非对称加密算法RSA--转

RSA 
    这种算法1978年就出现了，它是第一个既能用于数据加密也能用于数字签名的算法。它易于理解和操作，也很流行。算法的名字以发明者的名字命名：Ron Rivest, AdiShamir 和Leonard Adleman。 
    这种加密算法的特点主要是密钥的变化，上文我们看到DES只有一个密钥。相当于只有一把钥匙，如果这把钥匙丢了，数据也就不安全了。RSA同时有两把钥匙，公钥与私钥。同时支持数字签名。数字签名的意义在于，对传输过来的数据进行校验。确保数据在传输工程中不被修改。 

流程分析： 

甲方构建密钥对儿，将公钥公布给乙方，将私钥保留。

甲方使用私钥加密数据，然后用私钥对加密后的数据签名，发送给乙方签名以及加密后的数据；乙方使用公钥、签名来验证待解密数据是否有效，如果有效使用公钥对数据解密。

乙方使用公钥加密数据，向甲方发送经过加密后的数据；甲方获得加密数据，通过私钥解密。

按如上步骤给出序列图，如下： 

通过java代码实现如下：Coder类见 Java加密技术（一） 

import java.security.Key; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.Signature; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec;import java.util.HashMap; import java.util.Map;import javax.crypto.Cipher;/*** RSA安全编码组件* * @author 梁栋* @version 1.0* @since 1.0*/ public abstract class RSACoder extends Coder {public static final String KEY_ALGORITHM = "RSA";public static final String SIGNATURE_ALGORITHM = "MD5withRSA";private static final String PUBLIC_KEY = "RSAPublicKey";private static final String PRIVATE_KEY = "RSAPrivateKey";/*** 用私钥对信息生成数字签名* * @param data* 加密数据* @param privateKey* 私钥* * @return* @throws Exception*/public static String sign(byte[] data, String privateKey) throws Exception {// 解密由base64编码的私钥byte[] keyBytes = decryptBASE64(privateKey);// 构造PKCS8EncodedKeySpec对象PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);// KEY_ALGORITHM 指定的加密算法KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);// 取私钥匙对象PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);// 用私钥对信息生成数字签名Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initSign(priKey);signature.update(data);return encryptBASE64(signature.sign());}/*** 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* @throws Exception* */public static boolean verify(byte[] data, String publicKey, String sign)throws Exception {// 解密由base64编码的公钥byte[] keyBytes = decryptBASE64(publicKey);// 构造X509EncodedKeySpec对象X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);// KEY_ALGORITHM 指定的加密算法KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);// 取公钥匙对象PublicKey pubKey = keyFactory.generatePublic(keySpec);Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initVerify(pubKey);signature.update(data);// 验证签名是否正常return signature.verify(decryptBASE64(sign));}/*** 解密<br>* 用私钥解密* * @param data* @param key* @return* @throws Exception*/public static byte[] decryptByPrivateKey(byte[] data, String key)throws Exception {// 对密钥解密byte[] keyBytes = decryptBASE64(key);// 取得私钥PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);// 对数据解密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, privateKey);return cipher.doFinal(data);}/*** 解密<br>* 用公钥解密* * @param data* @param key* @return* @throws Exception*/public static byte[] decryptByPublicKey(byte[] data, String key)throws Exception {// 对密钥解密byte[] keyBytes = decryptBASE64(key);// 取得公钥X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicKey = keyFactory.generatePublic(x509KeySpec);// 对数据解密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, publicKey);return cipher.doFinal(data);}/*** 加密<br>* 用公钥加密* * @param data* @param key* @return* @throws Exception*/public static byte[] encryptByPublicKey(byte[] data, String key)throws Exception {// 对公钥解密byte[] keyBytes = decryptBASE64(key);// 取得公钥X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicKey = keyFactory.generatePublic(x509KeySpec);// 对数据加密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, publicKey);return cipher.doFinal(data);}/*** 加密<br>* 用私钥加密* * @param data* @param key* @return* @throws Exception*/public static byte[] encryptByPrivateKey(byte[] data, String key)throws Exception {// 对密钥解密byte[] keyBytes = decryptBASE64(key);// 取得私钥PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);// 对数据加密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, privateKey);return cipher.doFinal(data);}/*** 取得私钥* * @param keyMap* @return* @throws Exception*/public static String getPrivateKey(Map<String, Object> keyMap)throws Exception {Key key = (Key) keyMap.get(PRIVATE_KEY);return encryptBASE64(key.getEncoded());}/*** 取得公钥* * @param keyMap* @return* @throws Exception*/public static String getPublicKey(Map<String, Object> keyMap)throws Exception {Key key = (Key) keyMap.get(PUBLIC_KEY);return encryptBASE64(key.getEncoded());}/*** 初始化密钥* * @return* @throws Exception*/public static Map<String, Object> initKey() throws Exception {KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);keyPairGen.initialize(1024);KeyPair keyPair = keyPairGen.generateKeyPair();// 公钥RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();// 私钥RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();Map<String, Object> keyMap = new HashMap<String, Object>(2);keyMap.put(PUBLIC_KEY, publicKey);keyMap.put(PRIVATE_KEY, privateKey);return keyMap;} }

再给出一个测试类： 

import static org.junit.Assert.*;import org.junit.Before; import org.junit.Test;import java.util.Map;/*** * @author 梁栋* @version 1.0* @since 1.0*/ public class RSACoderTest {private String publicKey;private String privateKey;@Beforepublic void setUp() throws Exception {Map<String, Object> keyMap = RSACoder.initKey();publicKey = RSACoder.getPublicKey(keyMap);privateKey = RSACoder.getPrivateKey(keyMap);System.err.println("公钥: \n\r" + publicKey);System.err.println("私钥： \n\r" + privateKey);}@Testpublic void test() throws Exception {System.err.println("公钥加密——私钥解密");String inputStr = "abc";byte[] data = inputStr.getBytes();byte[] encodedData = RSACoder.encryptByPublicKey(data, publicKey);byte[] decodedData = RSACoder.decryptByPrivateKey(encodedData,privateKey);String outputStr = new String(decodedData);System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);assertEquals(inputStr, outputStr);}@Testpublic void testSign() throws Exception {System.err.println("私钥加密——公钥解密");String inputStr = "sign";byte[] data = inputStr.getBytes();byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);String outputStr = new String(decodedData);System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);assertEquals(inputStr, outputStr);System.err.println("私钥签名——公钥验证签名");// 产生签名String sign = RSACoder.sign(encodedData, privateKey);System.err.println("签名:\r" + sign);// 验证签名boolean status = RSACoder.verify(encodedData, publicKey, sign);System.err.println("状态:\r" + status);assertTrue(status);}}

 

原文地址：http://snowolf.iteye.com/blog/381767

 

转载于:https://www.cnblogs.com/davidwang456/p/3925444.html

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