本文是在参考文章的基础上修改的，对下面评论的问题进行一些测试和实现,同时对一些代码增加了相关的注释方便理解：
需了解的知识:
问题：
1、修改公私钥还可以成功解密？ 通过修改密钥测试，我的是会报错的
2、私钥加密公钥解密报错？ 通过对代码的修改，进行测试成功了
代码如下
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.Base64;
import java.util.HashMap;
import java.util.Map;
/**
* @创建人 QC
* @创建时间 2021-8-25
*/
public class Test {
/**
* 密钥长度 于原文长度对应 以及越长速度越慢
*/
private final static int KEY_SIZE = 1024;
/**
* 用于封装随机产生的公钥与私钥
*/
private static Map<Integer, String> keyMap = new HashMap<Integer, String>();
/**
* 随机生成密钥对
*/
public static void genKeyPair() throws NoSuchAlgorithmException {
// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
// 初始化密钥对生成器
keyPairGen.initialize(KEY_SIZE, new SecureRandom());
// 生成一个密钥对，保存在keyPair中
KeyPair keyPair = keyPairGen.generateKeyPair();
// 得到私钥
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
// 得到公钥
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
String publicKeyString = Base64.getEncoder().encodeToString(publicKey.getEncoded());
// 得到私钥字符串
String privateKeyString = Base64.getEncoder().encodeToString(privateKey.getEncoded());
// 将公钥和私钥保存到Map
//0表示公钥
keyMap.put(0, publicKeyString);
//1表示私钥
keyMap.put(1, privateKeyString);
}
/**
* RSA公钥加密
*
* @param str 加密字符串
* @param publicKey 公钥
* @return 密文
* @throws Exception 加密过程中的异常信息
*/
public static String encrypt(String str, String publicKey) throws Exception {
//base64编码的公钥, 用base64处理下主要是将字符串内的不可见字符转换成可见字符，防止不同机器处理错误
byte[] decoded = Base64.getDecoder().decode(publicKey);
RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
//RSA加密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
//这里没用像解密 new String 主要还是这个是要传输的，所以用base64编码的，防止错误
String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(str.getBytes("UTF-8")));
return outStr;
}
/**
* RSA私钥加密
*
*
* @param str 加密字符串
* @param privateKey 私钥
* @return
* @throws Exception
*/
public static String encryptByPrivate(String str,String privateKey ) throws Exception {
//base64编码公钥
byte[] decoded = Base64.getDecoder().decode(privateKey);
RSAPrivateKey rsa = (RSAPrivateKey)KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE,rsa);
String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(str.getBytes("UTF-8")));
// String outStr = new String(cipher.doFinal(decoded));
return outStr;
}
/**
* RSA私钥解密
*
* @param str 待解密字符串
* @param privateKey 私钥
* @return 明文
* @throws Exception 解密过程中的异常信息
*/
public static String decrypt(String str, String privateKey) throws Exception {
//64位解码加密后的字符串
byte[] inputByte = Base64.getDecoder().decode(str);
//base64编码的私钥
byte[] decoded = Base64.getDecoder().decode(privateKey);
RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
//RSA解密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, priKey);
//这里直接new String() , 不用传输，为了直接查看解密后的明文（base64加密后看不懂）
String outStr = new String(cipher.doFinal(inputByte));
// byte[] decode = Base64.getDecoder().decode(inputByte); base64编码后的明文
return outStr;
}
/**
*
* RSA公钥解密
*
* @param str 待解密字符串
* @param publicKey 公钥
* @return 明文
* @throws Exception
*/
public static String decryptByPublic(String str,String publicKey) throws Exception{
//获取Base64编码的待解密密文
byte[] inputByte = Base64.getDecoder().decode(str);
//获取Base64编码的公钥
byte[] decode = Base64.getDecoder().decode(publicKey);
PublicKey rsa = KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decode));
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE,rsa);
String outStr = new String(cipher.doFinal(inputByte));
return outStr;
}
public static void main(String[] args) throws Exception {
System.out.println("-------------------------------------------公钥加密，私钥解密------------------------------------------------");
long temp = System.currentTimeMillis();
//生成公钥和私钥
genKeyPair();
//加密字符串
System.out.println("公钥:" + keyMap.get(0));
System.out.println("私钥:" + keyMap.get(1));
// System.err.println(keyMap.get(0));
// String s = keyMap.get(0);
// keyMap.put(0,s.substring(0,s.length()-1));
// System.err.println(keyMap.get(0));
System.out.println("生成密钥消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");
String message = "RSA测试ABCD~!@#$";
System.out.println("原文:" + message);
temp = System.currentTimeMillis();
String messageEn = encrypt(message, keyMap.get(0));
System.out.println("密文:" + messageEn);
System.out.println("加密消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");
temp = System.currentTimeMillis();
String messageDe = decrypt(messageEn, keyMap.get(1));
System.out.println("解密:" + messageDe);
System.out.println("解密消耗时间:" + (System.currentTimeMillis() - temp) / 1000.0 + "秒");
System.out.println("-------------------------------------------私钥加密，公钥解密，签名------------------------------------------------");
long temp1 = System.currentTimeMillis();
//生成公钥和私钥
genKeyPair();
//加密字符串
System.out.println("公钥:" + keyMap.get(0));
System.out.println("私钥:" + keyMap.get(1));
// System.err.println(keyMap.get(0));
// String s = keyMap.get(0);
// keyMap.put(0,s.substring(0,s.length()-1));
// System.err.println(keyMap.get(0));
System.out.println("生成密钥消耗时间:" + (System.currentTimeMillis() - temp1) / 1000.0 + "秒");
String message1 = "RSA测试ABCD~!@#$";
System.out.println("原文:" + message1);
temp1 = System.currentTimeMillis();
String messageEn1 = encryptByPrivate(message1, keyMap.get(1));
System.out.println("密文:" + messageEn1);
System.out.println("加密消耗时间:" + (System.currentTimeMillis() - temp1) / 1000.0 + "秒");
temp1 = System.currentTimeMillis();
String messageDe1 = decryptByPublic(messageEn1, keyMap.get(0));
System.out.println("解密:" + messageDe1);
System.out.println("解密消耗时间:" + (System.currentTimeMillis() - temp1) / 1000.0 + "秒");
}
}
欢迎大家指正>.<
