[Herramientas de Java] Cifrado asimétrico mediante el algoritmo RSA, serialización, guardado, procesamiento, clave pública, clave privada, cifrado y herramientas de descifrado

La siguiente serialización de Java generará la clave pública y la clave privada en los archivos PublicKey, PrivateKey y las guardará. El cifrado y el descifrado deben deserializar el archivo en un flujo de bytes de Java y luego realizar el procesamiento correspondiente.

• Dado que el texto cifrado está en forma de código de bytes, si queremos guardar o transmitir como una cadena, podemos usarBase64编码算法

import javax.crypto.Cipher;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

/**
 * 使用java的序列化保存处理公钥私钥加解密
 */
public class RSASerializationUtil {
    
    
    /**
     * 指定加密算法为RSA
     */
    private static final String ALGORITHM = "RSA";
    /*指定加密模式和填充方式*/
    private static final String ALGORITHM_MODEL = "RSA/ECB/PKCS1Padding";
    /**指定key的大小，一般为1024，越大安全性越高*/
    private static final  int KEYSIZE = 1024;
    /**指定公钥存放文件*/
    private static final String PUBLIC_KEY_FILE = "PublicKey";
    /**指定私钥存放文件*/
    private static  final String PRIVATE_KEY_FILE = "PrivateKey";




    /**
     * 从base64编码的公钥恢复公钥
     * @param key_base64
     * @return
     * @throws Exception
     */
    public PublicKey getPulbickey(String key_base64) throws Exception{
    
    
        byte[] pb =  Base64.getDecoder().decode(key_base64);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(pb);
        KeyFactory  keyfactory = KeyFactory.getInstance(ALGORITHM);
        return keyfactory.generatePublic(keySpec);
    }

    /**
     * 从base64编码的私钥恢复私钥
     * @param key_base64
     * @return
     * @throws Exception
     */
    public PrivateKey getPrivatekey(String key_base64) throws Exception{
    
    
        byte[] pb =  Base64.getDecoder().decode(key_base64);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pb);
        KeyFactory  keyfactory = KeyFactory.getInstance(ALGORITHM);
        return keyfactory.generatePrivate(keySpec);
    }

    //从base64编码的特征值(N,e)恢复公钥
    public static PublicKey getPulbickey(String N_Str,String e_Str) throws Exception{
    
    
        BigInteger N = new BigInteger(1, Base64.getDecoder().decode(N_Str.getBytes()));
        BigInteger e = new BigInteger(1, Base64.getDecoder().decode(e_Str.getBytes()));
        KeyFactory kf = KeyFactory.getInstance(ALGORITHM);
        RSAPublicKeySpec ps = new RSAPublicKeySpec(N, e);
        PublicKey pkey = kf.generatePublic(ps);
        return pkey;
    }
    //从base64编码的特征值（N,d）恢复私钥
    public static PrivateKey getPrivatekey(String N_Str,String d_Str) throws Exception{
    
    
        BigInteger N = new BigInteger(1,  Base64.getDecoder().decode(N_Str.getBytes()));
        BigInteger d = new BigInteger(1,  Base64.getDecoder().decode(d_Str.getBytes()));
        KeyFactory kf = KeyFactory.getInstance(ALGORITHM);
        RSAPrivateKeySpec ps = new RSAPrivateKeySpec(N, d);
        PrivateKey pkey = kf.generatePrivate(ps);
        return pkey;
    }

    /**
     * 提取特征值保存，以base64编码密钥
     *
     * @return
     * @throws Exception
     */
    public static Map<String ,String> generateKeyPair2() throws Exception{
    
    
        SecureRandom sr = new SecureRandom();
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
        kpg.initialize(1024, sr);
        KeyPair kp = kpg.generateKeyPair();
        Key publicKey = kp.getPublic();
        Key privateKey = kp.getPrivate();
        RSAPublicKey rpk = (RSAPublicKey)publicKey;
        RSAPrivateKey rpr= (RSAPrivateKey)privateKey;
        //三个特征值都是BigInteger类型。
        BigInteger N = rpk.getModulus();//N值
        BigInteger e = rpk.getPublicExponent();//e值
        BigInteger d  = rpr.getPrivateExponent();//d值
        Map<String, String> map = new HashMap<String, String>();
        //将BigInteger转为byte[],然后以base64保存
        map.put("N",new String(Base64.getDecoder().decode(N.toByteArray())));
        map.put("e", new String(Base64.getDecoder().decode(e.toByteArray())));
        map.put("d", new String(Base64.getDecoder().decode(d.toByteArray())));
        return map;
    }


