Java加密技术（三）

接下来我们介绍非对称加密算法，RSA
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。
    公钥公开，私钥保密。我们用公钥加密数据，用私钥解密数据，最常用作为数字签名。
通过java代码实现如下：

import java.security.Key;
 import java.security.KeyFactory;
 import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 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 class RSACoder extends Coder {
     public static final String ALGORITHM = "RSA";
     private static final String PUBLIC_KEY = "RSAPublicKey";
     private static final String PRIVATE_KEY = "RSAPrivateKey";

     /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
     public static byte[] decrypt(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(ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

         // 对数据解密
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);

         return cipher.doFinal(data);
    }

     /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
     public static byte[] encrypt(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(ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);

         // 对数据加密
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

         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(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;
    }
}

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
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 class RSACoder extends Coder {
	public static final String ALGORITHM = "RSA";
	private static final String PUBLIC_KEY = "RSAPublicKey";
	private static final String PRIVATE_KEY = "RSAPrivateKey";

	/**
	 * 解密<br>
	 * 用私钥解密
	 * 
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] decrypt(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(ALGORITHM);
		Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

		// 对数据解密
		Cipher cipher = Cipher.getInstance(ALGORITHM);
		cipher.init(Cipher.DECRYPT_MODE, privateKey);

		return cipher.doFinal(data);
	}

	/**
	 * 加密<br>
	 * 用公钥加密
	 * 
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] encrypt(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(ALGORITHM);
		Key publicKey = keyFactory.generatePublic(x509KeySpec);

		// 对数据加密
		Cipher cipher = Cipher.getInstance(ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, publicKey);

		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(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.Test;

 import org.zlex.commons.io.IOUtils;

 import java.util.Map;

 /**
 *
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
 public class RSACoderTest {
     @Test
     public void test() throws Exception {
         String inputStr = "abc";
         byte[] data = inputStr.getBytes();

        Map<String, Object> keyMap = RSACoder.initKey();

        String publicKey = RSACoder.getPublicKey(keyMap);
        String privateKey = RSACoder.getPrivateKey(keyMap);
         System.err.println("publicKey: \n\r" + publicKey);
         System.err.println("privateKey： \n\r" + privateKey);

         byte[] encodedData = RSACoder.encrypt(data, publicKey);

         byte[] decodedData = RSACoder.decrypt(encodedData, privateKey);
         String outputStr = new String(decodedData);
         System.err.println("inputStr: " + inputStr + "\n\r" + "outputStr: "
                + outputStr);
        assertEquals(inputStr, outputStr);
    }
}

import static org.junit.Assert.*;

import org.junit.Test;

import org.zlex.commons.io.IOUtils;

import java.util.Map;

/**
 * 
 * @author 梁栋
 * @version 1.0
 * @since 1.0
 */
public class RSACoderTest {
	@Test
	public void test() throws Exception {
		String inputStr = "abc";
		byte[] data = inputStr.getBytes();

		Map<String, Object> keyMap = RSACoder.initKey();

		String publicKey = RSACoder.getPublicKey(keyMap);
		String privateKey = RSACoder.getPrivateKey(keyMap);
		System.err.println("publicKey: \n\r" + publicKey);
		System.err.println("privateKey： \n\r" + privateKey);

		byte[] encodedData = RSACoder.encrypt(data, publicKey);

		byte[] decodedData = RSACoder.decrypt(encodedData, privateKey);
		String outputStr = new String(decodedData);
		System.err.println("inputStr: " + inputStr + "\n\r" + "outputStr: "
				+ outputStr);
		assertEquals(inputStr, outputStr);
	}
}

控制台输出：

publicKey:

MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCynMFQnRG1ZwfewDxaNDvFskU8zC1R6Uxq7hk+
0eaUHU/6Yi5kYWU1LJkkw23PvTq1JJ9XfunSWP2q2HlNCGQ+802MGXh5N3tikRIcA4XIehPwTTdN
5Gzvohh39N5lOL9X/TPhMIFtRzCaVWYpz/allDlB9SlJ+/pmYo37H5cIyQIDAQAB

privateKey：
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inputStr: abc

outputStr: abc