Java RSA加密算法生成公钥和私钥

目前为止，RSA是应用最多的公钥加密算法，能够抵抗已知的绝大多数密码攻击，已被ISO推荐为公钥数据加密标准。

RSA算法中，每个通信主体都有两个钥匙，一个公钥（Public Key）用来对数据进行加密； 一个私钥（Private Key）用来对数据进行解密。 

下面来看下Java中是如何使用KeyPairGenerator生成keyMap 并从中解析出PublickKey和PrivateKey的。

编写生成key map寒暑 initKey, 如图

public static Map<String, Object> initKey() throws Exception {
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		keyPairGen.initialize(1024);
		KeyPair keyPair = keyPairGen.generateKeyPair();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		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;

	}

返回相应的公钥私钥：

public static String getPublicKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		byte[] publicKey = key.getEncoded();
		return encryptBASE64(key.getEncoded());
	}

	public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		byte[] privateKey = key.getEncoded();
		return encryptBASE64(key.getEncoded());
	}

	public static byte[] decryptBASE64(String key) throws Exception {
		return (new BASE64Decoder()).decodeBuffer(key);
	}

	public static String encryptBASE64(byte[] key) throws Exception {
		return (new BASE64Encoder()).encodeBuffer(key);
	}

完整代码：

import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;
import java.util.Map;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

@SuppressWarnings("unused")
public class RSATest {
	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";
	
	public static String getPublicKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		byte[] publicKey = key.getEncoded();
		return encryptBASE64(key.getEncoded());
	}

	public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		byte[] privateKey = key.getEncoded();
		return encryptBASE64(key.getEncoded());
	}

	public static byte[] decryptBASE64(String key) throws Exception {
		return (new BASE64Decoder()).decodeBuffer(key);
	}

	public static String encryptBASE64(byte[] key) throws Exception {
		return (new BASE64Encoder()).encodeBuffer(key);
	}

	public static Map<String, Object> initKey() throws Exception {
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		keyPairGen.initialize(1024);
		KeyPair keyPair = keyPairGen.generateKeyPair();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		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;

	}
	
	public static void main(String[] args) {
		Map<String, Object> keyMap;
		try {
			keyMap = initKey();
			String publicKey = getPublicKey(keyMap);
			System.out.println(publicKey);
			String privateKey = getPrivateKey(keyMap);
			System.out.println(privateKey);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

运行结果如图：