    /**
     * 以base64编码密钥
     *
     * 通过密钥生成器生成公钥，私钥后，调用publicKey.getEncoded()和privateKey.getEncoded()，此时它生成的比特编码是有独特格式的（公钥是X.509，私钥是PKCS#8）可以使用publicKey.getFormat()，privateKey.getFormat();进行查看。之后对字节码进行Base64编码就行了。
     */
    public Map<String ,String> generateKeyPairMap() throws Exception{
    
    
        /** RSA算法要求有一个可信任的随机数源 */
        SecureRandom sr = new SecureRandom();
        /** 为RSA算法创建一个KeyPairGenerator对象 */
        KeyPairGenerator kpg = KeyPairGenerator.getInstance(ALGORITHM);
        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
        kpg.initialize(KEYSIZE, sr);
        /** 生成密匙对 */
        KeyPair kp = kpg.generateKeyPair();
        /** 得到公钥 */
        Key publicKey = kp.getPublic();
        /** 得到私钥 */
        Key privateKey = kp.getPrivate();

        //公钥字节
        byte[] pb = publicKey.getEncoded();
        //由于加密后的密文都是字节码形式的，我们要以字符串方式保存或传输的话，可以使用Base64编码。
        String pbStr = Base64.getEncoder().encodeToString(pb);
        //私钥字节
        byte[] pr = privateKey.getEncoded();
        String prStr = Base64.getEncoder().encodeToString(pr);

        Map<String, String> map = new HashMap<>();
        map.put(PUBLIC_KEY_FILE,pbStr);
        map.put(PRIVATE_KEY_FILE, prStr);
        return map;
    }

    /**序列化生成密钥对*/
    private static void generateKeyPair() throws Exception {
    
    
        /** RSA算法要求有一个可信任的随机数源 */
        SecureRandom sr = new SecureRandom();
        /** 为RSA算法创建一个KeyPairGenerator对象 */
        KeyPairGenerator kpg = KeyPairGenerator.getInstance(ALGORITHM);
        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
        kpg.initialize(KEYSIZE, sr);
        /** 生成密匙对 */
        KeyPair kp = kpg.generateKeyPair();
        /** 得到公钥 */
        Key publicKey = kp.getPublic();
        /** 得到私钥 */
        Key privateKey = kp.getPrivate();
        /** 用对象流将生成的密钥写入文件 */
        ObjectOutputStream publicOOS = new ObjectOutputStream(new FileOutputStream(
                PUBLIC_KEY_FILE));
        ObjectOutputStream privateOOS = new ObjectOutputStream(new FileOutputStream(
                PRIVATE_KEY_FILE));
        publicOOS.writeObject(publicKey);
        privateOOS.writeObject(privateKey);
        /** 清空缓存，关闭文件输出流 */
        publicOOS.close();
        privateOOS.close();
    }

    /**加密方法 source： 源数据*/
    public static byte[] encrypt(String source) throws Exception {
    
    

        /** 将文件中的公钥对象读出 */
        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(
                PUBLIC_KEY_FILE));
        Key key = (Key) ois.readObject();
        ois.close();
        /** 得到Cipher对象来实现对源数据的RSA加密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM_MODEL);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] b = source.getBytes();
        /** 执行加密操作 */
        return cipher.doFinal(b);
    }

    /**解密算法 cryptograph:密文*/
    public static String decrypt(byte[] cryptograph) throws Exception {
    
    
        /** 将文件中的私钥对象读出 */
        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(
                PRIVATE_KEY_FILE));
        Key key = (Key) ois.readObject();
        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM_MODEL);
        cipher.init(Cipher.DECRYPT_MODE, key);
        /** 执行解密操作 */
        byte[] bytes = cipher.doFinal(cryptograph);
        return new String(bytes);
    }

    public static void main(String[] args) throws Exception {
    
    
        //生成密钥对
        generateKeyPair();

        // 要加密的字符串
        String source = "Hello World!";

        // 生成的密文
        byte[] cryptograph = encrypt(source);

        //可以将密文进行base64编码进行传输
        System.out.println(Base64.getEncoder().encodeToString(cryptograph));

        // 解密密文
        String target = decrypt(cryptograph);
        System.out.println(target);
    }
}

resultado de ejecución del método principal

dQzpKmKcQJkQqBLvCeO/9SWid+9GwaTljOXDRWojhmgUQXxTcvYsbi4QlEk643SiJkMpbqjnT/oCq08aur9FIu5eF2QhxlrH/A+OiA4GyG3kEe/ZTXbUwDeNnxiQc5UeWLX2U3yZZp0YHZe3MNKkjRoFq6L2co1+Pmp3C/qIsLE=
Hello World!