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java 加密算法 RSA 实现代码

 

package com.yill;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.KeyPair;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import sun.security.rsa.RSAKeyPairGenerator;

public class YillRSA
{

    /**
     * @param args
     */
    public static void main(String[] args)
    {
        generateKeyPair();
        byte[] info = "http://www.blogjava.net/yill/".getBytes();
        System.out.println("Original info is " + new String(info));
        System.out.println("encrypted info is " + new String(encode(info)));
        System.out.println("Decrypted info is "
                + new String(decode(encode(info))));
    }

    public static void generateKeyPair()
    {
        RSAKeyPairGenerator kg = new RSAKeyPairGenerator();
        kg.initialize(1024, new SecureRandom());

        KeyPair keyPair = kg.generateKeyPair();

        PrivateKey privateKey = keyPair.getPrivate();
        writeKeyToDisk("C:\\privateKey.dat", privateKey);

        PublicKey publicKey = keyPair.getPublic();
        writeKeyToDisk("C:\\publicKey.dat", publicKey);

    }

    public static byte[] encode(byte[] info)
    {
        PrivateKey privateKey = (PrivateKey) readKeyFromDisk("C:\\privateKey.dat");

        try
        {
            Cipher cipher = Cipher.getInstance("RSA");

            cipher.init(Cipher.ENCRYPT_MODE, privateKey, new SecureRandom());

            return cipher.doFinal(info);
        }
        catch (NoSuchAlgorithmException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (NoSuchPaddingException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (InvalidKeyException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IllegalBlockSizeException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (BadPaddingException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return new byte[0];
    }

    public static byte[] decode(byte[] info)
    {
        PublicKey publicKey = (PublicKey) readKeyFromDisk("C:\\publicKey.dat");

        try
        {
            Cipher cipher = Cipher.getInstance("RSA");

            cipher.init(Cipher.DECRYPT_MODE, publicKey, new SecureRandom());

            return cipher.doFinal(info);
        }
        catch (NoSuchAlgorithmException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (NoSuchPaddingException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (InvalidKeyException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IllegalBlockSizeException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (BadPaddingException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return new byte[0];
    }

    private static void writeKeyToDisk(String file, Key key)
    {
        try
        {
            ObjectOutputStream out = new ObjectOutputStream(
                    new FileOutputStream(file));

            out.writeObject(key);

        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private static Key readKeyFromDisk(String file)
    {
        try
        {
            ObjectInputStream in = new ObjectInputStream(new FileInputStream(
                    file));
            return (Key) in.readObject();
        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (ClassNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

}
posted on 2008-03-19 00:08 yill 阅读(833) 评论(0)  编辑  收藏

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