java实现文件加密解密

import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.Scanner;import javax.crypto.Cipher;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.DESKeySpec;import javax.swing.JFileChooser;/** * 文件名：fileencrypter.java jdk：1.40以上 说明：文件加密 加密方法：三重des加密 * 加密过程：对选中的文件加密后在同文件夹下生成一个增加了".tdes" 扩展名的加密文件 解密过程：对选中的加密文件（必须有".tdes"扩展名）进行解密 */public class fileencrypter {public static void main(String args[]) {fileencrypter da = new fileencrypter();Scanner scan = new Scanner(System.in);String pass = scan.next();String pass1 = pass.substring(0, 2);String pass2 = pass.substring(2, 4);String pass3 = pass.substring(4);System.out.println(pass1);System.out.println(pass2);System.out.println(pass3);String name = scan.next();if (scan.next().equals("en"))da.encrypt(new File(name), da.md5s(pass1) + da.md5s(pass2)+ da.md5s(pass3));elseda.decrypt(new File(name), da.md5s(pass1) + da.md5s(pass2)+ da.md5s(pass3));}/** * 加密函数 输入： 要加密的文件，密码（由0-F组成，共48个字符，表示3个8位的密码）如： * AD67EA2F3BE6E5ADD368DFE03120B5DF92A8FD8FEC2F0746 其中： AD67EA2F3BE6E5AD * DES密码一 D368DFE03120B5DF DES密码二 92A8FD8FEC2F0746 DES密码三 输出： * 对输入的文件加密后，保存到同一文件夹下增加了".tdes"扩展名的文件中。 */private void encrypt(File fileIn, String sKey) {try {if (sKey.length() == 48) {byte[] bytK1 = getKeyByStr(sKey.substring(0, 16));byte[] bytK2 = getKeyByStr(sKey.substring(16, 32));byte[] bytK3 = getKeyByStr(sKey.substring(32, 48));FileInputStream fis = new FileInputStream(fileIn);byte[] bytIn = new byte[(int) fileIn.length()];for (int i = 0; i < fileIn.length(); i++) {bytIn[i] = (byte) fis.read();}// 加密byte[] bytOut = encryptByDES(encryptByDES(encryptByDES(bytIn,bytK1), bytK2), bytK3);String fileOut = "en_"+fileIn.getPath();FileOutputStream fos = new FileOutputStream(fileOut);for (int i = 0; i < bytOut.length; i++) {fos.write((int) bytOut[i]);}fos.close();} else;} catch (Exception e) {e.printStackTrace();}}/** * 解密函数 输入： 要解密的文件，密码（由0-F组成，共48个字符，表示3个8位的密码）如： * AD67EA2F3BE6E5ADD368DFE03120B5DF92A8FD8FEC2F0746 其中： AD67EA2F3BE6E5AD * DES密码一 D368DFE03120B5DF DES密码二 92A8FD8FEC2F0746 DES密码三 输出： * 对输入的文件解密后，保存到用户指定的文件中。 */private void decrypt(File fileIn, String sKey) {try {if (sKey.length() == 48) {String strPath = fileIn.getPath();strPath = strPath.substring(0, strPath.length() - 5);JFileChooser chooser = new JFileChooser();chooser.setCurrentDirectory(new File("."));chooser.setSelectedFile(new File(strPath));byte[] bytK1 = getKeyByStr(sKey.substring(0, 16));byte[] bytK2 = getKeyByStr(sKey.substring(16, 32));byte[] bytK3 = getKeyByStr(sKey.substring(32, 48));FileInputStream fis = new FileInputStream(fileIn);byte[] bytIn = new byte[(int) fileIn.length()];for (int i = 0; i < fileIn.length(); i++) {bytIn[i] = (byte) fis.read();}// 解密byte[] bytOut = decryptByDES(decryptByDES(decryptByDES(bytIn,bytK3), bytK2), bytK1);File fileOut = chooser.getSelectedFile();fileOut.createNewFile();FileOutputStream fos = new FileOutputStream(fileOut);for (int i = 0; i < bytOut.length; i++) {fos.write((int) bytOut[i]);}fos.close();}} catch (Exception e) {System.out.println("解密错误！");}}/** * 用DES方法加密输入的字节 bytKey需为8字节长，是加密的密码 */private byte[] encryptByDES(byte[] bytP, byte[] bytKey) throws Exception {DESKeySpec desKS = new DESKeySpec(bytKey);SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");SecretKey sk = skf.generateSecret(desKS);Cipher cip = Cipher.getInstance("DES");cip.init(Cipher.ENCRYPT_MODE, sk);return cip.doFinal(bytP);}/** * 用DES方法解密输入的字节 bytKey需为8字节长，是解密的密码 */private byte[] decryptByDES(byte[] bytE, byte[] bytKey) throws Exception {DESKeySpec desKS = new DESKeySpec(bytKey);SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");SecretKey sk = skf.generateSecret(desKS);Cipher cip = Cipher.getInstance("DES");cip.init(Cipher.DECRYPT_MODE, sk);return cip.doFinal(bytE);}/** * 输入密码的字符形式，返回字节数组形式。 如输入字符串：AD67EA2F3BE6E5AD * 返回字节数组：{173,103,234,47,59,230,229,173} */private byte[] getKeyByStr(String str) {byte[] bRet = new byte[str.length() / 2];for (int i = 0; i < str.length() / 2; i++) {Integer itg = new Integer(16 * getChrInt(str.charAt(2 * i))+ getChrInt(str.charAt(2 * i + 1)));bRet[i] = itg.byteValue();}return bRet;}/** * 计算一个16进制字符的10进制值 输入：0-F */private int getChrInt(char chr) {int iRet = 0;if (chr == "0".charAt(0))iRet = 0;if (chr == "1".charAt(0))iRet = 1;if (chr == "2".charAt(0))iRet = 2;if (chr == "3".charAt(0))iRet = 3;if (chr == "4".charAt(0))iRet = 4;if (chr == "5".charAt(0))iRet = 5;if (chr == "6".charAt(0))iRet = 6;if (chr == "7".charAt(0))iRet = 7;if (chr == "8".charAt(0))iRet = 8;if (chr == "9".charAt(0))iRet = 9;if (chr == "A".charAt(0))iRet = 10;if (chr == "B".charAt(0))iRet = 11;if (chr == "C".charAt(0))iRet = 12;if (chr == "D".charAt(0))iRet = 13;if (chr == "E".charAt(0))iRet = 14;if (chr == "F".charAt(0))iRet = 15;return iRet;}public String md5s(String plainText) {String str = null;try {MessageDigest md = MessageDigest.getInstance("MD5");md.update(plainText.getBytes());byte b[] = md.digest();int i;StringBuffer buf = new StringBuffer("");for (int offset = 0; offset < b.length; offset++) {i = b[offset];if (i < 0)i += 256;if (i < 16)buf.append("0");buf.append(Integer.toHexString(i));}// System.out.println("result: " + buf.toString());// 32位的加密// System.out.println("result: " + buf.toString().substring(8,// 24));// 16位的加密str = buf.toString().substring(8, 24);} catch (NoSuchAlgorithmException e) {// TODO Auto-generated catch blocke.printStackTrace();}return str;}}

java实现文件加密解密