Java RSA加密算法生成公钥和私钥

摘要: 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：