Java实现RSA算法的方法详解

package com.imooc.security.rsa;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
public class ImoocRSA {
  private static String src = "cakin24 security rsa";
  public static void main(String[] args) {
    jdkRSA();
  }
  public static void jdkRSA() {
    try {
      //1.初始化密钥
      KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
      keyPairGenerator.initialize(512);
      KeyPair keyPair = keyPairGenerator.generateKeyPair();
      RSAPublicKey rsaPublicKey = (RSAPublicKey)keyPair.getPublic();
      RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)keyPair.getPrivate();
      System.out.println("Public Key : " + Base64.encodeBase64String(rsaPublicKey.getEncoded()));
      System.out.println("Private Key : " + Base64.encodeBase64String(rsaPrivateKey.getEncoded()));
      //2.私钥加密、公钥解密――加密
      PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
      KeyFactory keyFactory = KeyFactory.getInstance("RSA");
      PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
      Cipher cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.ENCRYPT_MODE, privateKey);
      byte[] result = cipher.doFinal(src.getBytes());
      System.out.println("私钥加密、公钥解密――加密 : " + Base64.encodeBase64String(result));
      //3.私钥加密、公钥解密――解密
      X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
      keyFactory = KeyFactory.getInstance("RSA");
      PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
      cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.DECRYPT_MODE, publicKey);
      result = cipher.doFinal(result);
      System.out.println("私钥加密、公钥解密――解密：" + new String(result));
      //4.公钥加密、私钥解密――加密
      x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
      keyFactory = KeyFactory.getInstance("RSA");
      publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
      cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.ENCRYPT_MODE, publicKey);
      result = cipher.doFinal(src.getBytes());
      System.out.println("公钥加密、私钥解密――加密 : " + Base64.encodeBase64String(result));
      //5.公钥加密、私钥解密――解密
      pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
      keyFactory = KeyFactory.getInstance("RSA");
      privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
      cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.DECRYPT_MODE, privateKey);
      result = cipher.doFinal(result);
      System.out.println("公钥加密、私钥解密――解密：" + new String(result));
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}