如何解密使用此代码加密的文本？

问题描述

我在网站上找到此代码。我不明白该如何解码。你能帮我吗？

import java.util.Base64;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class AES {
    
    public static String encrypt(String strToEncrypt) throws Exception {
        byte[] plaintext = strToEncrypt.getBytes("UTF-8");
        KeyGenerator keygen = KeyGenerator.getInstance("AES");
        keygen.init(256);
        SecretKey key = keygen.generateKey();
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.ENCRYPT_MODE,key);
        byte[] ciphertext = cipher.doFinal(plaintext);
        return Base64.getEncoder().encodetoString(ciphertext);
    }

}

解决方法

欢迎使用Stackoverflow。在下面，您可以找到AES CBC字符串加密的完整工作示例。请注意，您需要将随机创建的密钥和初始化向量安全地存储到（后来的）加密数据中，因为否则，（完全）无法恢复数据。加密和解密需要使用相同的密钥和iv。

因为键＆iv是字节数组，所以我将它们编码为Base64以更好地存储。

安全警告：这是一个简单的示例，用于演示AES CBC加密/解密而不进行任何适当的异常处理。该代码仅用于教育目的，不应在生产中使用！

结果：

AES CBC String Encryption with random key + iv
This is a simple example to demonstrate AES CBC en-/decryption without any proper exception handling.
The code is for educational purposes only and should not be used in production.

save the key and iv securely,without the data it will be NOT possible to decrypt !!
key in Base64-format: Nf41yG0F+MdFQnp3p3mIrWOk+2kxQ/LmyVcHKEKi5sQ=
iv in Base64-format:  yICmqsMaIdwsYsUDUsLWnA==
plaintext:     The quick brown fox jumps over the lazy dog
ciphertext:    PJNEV3H3Zh3TQx7B9jpg29gV59LgJ6baOpNM82dMOpPClJouYnq+hKVUQTDEkkdI
decryptedtext: The quick brown fox jumps over the lazy dog

代码：

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Base64;

public class AesCbcTextEncryptionRandomKeyIv {
    public static void main(String[] args) throws NoSuchPaddingException,InvalidKeyException,NoSuchAlgorithmException,IllegalBlockSizeException,BadPaddingException,InvalidAlgorithmParameterException {
        System.out.println("AES CBC String Encryption with random key + iv");
        System.out.println("This is a simple example to demonstrate AES CBC en-/decryption without any proper exception handling.");
        System.out.println("The code is for educational purposes only and should not be used in production.\n");

        String plaintext = "The quick brown fox jumps over the lazy dog";

        // generate a random key & initialization vector
        byte[] key = new byte[32]; // key for aes 256 encryption,32 byte length
        byte[] iv = new byte[16]; // initialization vector with 16 byte length
        SecureRandom secureRandom = new SecureRandom();
        secureRandom.nextBytes(key);
        secureRandom.nextBytes(iv);
        System.out.println("save the key and iv securely,without the data it will be NOT possible to decrypt !!");
        // convert key & iv in base64 format for storage reasons
        String keyBase64 = Base64.getEncoder().encodeToString(key);
        String ivBase64 = Base64.getEncoder().encodeToString(iv);
        System.out.println("key in Base64-format: " + keyBase64);
        System.out.println("iv in Base64-format:  " + ivBase64);

        // encryption
        String ciphertext = encrypt(keyBase64,ivBase64,plaintext);
        System.out.println("plaintext:     " + plaintext);
        System.out.println("ciphertext:    " + ciphertext);

        // decryption
        String decryptedtext = decrypt(keyBase64,ciphertext);
        System.out.println("decryptedtext: " + decryptedtext);

    }
    public static String encrypt(String keyBase64,String ivBase64,String plaintext)
            throws NoSuchPaddingException,InvalidAlgorithmParameterException,IllegalBlockSizeException {
        SecretKeySpec secretKeySpec = new SecretKeySpec(Base64.getDecoder().decode(keyBase64),"AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(Base64.getDecoder().decode(ivBase64));
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.ENCRYPT_MODE,secretKeySpec,ivParameterSpec);
        return Base64.getEncoder().encodeToString(cipher.doFinal(plaintext.getBytes(StandardCharsets.UTF_8)));
    }

    public static String decrypt(String keyBase64,String ciphertext)
            throws NoSuchPaddingException,"AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(Base64.getDecoder().decode(ivBase64));
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.DECRYPT_MODE,ivParameterSpec);
        return new String(cipher.doFinal(Base64.getDecoder().decode(ciphertext)),StandardCharsets.UTF_8);
    }
}

encryption java java