RSA算法实现JAVA源代码

filename:RSA.java

/*
* Created on Mar 3, 2005
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/

import java.math.BigInteger;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.BufferedReader;
import java.util.StringTokenizer;

/**
* @author Steve
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
*/
public class RSA {
   
     /**
     * BigInteger.ZERO
      */
     private static final BigInteger ZERO = BigInteger.ZERO;
   
     /**
     * BigInteger.ONE
      */
     private static final BigInteger ONE = BigInteger.ONE;
   
     /**
     * Pseudo BigInteger.TWO
      */
     private static final BigInteger TWO = new BigInteger( " 2 " );
   
     private BigInteger myKey;
   
     private BigInteger myMod;
   
     private int blockSize;
   
     public RSA (BigInteger key, BigInteger n, int b) {
        myKey = key;
        myMod = n;
        blockSize = b;
    }
   
     public void encodeFile (String filename) {
         byte [] bytes = new byte [blockSize / 8 + 1 ];
         byte [] temp;
         int tempLen;
        InputStream is = null ;
        FileWriter writer = null ;
         try {
             is = new FileInputStream(filename);
             writer = new FileWriter(filename + " .enc " );
        }
         catch (FileNotFoundException e1){
            System.out.println( " File not found: " + filename);
        }
         catch (IOException e1){
            System.out.println( " File not found: " + filename + " .enc " );
        }
       
         /**
         * Write encoded message to 'filename'.enc
          */
         try {
             while ((tempLen = is.read(bytes, 1 , blockSize / 8 )) > 0 ) {
                 for ( int i = tempLen + 1 ; i < bytes.length; ++ i) {
                    bytes[i] = 0 ;
                }
                writer.write(encodeDecode( new BigInteger(bytes)) + " " );
            }
        }
         catch (IOException e1) {
            System.out.println( " error writing to file " );
        }
       
         /**
         * Close input stream and file writer
          */
         try {
            is.close();
            writer.close();
        }
         catch (IOException e1) {
            System.out.println( " Error closing file. " );
        }
    }
   
     public void decodeFile (String filename) {
       
        FileReader reader = null ;
        OutputStream os = null ;
         try {
            reader = new FileReader(filename);
            os = new FileOutputStream(filename.replaceAll( " .enc " , " .dec " ));
        }
         catch (FileNotFoundException e1) {
             if (reader == null )
                System.out.println( " File not found: " + filename);
             else
                System.out.println( " File not found: " + filename.replaceAll( " .enc " , " dec " ));
        }
       
        BufferedReader br = new BufferedReader(reader);
         int offset;
         byte [] temp, toFile;
        StringTokenizer st = null ;
         try {
             while (br.ready()) {
                st = new StringTokenizer(br.readLine());
                 while (st.hasMoreTokens()){
                    toFile = encodeDecode( new BigInteger(st.nextToken())).toByteArray();
                    System.out.println(toFile.length + " x " + (blockSize / 8 ));
                   
                     if (toFile[ 0 ] == 0 && toFile.length != (blockSize / 8 )) {
                        temp = new byte [blockSize / 8 ];
                        offset = temp.length - toFile.length;
                         for ( int i = toFile.length - 1 ; (i <= 0 ) && ((i + offset) <= 0 ); -- i) {
                            temp[i + offset] = toFile[i];
                        }
                        toFile = temp;
                    }
                   
                     /* if (toFile.length != ((blockSize / 8) + 1)){
                        temp = new byte[(blockSize / 8) + 1];
                        System.out.println(toFile.length + " x " + temp.length);
                        for (int i = 1; i < temp.length; i++) {
                            temp[i] = toFile[i - 1];
                        }
                        toFile = temp;
                    }
                    else
                        System.out.println(toFile.length + " " + ((blockSize / 8) + 1)); */
                    os.write(toFile);
                }
            }
        }
         catch (IOException e1) {
            System.out.println( " Something went wrong " );
        }
       
         /**
         * close data streams
          */
         try {
            os.close();
            reader.close();
        }
         catch (IOException e1) {
            System.out.println( " Error closing file. " );
        }
    }
   
     /**
     * Performs <tt>base</tt>^^<tt>pow</tt> within the modular
     * domain of <tt>mod</tt>.
     *
     * @param base the base to be raised
     * @param pow the power to which the base will be raisded
     * @param mod the modular domain over which to perform this operation
     * @return <tt>base</tt>^^<tt>pow</tt> within the modular
     * domain of <tt>mod</tt>.
      */
     public BigInteger encodeDecode(BigInteger base) {
        BigInteger a = ONE;
        BigInteger s = base;
        BigInteger n = myKey;
       
         while ( ! n.equals(ZERO)) {
             if ( ! n.mod(TWO).equals(ZERO))
                a = a.multiply(s).mod(myMod);
           
            s = s.pow( 2 ).mod(myMod);
            n = n.divide(TWO);
        }
       
         return a;
    }
   
}

在这里提供两个版本的RSA算法JAVA实现的代码下载：

1. 来自于 [url]http://www.javafr.com/code.aspx?ID=27020[/url] 的RSA算法实现源代码包:
        [url]http://zeal.newmenbase.net/attachment/JavaFR_RSA_Source.rar[/url] 

2. 来自于 [url]http://www.ferrara.linux.it/Members/lucabariani/RSA/implementazioneRsa/[/url] 的实现:
       [url]http://zeal.newmenbase.net/attachment/sorgentiJava.tar.gz[/url]  - 源代码包
       [url]http://zeal.newmenbase.net/attachment/algoritmoRSA.jar[/url] - 编译好的jar包

另外关于RSA算法的php实现请参见文章:
       php下的RSA算法实现

关于使用VB实现RSA算法的源代码下载(此程序采用了psc1算法来实现快速的RSA加密):
       [url]http://zeal.newmenbase.net/attachment/vb_PSC1_RSA.rar[/url]

RSA加密的JavaScript实现: [url]http://www.ohdave.com/rsa/[/url]