java 文件加密解密

  1 package com.test;
  2 
  3 import java.io.File;
  4 import java.io.FileInputStream;
  5 import java.io.FileOutputStream;
  6 import java.io.InputStream;
  7 import java.io.OutputStream;
  8 import java.security.KeyPair;
  9 import java.security.KeyPairGenerator;
 10 import java.security.NoSuchAlgorithmException;
 11 import java.security.interfaces.RSAPrivateKey;
 12 import java.security.interfaces.RSAPublicKey;
 13 import javax.crypto.Cipher;
 14 
 15 public class RSAEncrypt {
 16 
 17     static KeyPairGenerator keyPairGen;
 18 
 19     static KeyPair keyPair;
 20 
 21     static RSAPrivateKey privateKey;
 22 
 23     static RSAPublicKey publicKey;
 24 
 25     static {
 26         try {
 27             keyPairGen = KeyPairGenerator.getInstance("RSA");
 28             keyPairGen.initialize(512);
 29             keyPair = keyPairGen.generateKeyPair();
 30             // Generate keys
 31             privateKey = (RSAPrivateKey) keyPair.getPrivate();
 32             publicKey = (RSAPublicKey) keyPair.getPublic();
 33         } catch (NoSuchAlgorithmException e) {
 34             // TODO Auto-generated catch block
 35             e.printStackTrace();
 36         }
 37     }
 38 
 39     public static void main(String[] args) {
 40         RSAEncrypt encrypt = new RSAEncrypt();
 41         File file = new File("C:\\Users\\张洋\\Desktop\\logo1.png");
 42         File newFile = new File("C:\\Users\\张洋\\Desktop\\logo已加密");
 43         encrypt.encryptFile(encrypt, file, newFile);
 44         File file1 = new File("C:\\Users\\张洋\\Desktop\\logo已加密");
 45         File newFile1 = new File("C:\\Users\\张洋\\Desktop\\logo已解密.png");
 46         encrypt.decryptFile(encrypt, file1, newFile1);
 47     }
 48 
 49     public void encryptFile(RSAEncrypt encrypt, File file, File newFile) {
 50         try {
 51             InputStream is = new FileInputStream(file);
 52             OutputStream os = new FileOutputStream(newFile);
 53 
 54             byte[] bytes = new byte[53];
 55             while (is.read(bytes) > 0) {
 56                 byte[] e = encrypt.encrypt(RSAEncrypt.publicKey, bytes);
 57                 bytes = new byte[53];
 58                 os.write(e, 0, e.length);
 59             }
 60             os.close();
 61             is.close();
 62             System.out.println("write success");
 63         } catch (Exception e) {
 64             e.printStackTrace();
 65         }
 66     }
 67 
 68     public void decryptFile(RSAEncrypt encrypt, File file, File newFile) {
 69         try {
 70             InputStream is = new FileInputStream(file);
 71             OutputStream os = new FileOutputStream(newFile);
 72             byte[] bytes1 = new byte[64];
 73             while (is.read(bytes1) > 0) {
 74                 byte[] de = encrypt.decrypt(RSAEncrypt.privateKey, bytes1);
 75                 bytes1 = new byte[64];
 76                 os.write(de, 0, de.length);
 77             }
 78             os.close();
 79             is.close();
 80             System.out.println("write success");
 81 
 82         } catch (Exception e) {
 83             e.printStackTrace();
 84         }
 85     }
 86 
 87     /** */
 88     /**
 89      * * Encrypt String. *
 90      * 
 91      * @return byte[]
 92      */
 93     protected byte[] encrypt(RSAPublicKey publicKey, byte[] obj) {
 94         if (publicKey != null) {
 95             try {
 96                 Cipher cipher = Cipher.getInstance("RSA");
 97                 cipher.init(Cipher.ENCRYPT_MODE, publicKey);
 98                 return cipher.doFinal(obj);
 99             } catch (Exception e) {
100                 e.printStackTrace();
101             }
102         }
103         return null;
104     }
105 
106     /** */
107     /**
108      * * Basic decrypt method *
109      * 
110      * @return byte[]
111      */
112     protected byte[] decrypt(RSAPrivateKey privateKey, byte[] obj) {
113         if (privateKey != null) {
114             try {
115                 Cipher cipher = Cipher.getInstance("RSA");
116                 cipher.init(Cipher.DECRYPT_MODE, privateKey);
117                 return cipher.doFinal(obj);
118             } catch (Exception e) {
119                 e.printStackTrace();
120             }
121         }
122         return null;
123     }
124 }