content: package com.platform.utils;
  
  import org.apache.commons.codec.binary.Base64;
  import javax.crypto.Cipher;
  import java.io.ByteArrayOutputStream;
  import java.security.*;
  import java.security.interfaces.RSAPrivateKey;
  import java.security.interfaces.RSAPublicKey;
  import java.security.spec.PKCS8EncodedKeySpec;
  import java.security.spec.X509EncodedKeySpec;
  
  /**
   * @author AllDataDC
   * https://www.cnblogs.com/nihaorz/p/10690643.html
   * @description Rsa 工具类，公钥私钥生成，加解密
   * @date 2023-01-27
   **/
  public class RsaUtils {
  
      private static final String SRC = "123456";
  
      public static void main(String[] args) throws Exception {
          System.out.println("\n");
          RsaKeyPair keyPair = generateKeyPair();
          System.out.println("公钥：" + keyPair.getPublicKey());
          System.out.println("私钥：" + keyPair.getPrivateKey());
          System.out.println("\n");
          test1(keyPair);
          System.out.println("\n");
          test2(keyPair);
          System.out.println("\n");
      }
  
      /**
       * 公钥加密私钥解密
       */
      private static void test1(RsaKeyPair keyPair) throws Exception {
          System.out.println("***************** 公钥加密私钥解密开始 *****************");
          String text1 = encryptByPublicKey(keyPair.getPublicKey(), RsaUtils.SRC);
          String text2 = decryptByPrivateKey(keyPair.getPrivateKey(), text1);
          System.out.println("加密前：" + RsaUtils.SRC);
          System.out.println("加密后：" + text1);
          System.out.println("解密后：" + text2);
          if (RsaUtils.SRC.equals(text2)) {
              System.out.println("解密字符串和原始字符串一致，解密成功");
          } else {
              System.out.println("解密字符串和原始字符串不一致，解密失败");
          }
          System.out.println("***************** 公钥加密私钥解密结束 *****************");
      }
  
      /**
       * 私钥加密公钥解密
       * @throws Exception /
       */
      private static void test2(RsaKeyPair keyPair) throws Exception {
          System.out.println("***************** 私钥加密公钥解密开始 *****************");
          String text1 = encryptByPrivateKey(keyPair.getPrivateKey(), RsaUtils.SRC);
          String text2 = decryptByPublicKey(keyPair.getPublicKey(), text1);
          System.out.println("加密前：" + RsaUtils.SRC);
          System.out.println("加密后：" + text1);
          System.out.println("解密后：" + text2);
          if (RsaUtils.SRC.equals(text2)) {
              System.out.println("解密字符串和原始字符串一致，解密成功");
          } else {
              System.out.println("解密字符串和原始字符串不一致，解密失败");
          }
          System.out.println("***************** 私钥加密公钥解密结束 *****************");
      }
  
      /**
       * 公钥解密
       *
       * @param publicKeyText 公钥
       * @param text 待解密的信息
       * @return /
       * @throws Exception /
       */
      public static String decryptByPublicKey(String publicKeyText, String text) throws Exception {
          X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
          KeyFactory keyFactory = KeyFactory.getInstance("RSA");
          PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
          Cipher cipher = Cipher.getInstance("RSA");
          cipher.init(Cipher.DECRYPT_MODE, publicKey);
          byte[] result = doLongerCipherFinal(Cipher.DECRYPT_MODE, cipher, Base64.decodeBase64(text));
          return new String(result);
      }
  
      /**
       * 私钥加密
       *
       * @param privateKeyText 私钥
       * @param text 待加密的信息
       * @return /
       * @throws Exception /
       */
      public static String encryptByPrivateKey(String privateKeyText, String text) throws Exception {
          PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
          KeyFactory keyFactory = KeyFactory.getInstance("RSA");
          PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
          Cipher cipher = Cipher.getInstance("RSA");
          cipher.init(Cipher.ENCRYPT_MODE, privateKey);
          byte[] result = doLongerCipherFinal(Cipher.ENCRYPT_MODE, cipher, text.getBytes());
          return Base64.encodeBase64String(result);
      }
  
      /**
       * 私钥解密
       *
       * @param privateKeyText 私钥
       * @param text 待解密的文本
       * @return /
       * @throws Exception /
       */
      public static String decryptByPrivateKey(String privateKeyText, String text) throws Exception {
          PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
          KeyFactory keyFactory = KeyFactory.getInstance("RSA");
          PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
          Cipher cipher = Cipher.getInstance("RSA");
          cipher.init(Cipher.DECRYPT_MODE, privateKey);
          byte[] result = doLongerCipherFinal(Cipher.DECRYPT_MODE, cipher, Base64.decodeBase64(text));
          return new String(result);
      }
  
      /**
       * 公钥加密
       *
       * @param publicKeyText 公钥
       * @param text 待加密的文本
       * @return /
       */
      public static String encryptByPublicKey(String publicKeyText, String text) throws Exception {
          X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
          KeyFactory keyFactory = KeyFactory.getInstance("RSA");
          PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
          Cipher cipher = Cipher.getInstance("RSA");
          cipher.init(Cipher.ENCRYPT_MODE, publicKey);
          byte[] result = doLongerCipherFinal(Cipher.ENCRYPT_MODE, cipher, text.getBytes());
          return Base64.encodeBase64String(result);
      }
  
      private static byte[] doLongerCipherFinal(int opMode,Cipher cipher, byte[] source) throws Exception {
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          if (opMode == Cipher.DECRYPT_MODE) {
              out.write(cipher.doFinal(source));
          } else {
              int offset = 0;
              int totalSize = source.length;
              while (totalSize - offset > 0) {
                  int size = Math.min(cipher.getOutputSize(0) - 11, totalSize - offset);
                  out.write(cipher.doFinal(source, offset, size));
                  offset += size;
              }
          }
          out.close();
          return out.toByteArray();
      }
  
      /**
       * 构建RSA密钥对
       *
       * @return /
       * @throws NoSuchAlgorithmException /
       */
      public static RsaKeyPair generateKeyPair() throws NoSuchAlgorithmException {
          KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
          keyPairGenerator.initialize(1024);
          KeyPair keyPair = keyPairGenerator.generateKeyPair();
          RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
          RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
          String publicKeyString = Base64.encodeBase64String(rsaPublicKey.getEncoded());
          String privateKeyString = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
          return new RsaKeyPair(publicKeyString, privateKeyString);
      }
  
  
      /**
       * RSA密钥对对象
       */
      public static class RsaKeyPair {
  
          private final String publicKey;
          private final String privateKey;
  
          public RsaKeyPair(String publicKey, String privateKey) {
              this.publicKey = publicKey;
              this.privateKey = privateKey;
          }
  
          public String getPublicKey() {
              return publicKey;
          }
  
          public String getPrivateKey() {
              return privateKey;
          }
  
      }
  }
  