关于java:RSA加密-Java

前言

• 简介
  RSA公开密钥明码体制是一种应用不同的加密密钥与解密密钥，“由已知加密密钥推导出解密密钥在计算上是不可行的”明码体制。
• 原理
  依据数论，寻求两个大素数比较简单，而将它们的乘积进行因式分解却极其艰难，因而能够将乘积公开作为加密密钥，即公钥，而两个大素数组合成私钥。公钥是可公布的供任何人应用，私钥则为本人所有，供解密之用。
• 运算速度
  因为进行的都是大数计算，使得RSA最快的状况也比DES慢上好几倍，无论是软件还是硬件实现。速度始终是RSA的缺点。一般来说只用于大量数据加密。RSA的速度比对应同样安全级别的对称明码算法要慢1000倍左右。
• 其它链接
  RSA加密 - Vue
  RSA分段加密 - Java
  RSA分段解密 - Vue

具体实现

• 实现类

  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;/** * @Description RSA加密算法 * @author coisini * @date Jul 5, 2021 * @Version 1.0 */public class RSAUtil {  private static final String ALGO = "RSA";  private static final String CHARSET = "UTF-8";  /**   * 公钥 由generateKeyPair()生成   */  private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCaaI4MBywkCjIppZnraqN3pbrcZTq/t0+aMBo8K3pK9BDD6XkM6N2Yfcva7BSFbUWuAcI7piXak0UKn9CElDuhNzUSgQn4IXKxIt3Iva5cV83qYumj+0yRjjLT8Muu1Y1rgBZjY9oBwhVoV+Twg25+UJ+6Q6HM4xTwQQJDoyy4jwIDAQAB";  /**   * 私钥 由generateKeyPair()生成   */  private static final String PRIVATE_KEY = "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";  /**   * 生成密钥对   * @throws NoSuchAlgorithmException   */  private static void generateKeyPair() 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(ALGO);      // 初始化密钥对生成器，密钥大小为 96-1024 位      keyPairGen.initialize(1024, new SecureRandom());      // 生成一个密钥对，保留在 keyPair 中      KeyPair keyPair = keyPairGen.generateKeyPair();      // 失去私钥      RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();      // 失去公钥      RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();      String publicKeyString = new String(Base64.getEncoder().encode(publicKey.getEncoded()));      // 失去私钥字符串      String privateKeyString = new String(Base64.getEncoder().encode((privateKey.getEncoded())));      System.out.println(publicKeyString);      System.out.println(privateKeyString);  }  /**   * RSA公钥加密   * @param data 加密字符串   * @return 密文   * @throws Exception 加密过程中的异样信息   */  private static String encryptByPublicKey(String data) throws Exception {      // base64 编码的公钥      byte[] decoded = Base64.getDecoder().decode(PUBLIC_KEY);      RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance(ALGO).generatePublic(new X509EncodedKeySpec(decoded));      // RSA加密      Cipher cipher = Cipher.getInstance(ALGO);      // 公钥加密      cipher.init(Cipher.ENCRYPT_MODE, pubKey);      return Base64.getEncoder().encodeToString(cipher.doFinal(data.getBytes(CHARSET)));  }  /**   * RSA私钥解密   * @param data 加密字符串   * @return 明文   * @throws Exception 解密过程中的异样信息   */  private static String decryptByPrivateKey(String data) throws Exception {      byte[] inputByte = Base64.getDecoder().decode(data.getBytes(CHARSET));      // base64 编码的私钥      byte[] decoded = Base64.getDecoder().decode(PRIVATE_KEY);      RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance(ALGO).generatePrivate(new PKCS8EncodedKeySpec(decoded));      // RSA 解密      Cipher cipher = Cipher.getInstance(ALGO);      // 私钥解密      cipher.init(Cipher.DECRYPT_MODE, priKey);      return new String(cipher.doFinal(inputByte));  }  /**   * 私钥加密   * 前端公钥解密   * @param data 加密字符串   * @return 密文   * @throws Exception 加密过程中的异样信息   */  public static String encryptByPrivateKey(String data) throws Exception {      // 获取私钥      PrivateKey privateKey = getPrivateKey(PRIVATE_KEY);      Cipher cipher = Cipher.getInstance("RSA");      cipher.init(Cipher.ENCRYPT_MODE, privateKey);      byte[] cipherText = cipher.doFinal(data.getBytes());      String cipherStr = Base64.getEncoder().encodeToString(cipherText);      return cipherStr;  }  /**   * 公钥解密   * @param data 解密字符串   * @return 明文   * @throws Exception 解密过程中的异样信息   */  public static String decryptByPublicKey(String data) throws Exception {      // 获取公钥      PublicKey publicKey = getPublicKey(PUBLIC_KEY);      Cipher cipher = Cipher.getInstance("RSA");      cipher.init(Cipher.DECRYPT_MODE, publicKey);      byte[] cipherText = Base64.getDecoder().decode(data);      byte[] decryptText = cipher.doFinal(cipherText);      return new String(decryptText);  }  /**   * 将base64编码后的私钥字符串转成PrivateKey实例   * @param privateKey 私钥   * @return PrivateKey实例   * @throws Exception 异样信息   */  private static PrivateKey getPrivateKey(String privateKey) throws Exception {      byte[] keyBytes = Base64.getDecoder().decode(privateKey);      PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);      KeyFactory keyFactory = KeyFactory.getInstance(ALGO);      return keyFactory.generatePrivate(keySpec);  }  /**   * 将base64编码后的公钥字符串转成PublicKey实例   * @param publicKey 公钥   * @return PublicKey实例   * @throws Exception 异样信息   */  private static PublicKey getPublicKey(String publicKey) throws Exception {      byte[] keyBytes = Base64.getDecoder().decode(publicKey);      X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);      KeyFactory keyFactory = KeyFactory.getInstance(ALGO);      return keyFactory.generatePublic(keySpec);  }  public static void main(String[] args) {      String data = "RSA encrypt!";      try {          // generateKeyPair();          String encryDataByPublicKey = encryptByPublicKey(data);          System.out.println("encryDataByPublicKey: " + encryDataByPublicKey);          String decryDataByPrivateKey = decryptByPrivateKey(encryDataByPublicKey);          System.out.println("decryDataByPrivateKey: " + decryDataByPrivateKey);          String encryDataByPrivateKey = encryptByPrivateKey(data);          System.out.println("encryDataByPrivateKey: " + encryDataByPrivateKey);          String decryDataByPublicKey = decryptByPublicKey(encryDataByPrivateKey);          System.out.println("decryDataByPublicKey: " + decryDataByPublicKey);      } catch (Exception e) {          e.printStackTrace();      }  }}

• 后果如下所示：
  
  
  

源码

• GitHub： https://github.com/Maggieq8324/coisini-rsa
• Gitee：https://gitee.com/maggieq8324/coisini-rsa