrimeP.multiply(PrimeQ);
		int nLen = n.bitLength();
		int m=(int)(Math.ceil((double)(nLen)/16.0));
		nLen = (nLen-1) / 16;
		String inStr = output.getText();
		output1.setText(PublicMethod.Decode(inStr,PrimeP,PrimeQ,n,nLen,m,d));
	}
	private JTextField P;
	private JTextField Q;
	private JTextField d;
	private JTextField e;
	private JTextArea output;
	private JTextArea output1;
}

class PublicMethod
{
	public static void GetPrime( JTextField prime )
	{
		BigInteger num = new BigInteger("0");
		Random rand = new Random();
		do
		{
			int length = (int)(Math.random()*20+100);
			System.out.println(length);
			num = new BigInteger( length, 5 , rand );
			prime.setText(num.toString());
		}
		while(MillerRobin(num)==false);
	}
	
	public static boolean MillerRobin(BigInteger num)
	{
		int time = 1000;
		BigInteger mod = num.mod(new BigInteger("2"));
		if(mod.equals(new BigInteger("0")))
		{
			return false;
		}
		int s = 0, j=0;
		BigInteger t=num.subtract(new BigInteger("1"));
		while( t.mod(new BigInteger("2")).equals("0") )
		{
			t.divide(new BigInteger("2"));
			++s;
		}
		for(int i=0; i<time; ++i)
		{
			BigInteger a = new BigInteger(100, new Random()).mod(num.subtract(new BigInteger("3"))).add(new BigInteger("2"));
			BigInteger y = powmod(a, t, num);
			if(y.equals(new BigInteger("1"))==false
			&& y.equals(num.subtract(new BigInteger("1")))==false)
			{
				j=1;
				while(j<=s&&y.equals(num.subtract(new BigInteger("1")))==false)
				{
					y = y.multiply(y).mod(num);
					if(y.equals(new BigInteger("1")))
					{
						return false;
					}
					++j;
				}
				if(y.equals(num.subtract(new BigInteger("1")))==false)
				{
					return false;
				}
			}
		}
		return true;
	}
	
	public static BigInteger powmod( BigInteger a, BigInteger t, BigInteger num )
	{
		BigInteger A = new BigInteger("1");
		while(t.equals(new BigInteger("0"))==false)
		{
			if(t.mod(new BigInteger("2")).equals(new BigInteger("1")))
			{
				A = A.multiply(a).mod(num);
			}
			a = a.multiply(a).mod(num);
			t=t.divide(new BigInteger("2"));
		}
		return A;
	}
	
	public static BigInteger invmod(BigInteger a, BigInteger b)
	{
		System.out.println(a+" "+b);
		BigInteger s0=new BigInteger("1"), s1=new BigInteger("0"), s2, q, t, b0=b;
		while(b.equals(new BigInteger("0"))==false)
		{
			q=a.divide(b);
			s2=s0.subtract(  q.multiply(s1)  );
			if(s2.compareTo(new BigInteger("0"))!=-1)
			{
				s2=s2.mod(b0);
			}
			else
			{
				s2=b0.subtract( s2.multiply(new BigInteger("-1")).mod(b0) );
			}
			s0=s1;
			s1=s2;
			t=b;
			b=a.mod(b);
			a=t;
		}
		if(a.equals(new BigInteger("1")))
		{
			return s0;
		}
		else
		{
			return new BigInteger("0");
		}
	}
	
	public static String Encode(String inStr,BigInteger PrimeP,BigInteger PrimeQ,
								BigInteger n,int nLen,int m,JTextField d)
	{
		BigInteger res = new BigInteger("0");
	    StringBuffer outBuf = new StringBuffer();
	    int i,k,j;
        for(i=0;i<inStr.length();i=j)
        {
			BigInteger t = new BigInteger("0");
        	for(j=i;j<i+nLen&&j<inStr.length();j++)
        	{
        		t=t.shiftLeft(16);
        		long num = inStr.charAt (j);
        		t=t.add(BigInteger.valueOf(num));
        	}					 	      	  	
            res = PublicMethod.powmod(t,new BigInteger(d.getText()),n);                 
            String buf = new String();
            for(k=0;k<m;++k)
            {
                
                long num = (res.and(BigInteger.valueOf(65535))).longValue();
                res = res.shiftRight(16);		
            	buf = (char)(num)+buf;
            }	
        	outBuf = outBuf.append(buf);
        }		
		return outBuf.toString();
	}
	
