篇三：Java加密
一、加密基础知识
加密大体上可以分为“双向加密”和“单向加密”，双向加密又分为“对称加密”和“非对称加密”；
双向加密：通过算法将明文加密后形成密文，可以通过算法还原密文；
单向加密：对消息进行摘要计算，并不能通过算法还原密文；
常用单向加密：MD5、SHA
对称加密：同一个密钥（算法）可以同时用作消息的加密和解密，也称单密钥加密。
常用的对称加密：DES、IDEA、RC2、RC4、SKIPJACK、RC5、AES
非对称加密：存在公钥、私钥，公钥加密需私钥解密，私钥加密需公钥解密
常用的非对称加密：RSA、DSA
二、加密的实现
学习地址：http://zhangyiqian.iteye.com/blog/1470713
1、单向加密的实现:MD5/SHA
a、MessageDigest工厂类
学习地址：http://blog.csdn.net/hudashi/article/details/8394158
http://blog.csdn.net/ma1kong/article/details/2662997
MessageDigest 类为应用程序提供信息摘要算法的功能，如 MD5 或 SHA 算法。信息摘要是安全的单向哈希函数，它接收任意大小的数据，并输出固定长度的哈希值。
常用步骤：
1、getInstance() 初始化 MessageDigest对象，工厂类，不能new对象； 2、update()方法处理数据，在digest()方法前任何时候都可以调用reset()方法重新处理数据； 3、digest()方法执行，获取哈希值； 4、数组转换成String字符串
具体代码：java.security.MessageDigest
MessageDigest m=MessageDigest.getInstance("MD5");
//MessageDigest m=MessageDigest.getInstance("SHA");
//初始化值，也可以直接 m.digest(byte[] byte)
m.update(str.getBytes("UTF-8" ));
//计算消息摘要
byte s[ ]=m.digest( );
//处理计算结果
StringBuffer strBuffer = new StringBuffer();
for (int i = 0; i < s.length; i++) {
strBuffer.append(Integer.toHexString(s[i]));
}
String mess = strBuffer.toString();
b、commons-codec包
//MD5加密 DigestUtils.md5Hex(str); //SHA 加密 DigestUtils.shaHex(str);
2、对称、非对称加密实现：AES、DES、RSA
javax.crypto包
对称加密
package java_crypto_symmetric; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; //import java.security.Security; 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 AESdemo { //KeyGenerator 提供对称密钥生成器的功能，支持各种算法 private KeyGenerator keygen; //SecretKey 负责保存对称密钥 private SecretKey deskey; //Cipher负责完成加密或解密工作 private Cipher c; //该字节数组负责保存加密的结果 private byte[] cipherByte; public AESdemo() throws NoSuchAlgorithmException, NoSuchPaddingException{ // Security.addProvider(new com.sun.crypto.provider.SunJCE()); //实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常) keygen = KeyGenerator.getInstance("AES"); //生成密钥 deskey = keygen.generateKey(); //生成Cipher对象,指定其支持的DES算法 c = Cipher.getInstance("AES"); } /** * 对字符串加密 * * @param str * @return * @throws InvalidKeyException * @throws IllegalBlockSizeException * @throws BadPaddingException */ public byte[] Encrytor(String str) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException { // 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式 c.init(Cipher.ENCRYPT_MODE, deskey); byte[] src = str.getBytes(); // 加密，结果保存进cipherByte cipherByte = c.doFinal(src); return cipherByte; } /** * 对字符串解密 * * @param buff * @return * @throws InvalidKeyException * @throws IllegalBlockSizeException * @throws BadPaddingException */ public byte[] Decryptor(byte[] buff) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException { // 根据密钥，对Cipher对象进行初始化，DECRYPT_MODE表示加密模式 c.init(Cipher.DECRYPT_MODE, deskey); cipherByte = c.doFinal(buff); return cipherByte; } /** * @param args * @throws NoSuchPaddingException * @throws NoSuchAlgorithmException * @throws BadPaddingException * @throws IllegalBlockSizeException * @throws InvalidKeyException */ public static void main(String[] args) throws Exception { AESdemo de1 = new AESdemo(); String msg ="www.suning.com/index.jsp"; byte[] encontent = de1.Encrytor(msg); byte[] decontent = de1.Decryptor(encontent); System.out.println("明文是:" + msg); System.out.println("加密后:" + new String(encontent)); System.out.println("解密后:" + new String(decontent)); } }
非对称加密
package java_crypto_asymmetric; 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 RSAdemo { /** * 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 { RSAdemo rsa = new RSAdemo(); String msg = "www.suning.com/index.jsp"; // 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)); } }
Base64加密
//加密 <!---->String str= "abc"; // abc为要加密的字符串 byte[] b = Base64.encodeBase64(str.getBytes(), true); System.out.println(new String(b)); //解密 <!---->String str = "YWJj"; // YWJj为要解密的字符串 byte[] b = Base64.decodeBase64(str.getBytes()); System.out.println(new String(b));
import org.apache.commons.codec.binary.Base64; public class test { public static void main(String[] args) { Base64 b64 = new Base64(); String message = "测试Base64加密"; String enc = new String(b64.encode(message.getBytes())); System.out.println(enc); System.out.println(new String(b64.decode(enc))); } }
public class Base64 { private static char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 }; private Base64(){ } public static String encode(byte[] data){ StringBuffer sb = new StringBuffer(); int len = data.length; int i = 0; int b1, b2, b3; while (i < len) { b1 = data[i++] & 0xff; if (i == len) { sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[(b1 & 0x3) << 4]); sb.append("=="); break; } b2 = data[i++] & 0xff; if (i == len) { sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); sb.append(base64EncodeChars[(b2 & 0x0f) << 2]); sb.append("="); break; } b3 = data[i++] & 0xff; sb.append(base64EncodeChars[b1 >>> 2]); sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]); sb.append(base64EncodeChars[b3 & 0x3f]); } return sb.toString(); } public static byte[] decode(String str){ byte[] data = str.getBytes(); int len = data.length; ByteArrayOutputStream buf = new ByteArrayOutputStream(len); int i = 0; int b1, b2, b3, b4; while (i < len) { /* b1 */ do { b1 = base64DecodeChars[data[i++]]; } while (i < len && b1 == -1); if (b1 == -1) { break; } /* b2 */ do { b2 = base64DecodeChars[data[i++]]; } while (i < len && b2 == -1); if (b2 == -1) { break; } buf.write(((b1 << 2) | ((b2 & 0x30) >>> 4))); /* b3 */ do { b3 = data[i++]; if (b3 == 61) { return buf.toByteArray(); } b3 = base64DecodeChars[b3]; } while (i < len && b3 == -1); if (b3 == -1) { break; } buf.write((((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2))); /* b4 */ do { b4 = data[i++]; if (b4 == 61) { return buf.toByteArray(); } b4 = base64DecodeChars[b4]; } while (i < len && b4 == -1); if (b4 == -1) { break; } buf.write((((b3 & 0x03) << 6) | b4)); } return buf.toByteArray(); } public static void main(String[] args) { String message = "Base64加密测试"; String tt = encode(message.getBytes()); System.out.println(encode(message.getBytes())); System.out.println(new String(decode(tt))); String ec = new String(org.apache.commons.codec.binary.Base64.encodeBase64(message.getBytes(),true)); System.out.println(ec); System.out.println(new String(org.apache.commons.codec.binary.Base64.decodeBase64(ec))); } }
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