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Java 加解密技术系列之 RSA
import com.google.common.collect.Maps; import sun.misc.BASE64Decoder; import sun.misc.BASE64Encoder; import javax.crypto.Cipher; import java.security.*; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Map; /** * Created by xiang.li on 2015/3/3. * RSA 加解密工具类 */ public class RSA { /** * 定义加密方式 */ private final static String KEY_RSA = "RSA"; /** * 定义签名算法 */ private final static String KEY_RSA_SIGNATURE = "MD5withRSA"; /** * 定义公钥算法 */ private final static String KEY_RSA_PUBLICKEY = "RSAPublicKey"; /** * 定义私钥算法 */ private final static String KEY_RSA_PRIVATEKEY = "RSAPrivateKey"; /** * 初始化密钥 * @return */ public static Map<String, Object> init() { Map<String, Object> map = null; try { KeyPairGenerator generator = KeyPairGenerator.getInstance(KEY_RSA); generator.initialize(1024); KeyPair keyPair = generator.generateKeyPair(); // 公钥 RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 私钥 RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 将密钥封装为map map = Maps.newHashMap(); map.put(KEY_RSA_PUBLICKEY, publicKey); map.put(KEY_RSA_PRIVATEKEY, privateKey); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return map; } /** * 用私钥对信息生成数字签名 * @param data 加密数据 * @param privateKey 私钥 * @return */ public static String sign(byte[] data, String privateKey) { String str = ""; try { // 解密由base64编码的私钥 byte[] bytes = decryptBase64(privateKey); // 构造PKCS8EncodedKeySpec对象 PKCS8EncodedKeySpec pkcs = new PKCS8EncodedKeySpec(bytes); // 指定的加密算法 KeyFactory factory = KeyFactory.getInstance(KEY_RSA); // 取私钥对象 PrivateKey key = factory.generatePrivate(pkcs); // 用私钥对信息生成数字签名 Signature signature = Signature.getInstance(KEY_RSA_SIGNATURE); signature.initSign(key); signature.update(data); str = encryptBase64(signature.sign()); } catch (Exception e) { e.printStackTrace(); } return str; } /** * 校验数字签名 * @param data 加密数据 * @param publicKey 公钥 * @param sign 数字签名 * @return 校验成功返回true，失败返回false */ public static boolean verify(byte[] data, String publicKey, String sign) { boolean flag = false; try { // 解密由base64编码的公钥 byte[] bytes = decryptBase64(publicKey); // 构造X509EncodedKeySpec对象 X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes); // 指定的加密算法 KeyFactory factory = KeyFactory.getInstance(KEY_RSA); // 取公钥对象 PublicKey key = factory.generatePublic(keySpec); // 用公钥验证数字签名 Signature signature = Signature.getInstance(KEY_RSA_SIGNATURE); signature.initVerify(key); signature.update(data); flag = signature.verify(decryptBase64(sign)); } catch (Exception e) { e.printStackTrace(); } return flag; } /** * 私钥解密 * @param data 加密数据 * @param key 私钥 * @return */ public static byte[] decryptByPrivateKey(byte[] data, String key) { byte[] result = null; try { // 对私钥解密 byte[] bytes = decryptBase64(key); // 取得私钥 PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(bytes); KeyFactory factory = KeyFactory.getInstance(KEY_RSA); PrivateKey privateKey = factory.generatePrivate(keySpec); // 对数据解密 Cipher cipher = Cipher.getInstance(factory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, privateKey); result = cipher.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return result; } /** * 私钥解密 * @param data 加密数据 * @param key 公钥 * @return */ public static byte[] decryptByPublicKey(byte[] data, String key) { byte[] result = null; try { // 对公钥解密 byte[] bytes = decryptBase64(key); // 取得公钥 X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes); KeyFactory factory = KeyFactory.getInstance(KEY_RSA); PublicKey publicKey = factory.generatePublic(keySpec); // 对数据解密 Cipher cipher = Cipher.getInstance(factory.getAlgorithm()); cipher.init(Cipher.DECRYPT_MODE, publicKey); result = cipher.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return result; } /** * 公钥加密 * @param data 待加密数据 * @param key 公钥 * @return */ public static byte[] encryptByPublicKey(byte[] data, String key) { byte[] result = null; try { byte[] bytes = decryptBase64(key); // 取得公钥 X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes); KeyFactory factory = KeyFactory.getInstance(KEY_RSA); PublicKey publicKey = factory.generatePublic(keySpec); // 对数据加密 Cipher cipher = Cipher.getInstance(factory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, publicKey); result = cipher.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return result; } /** * 私钥加密 * @param data 待加密数据 * @param key 私钥 * @return */ public static byte[] encryptByPrivateKey(byte[] data, String key) { byte[] result = null; try { byte[] bytes = decryptBase64(key); // 取得私钥 PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(bytes); KeyFactory factory = KeyFactory.getInstance(KEY_RSA); PrivateKey privateKey = factory.generatePrivate(keySpec); // 对数据加密 Cipher cipher = Cipher.getInstance(factory.getAlgorithm()); cipher.init(Cipher.ENCRYPT_MODE, privateKey); result = cipher.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return result; } /** * 获取公钥 * @param map * @return */ public static String getPublicKey(Map<String, Object> map) { String str = ""; try { Key key = (Key) map.get(KEY_RSA_PUBLICKEY); str = encryptBase64(key.getEncoded()); } catch (Exception e) { e.printStackTrace(); } return str; } /** * 获取私钥 * @param map * @return */ public static String getPrivateKey(Map<String, Object> map) { String str = ""; try { Key key = (Key) map.get(KEY_RSA_PRIVATEKEY); str = encryptBase64(key.getEncoded()); } catch (Exception e) { e.printStackTrace(); } return str; } /** * BASE64 解密 * @param key 需要解密的字符串 * @return 字节数组 * @throws Exception */ public static byte[] decryptBase64(String key) throws Exception { return (new BASE64Decoder()).decodeBuffer(key); } /** * BASE64 加密 * @param key 需要加密的字节数组 * @return 字符串 * @throws Exception */ public static String encryptBase64(byte[] key) throws Exception { return (new BASE64Encoder()).encodeBuffer(key); } /** * 测试方法 * @param args */ public static void main(String[] args) { String privateKey = ""; String publicKey = ""; // 生成公钥私钥 Map<String, Object> map = init(); publicKey = getPublicKey(map); privateKey = getPrivateKey(map); System.out.println("公钥: \n\r" + publicKey); System.out.println("私钥： \n\r" + privateKey); System.out.println("公钥加密--------私钥解密"); String word = "你好，世界！"; byte[] encWord = encryptByPublicKey(word.getBytes(), publicKey); String decWord = new String(decryptByPrivateKey(encWord, privateKey)); System.out.println("加密前: " + word + "\n\r" + "解密后: " + decWord); System.out.println("私钥加密--------公钥解密"); String english = "Hello, World!"; byte[] encEnglish = encryptByPrivateKey(english.getBytes(), privateKey); String decEnglish = new String(decryptByPublicKey(encEnglish, publicKey)); System.out.println("加密前: " + english + "\n\r" + "解密后: " + decEnglish); System.out.println("私钥签名——公钥验证签名"); // 产生签名 String sign = sign(encEnglish, privateKey); System.out.println("签名:\r" + sign); // 验证签名 boolean status = verify(encEnglish, publicKey, sign); System.out.println("状态:\r" + status); } }
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原文地址：http://www.cnblogs.com/crazylqy/p/5178198.html
