java RSA使用

java Rsa 加解密示例

2010-09-19 16:56

Rsa是非对称算法，他可以产生密钥对，可以用公钥加密，私钥解密，或者私钥加密，公钥解密，最大程度的保障安全性，也可以用私钥签名，公钥验证签名的正确性，防止拥有私钥的人抵赖。下面展示加解密算法和RSA签名验证。 产生密钥对的类： /** * */ package com.spell.rsa; import java.io.FileOutputStream; import java.io.ObjectOutputStream; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.SecureRandom; /** * 产生公钥和私钥对，并且保存在文件中，公钥 pk.dat，私钥 sk.dat * * @author Administrator * */ public class KeyGen { /** * * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // 加密的种子信息 String keyInfo = "ASDFSDFNUGD__TYTY"; KeyGen kg = new KeyGen(); kg.genKeys(keyInfo); } /** * 根据keyInfo产生公钥和私钥，并且保存到pk.dat和sk.dat文件中 * * @param keyInfo * @throws Exception */ public void genKeys(String keyInfo) throws Exception { KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA"); SecureRandom random = new SecureRandom(); random.setSeed(keyInfo.getBytes()); // 初始加密，长度为512，必须是大于512才可以的 keygen.initialize(512, random); // 取得密钥对 KeyPair kp = keygen.generateKeyPair(); // 取得公钥 PublicKey publicKey = kp.getPublic(); System.out.println(publicKey); saveFile(publicKey, "pk.dat"); // 取得私钥 PrivateKey privateKey = kp.getPrivate(); saveFile(privateKey, "sk.dat"); } /** * 保存对象到文件 * * @param obj * @param fileName * @throws Exception */ private void saveFile(Object obj, String fileName) throws Exception { ObjectOutputStream output = new ObjectOutputStream( new FileOutputStream(fileName)); output.writeObject(obj); output.close(); } } 利用公钥加密，私钥解密： package com.spell.rsa; import java.io.FileInputStream; import java.io.ObjectInputStream; import java.security.Key; import java.security.PrivateKey; import java.security.PublicKey; import java.security.Signature; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.Cipher; /** * RSA加解密,RSA签名、签名验证类 * * @author Administrator * */ public class RsaMessage { public static void main(String[] args) throws Exception { String str = "hello,有中文的情况"; System.out.println("原文：" + str); RsaMessage rsa = new RsaMessage(); RSAPrivateKey privateKey = (RSAPrivateKey) rsa.readFromFile("sk.dat"); RSAPublicKey publickKey = (RSAPublicKey) rsa.readFromFile("pk.dat"); byte[] encbyte = rsa.encrypt(str, privateKey); System.out.println("私钥加密后："); String encStr = toHexString(encbyte); System.out.println(encStr); byte[] signBytes = rsa.sign(str, privateKey); System.out.println("签名值："); String signStr = toHexString(signBytes); System.out.println(signStr); byte[] decByte = rsa.decrypt(encStr, publickKey); System.out.println("公钥解密后："); String decStr = new String(decByte); System.out.println(decStr); if (rsa.verifySign(str, signStr, publickKey)) { System.out.println("rsa sign check success"); } else { System.out.println("rsa sign check failure"); } } /** * 加密,key可以是公钥，也可以是私钥 * * @param message * @return * @throws Exception */ public byte[] encrypt(String message, Key key) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, key); return cipher.doFinal(message.getBytes()); } /** * 解密，key可以是公钥，也可以是私钥，如果是公钥加密就用私钥解密，反之亦然 * * @param message * @return * @throws Exception */ public byte[] decrypt(String message, Key key) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, key); return cipher.doFinal(toBytes(message)); } /** * 用私钥签名 * * @param message * @param key * @return * @throws Exception */ public byte[] sign(String message, PrivateKey key) throws Exception { Signature signetcheck = Signature.getInstance("MD5withRSA"); signetcheck.initSign(key); signetcheck.update(message.getBytes("ISO-8859-1")); return signetcheck.sign(); } /** * 用公钥验证签名的正确性 * * @param message * @param signStr * @return * @throws Exception */ public boolean verifySign(String message, String signStr, PublicKey key) throws Exception { if (message == null || signStr == null || key == null) { return false; } Signature signetcheck = Signature.getInstance("MD5withRSA"); signetcheck.initVerify(key); signetcheck.update(message.getBytes("ISO-8859-1")); return signetcheck.verify(toBytes(signStr)); } /** * 从文件读取object * * @param fileName * @return * @throws Exception */ private Object readFromFile(String fileName) throws Exception { ObjectInputStream input = new ObjectInputStream(new FileInputStream( fileName)); Object obj = input.readObject(); input.close(); return obj; } public static String toHexString(byte[] b) { StringBuilder sb = new StringBuilder(b.length * 2); for (int i = 0; i < b.length; i++) { sb.append(HEXCHAR[(b[i] & 0xf0) >>> 4]); sb.append(HEXCHAR[b[i] & 0x0f]); } return sb.toString(); } public static final byte[] toBytes(String s) { byte[] bytes; bytes = new byte[s.length() / 2]; for (int i = 0; i < bytes.length; i++) { bytes[i] = (byte) Integer.parseInt(s.substring(2 * i, 2 * i + 2), 16); } return bytes; } private static char[] HEXCHAR = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; }