	public static String Decode(String inStr,BigInteger PrimeP,BigInteger PrimeQ,
								BigInteger n,int nLen,int m,JTextField e)
	{
		StringBuffer outBuf = new StringBuffer();
		BigInteger res = new BigInteger("0");
		int i,j;
		for(i=0;i<inStr.length();i+=j)
		{
			BigInteger t = new BigInteger("0");
			for(j=0;j<m&&j+i<inStr.length();j++)
			{
				t =  t.shiftLeft(16);
				long num =(long)(inStr.charAt (j+i));	
				t=t.add(BigInteger.valueOf(num));
			}	
			res = PublicMethod.powmod(t,new BigInteger(e.getText()),n);	
			String buf = new String();
			while(res.compareTo(new BigInteger("0"))>0)
			{
				long num =(res.and(BigInteger.valueOf(65535))).longValue();
				buf =  (char)(num) + buf;
				res = res.shiftRight(16)	;
			}
			outBuf =  outBuf.append(buf);
		}		
		return outBuf.toString();
	}
	

	public static String read(String infileName)
	{
		String ans =  new String ();
		try
		{
	    	//BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream (infileName)));
			
			FileInputStream fis = new FileInputStream(infileName);
			InputStreamReader isr = new InputStreamReader(fis); 
			BufferedReader br = new BufferedReader (isr);
			int t;
			while(true)
			{
				t= br.read();
				System.out.println(t);
				if(t==-1)  break;
				ans = ans + (char)(t);	
			}
		    /*

			byte b[] = new byte[1024];
			int by;
			int len=0;

			while(true)
			{
				by = fis.read();
				if(by==-1)  break;
				else b[len++]=(byte)by;
			}
			
			//System.out.println("byte"+b);
			//System.out.println("len="+b.length);
			String temp = new String(b,0,len);
			//System.out.println("Sytem="+temp);
			ans = temp;
			*/
			br.close();
			isr.close();	
			fis.close();

		}
		catch(FileNotFoundException e)
		{
    		System.out.println("FileStreamsTest: "+e);
		}
		catch(IOException e) 
		{
			System.err.println("FileStreamsTest: "+e);
		}
		System.out.println("READSTR="+ans.length());		
		return ans;
	}
	public static void write(String outfileName,String outStr)
	{
		
		try
		{
			/*
			/*
			PrintWriter out = new PrintWriter(new OutputStreamWriter(new FileOutputStream(outfileName)));
			out.print(outStr);
			out.close();
			*/
			FileOutputStream fos = new FileOutputStream(outfileName);
			OutputStreamWriter osw = new OutputStreamWriter(fos,"UNICODE"); 
			BufferedWriter out = new BufferedWriter (osw);  
            
            int c;
	  		for(int i=0;i<outStr.length();i++)
	  		{
	  			c=(int)outStr.charAt(i);
	  			System.out.println(c);
	  			out.write(c);
	  			//out.flush();
	  		}
			out.close();
			osw.close();
			fos.close();
	  		
	  		//System.out.println("=========================");
	  		//System.out.println(outStr);
	  		//System.out.println("=========================");
	  		//byte[] by = outStr.getBytes();
	  		
	  	//	System.out.println("byte="+by.length);
	  		//System.out.println("=========================");
	  		//fos.write(by);
	  		//out.write()
	  		//out.close();
			//fos.close();
			/*
			/////////////////////////////////////////////////////
			File file = new File(outfileName);
			if(!file.exists()) file.createNewFile();
			FileWriter fw=new FileWriter(file);
			PrintWriter pw = new PrintWriter (fw);
			pw.print(outStr);
			pw.close();
			fw.close();
			//////////////////////////////////////////////////////
		    */
		}
		catch(FileNotFoundException e)
		{
    		System.out.println("FileStreamsTest: "+e);
		}
		catch(IOException e) 
		{
			System.err.println("FileStreamsTest: "+e);
		}
		System.out.println("WRITE="+outStr.length());
		return ;
	}
    
	public static String input(String infileName)
	{
		String ans = new String();
		try
		{
		
			FileInputStream in = new FileInputStream(infileName); 
    		ObjectInputStream s = new ObjectInputStream(in); 
    		ans = (String)s.readObject();
			s.close();
			in.close();

		} 
		catch(FileNotFoundException e)
		{
    		System.out.println("FileStreamsTest: "+e);
		}
		catch(IOException e) 
		{
			System.err.println("FileStreamsTest: "+e);
		}
		catch(ClassNotFoundException e)
		{
			System.out.println("FileStreamsTest: "+e);
		}
		return ans;
	}
	
	public static void output(String outfileName,String outStr)
	{
		try
		{
			FileOutputStream f = new FileOutputStream(outfileName); 
    		ObjectOutputStream s = new ObjectOutputStream(f); 
    		s.writeObject(outStr);
    		s.close();
    		f.close(); 
		}
		catch(FileNotFoundException e)
		{
    		System.out.println("FileStreamsTest: "+e);
		}
		catch(IOException e) 
		{
			System.err.println("FileStreamsTest: "+e);
		}	
	}
	
}