Java RSA非对称加密算法实现

package com.rsa;

import org.apache.commons.codec.binary.Base64;

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.HashMap;
import java.util.Map;

/**
* 非对称加密算法RSA算法组件
* 非对称算法一般是用来传送对称加密算法的密钥来使用的，相对于DH算法，RSA算法只需要一方构造密钥，不需要
* 大费周章的构造各自本地的密钥对了。DH算法只能算法非对称算法的底层实现。而RSA算法算法实现起来较为简单
*
* @author kongqz
*/
public class RSACoder {
//非对称密钥算法
public static final String KEY_ALGORITHM = "RSA";

/**
* 密钥长度，DH算法的默认密钥长度是1024
* 密钥长度必须是64的倍数，在512到65536位之间
*/
private static final int KEY_SIZE = 512;
//公钥
private static final String PUBLIC_KEY = "RSAPublicKey";

//私钥
private static final String PRIVATE_KEY = "RSAPrivateKey";

/**
* 初始化密钥对
*
* @return Map 甲方密钥的Map
*/
public static Map<String, Object> initKey() throws Exception {
//实例化密钥生成器
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
//初始化密钥生成器
keyPairGenerator.initialize(KEY_SIZE);
//生成密钥对
KeyPair keyPair = keyPairGenerator.generateKeyPair();
//甲方公钥
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
//甲方私钥
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
//将密钥存储在map中
Map<String, Object> keyMap = new HashMap<String, Object>();
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;

}

/**
* 私钥加密
*
* @param data 待加密数据
* @param key 密钥
* @return byte[] 加密数据
*/
public static byte[] encryptByPrivateKey(byte[] data, byte[] key) throws Exception {

//取得私钥
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
//生成私钥
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
//数据加密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(data);
}

/**
* 公钥加密
*
* @param data 待加密数据
* @param key 密钥
* @return byte[] 加密数据
*/
public static byte[] encryptByPublicKey(byte[] data, byte[] key) throws Exception {

//实例化密钥工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
//初始化公钥
//密钥材料转换
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
//产生公钥
PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);

//数据加密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
return cipher.doFinal(data);
}

/**
* 私钥解密
*
* @param data 待解密数据
* @param key 密钥
* @return byte[] 解密数据
*/
public static byte[] decryptByPrivateKey(byte[] data, byte[] key) throws Exception {
//取得私钥
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
//生成私钥
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
//数据解密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(data);
}

/**
* 公钥解密
*
* @param data 待解密数据
* @param key 密钥
* @return byte[] 解密数据
*/
public static byte[] decryptByPublicKey(byte[] data, byte[] key) throws Exception {

//实例化密钥工厂
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
//初始化公钥
//密钥材料转换
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
//产生公钥
PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
//数据解密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, pubKey);
return cipher.doFinal(data);
}

/**
* 取得私钥
*
* @param keyMap 密钥map
* @return byte[] 私钥
*/
public static byte[] getPrivateKey(Map<String, Object> keyMap) {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return key.getEncoded();
}

/**
* 取得公钥
*
* @param keyMap 密钥map
* @return byte[] 公钥
*/
public static byte[] getPublicKey(Map<String, Object> keyMap) throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return key.getEncoded();
}

/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
//初始化密钥
//生成密钥对
Map<String, Object> keyMap = RSACoder.initKey();
//公钥
byte[] publicKey = RSACoder.getPublicKey(keyMap);

//私钥
byte[] privateKey = RSACoder.getPrivateKey(keyMap);
System.out.println("公钥：/n" + Base64.encodeBase64String(publicKey));
System.out.println("私钥：/n" + Base64.encodeBase64String(privateKey));

System.out.println("================密钥对构造完毕,甲方将公钥公布给乙方，开始进行加密数据的传输=============");
String str = "RSA密码交换算法";
System.out.println("/n===========甲方向乙方发送加密数据==============");
System.out.println("原文:" + str);
//甲方进行数据的加密
byte[] code1 = RSACoder.encryptByPrivateKey(str.getBytes(), privateKey);
System.out.println("加密后的数据：" + Base64.encodeBase64String(code1));
System.out.println("===========乙方使用甲方提供的公钥对数据进行解密==============");
//乙方进行数据的解密
byte[] decode1 = RSACoder.decryptByPublicKey(code1, publicKey);
System.out.println("乙方解密后的数据：" + new String(decode1) + "/n/n");

System.out.println("===========反向进行操作，乙方向甲方发送数据==============/n/n");

str = "乙方向甲方发送数据RSA算法";

System.out.println("原文:" + str);

//乙方使用公钥对数据进行加密
byte[] code2 = RSACoder.encryptByPublicKey(str.getBytes(), publicKey);
System.out.println("===========乙方使用公钥对数据进行加密==============");
System.out.println("加密后的数据：" + Base64.encodeBase64String(code2));

System.out.println("=============乙方将数据传送给甲方======================");
System.out.println("===========甲方使用私钥对数据进行解密==============");

//甲方使用私钥对数据进行解密
byte[] decode2 = RSACoder.decryptByPrivateKey(code2, privateKey);

System.out.println("甲方解密后的数据：" + new String(decode2));
}
}

转自:https://www.cnblogs.com/frank-quan/p/7073457.html