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加密有单向加密和双向加密之分,也叫对称加密和非对称加密,双向加密就是把数据加密后,还可以解密成原来的数据,但是需要使用到密钥,而且必须是同一个密钥.才可以解密成原来的数据.一开始我也不知道,密钥是使用系统生成的密钥,加密和解密分开操作的时候,加密过后,数据就解密不出来了.java实现加密的方法有DES,AES,等这些对称加密.单向加密从严格的意义来讲不算加密.只是实现了一定的算法,但是不可以逆转.MD5加密就是一个单向非对称加密的技术.直接上代码
package com.chen; import java.security.InvalidKeyException; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; public class Chen { // 密钥生成器 private KeyGenerator kg = null; // 密钥 private SecretKey key = null; // 进行加密和解密 private Cipher cip = null; public Chen() throws Exception{ kg = KeyGenerator.getInstance("DES"); key = kg.generateKey(); cip = Cipher.getInstance("DES"); } public byte[] encrypt(byte[] s) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ // 初始化 cip.init(Cipher.ENCRYPT_MODE, key); // 加密 return cip.doFinal(s); } public byte[] decrypt(byte[] b) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ // 初始化 cip.init(Cipher.DECRYPT_MODE, key); // 解密 return cip.doFinal(b); } public static void main(String[] args) { try { Chen chen = new Chen(); String str = "aba萨芬斯蒂芬"; // 加密 byte[] temp = chen.encrypt(str.getBytes()); // 解密 byte[] flag = chen.decrypt(temp); System.out.println("明文 : " + str); System.out.println("加密后的数据 : " + new String(temp)); System.out.println("解密后的数据 : " + new String(flag)); } catch (Exception e) { e.printStackTrace(); } } }
AES加密和解密的代码
package crypt; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.KeyGenerator; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; public class AEScrypt { // key生成器 private KeyGenerator kg; // 密钥 private SecretKey key; // 加密解密类 private Cipher cipher; public AEScrypt() throws NoSuchAlgorithmException, NoSuchPaddingException{ kg = KeyGenerator.getInstance("AES"); System.out.println(kg.getProvider().getName()); key = kg.generateKey(); cipher = Cipher.getInstance("AES"); System.out.println(cipher.getProvider()); } public byte[] encrypt(byte[] b) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ // 初始化 cipher.init(Cipher.ENCRYPT_MODE, key); return cipher.doFinal(b); } public byte[] decrypt(byte[] b) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ // 初始化 cipher.init(Cipher.DECRYPT_MODE, key); // 解密 return cipher.doFinal(b); } public static void main(String[] args) { try { AEScrypt aes = new AEScrypt(); String s = "safasf的送饭饭2342(&((*"; byte[] temp = aes.encrypt(s.getBytes()); byte[] flag = aes.decrypt(temp); System.out.println("明文 : " + s); System.out.println("加密 : " + new String(temp)); System.out.println("解密 : " + new String(flag)); } catch (Exception e) { e.printStackTrace(); } } }
非对称RSA,有连个密钥,一个公开密钥,一个私有密钥,通过其中一个密钥加密,在通过其他一个密钥解密
package crypt; import java.security.InvalidKeyException; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; public class RSAcrypt { /** * 加密 * @param publicKey * @param srcBytes * @return * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws InvalidKeyException * @throws IllegalBlockSizeException * @throws BadPaddingException */ protected byte[] encrypt(RSAPublicKey publicKey,byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ if(publicKey!=null){ //Cipher负责完成加密或解密工作，基于RSA Cipher cipher = Cipher.getInstance("RSA"); //根据公钥，对Cipher对象进行初始化 cipher.init(Cipher.ENCRYPT_MODE, publicKey); byte[] resultBytes = cipher.doFinal(srcBytes); return resultBytes; } return null; } /** * 解密 * @param privateKey * @param srcBytes * @return * @throws NoSuchAlgorithmException * @throws NoSuchPaddingException * @throws InvalidKeyException * @throws IllegalBlockSizeException * @throws BadPaddingException */ protected byte[] decrypt(RSAPrivateKey privateKey,byte[] srcBytes) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{ if(privateKey!=null){ //Cipher负责完成加密或解密工作，基于RSA Cipher cipher = Cipher.getInstance("RSA"); //根据公钥，对Cipher对象进行初始化 cipher.init(Cipher.DECRYPT_MODE, privateKey); byte[] resultBytes = cipher.doFinal(srcBytes); return resultBytes; } return null; } /** * @param args * @throws NoSuchAlgorithmException * @throws BadPaddingException * @throws IllegalBlockSizeException * @throws NoSuchPaddingException * @throws InvalidKeyException */ public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException { RSAcrypt rsa = new RSAcrypt(); String msg = "郭XX-精品相声"; //KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA"); //初始化密钥对生成器，密钥大小为1024位 keyPairGen.initialize(1024); //生成一个密钥对，保存在keyPair中 KeyPair keyPair = keyPairGen.generateKeyPair(); //得到私钥 RSAPrivateKey privateKey = (RSAPrivateKey)keyPair.getPrivate(); //得到公钥 RSAPublicKey publicKey = (RSAPublicKey)keyPair.getPublic(); //用公钥加密 byte[] srcBytes = msg.getBytes(); byte[] resultBytes = rsa.encrypt(publicKey, srcBytes); //用私钥解密 byte[] decBytes = rsa.decrypt(privateKey, resultBytes); System.out.println("明文是:" + msg); System.out.println("加密后是:" + new String(resultBytes)); System.out.println("解密后是:" + new String(decBytes)); } }
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原文地址：http://www.cnblogs.com/homesea/p/4748624.html
