Java解密时出错

Question

我有两个名为 Encryption.java 和 Decryption.java 的类。我想使用 encrypt.java 类加密文本文件并从解密.java 类解密。我可以成功加密文本文件，但无法以相同的方式解密它。谁能告诉我为什么不呢？

这是加密.java:

 public class Encrypt{


public static void main(String[] args) throws Exception {

   String FileName = "D:/ashok/normal.txt";
    String FileName1 = "D:/ashok/encrypted.txt";


    KeyGenerator KeyGen = KeyGenerator.getInstance("AES");
    KeyGen.init(128);

    SecretKey SecKey = KeyGen.generateKey();

    Cipher AesCipher = Cipher.getInstance("AES");



    byte[] cipherText = Files.readAllBytes(Paths.get(FileName));
    AesCipher.init(Cipher.ENCRYPT_MODE, SecKey);
    byte[] byteCipherText = AesCipher.doFinal(cipherText);
    Files.write(Paths.get(FileName1), byteCipherText);
 }

这是我的decrypt.java类:

 class decrypt{
 public static void main(String[] args) {
    try {
   String FileName1 = "D:/ashok/encrypted.txt";
        String FileName2 = "D:/ashok/decrypted.txt";

        KeyGenerator KeyGen = KeyGenerator.getInstance("AES");
        KeyGen.init(128);

        SecretKey SecKey = KeyGen.generateKey();

        Cipher AesCipher =  Cipher.getInstance("AES");
        byte[] cipherrText = Files.readAllBytes(Paths.get(FileName1));

        AesCipher.init(Cipher.DECRYPT_MODE, SecKey);
        byte[] bytePlainText = AesCipher.doFinal(cipherrText);
        Files.write(Paths.get(FileName2), bytePlainText);  }}

并且在解密类运行时出现错误，如下所示

 javax.crypto.BadPaddingException: Given final block not properly padded
  at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:811)
  at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:676)
  at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:313)
  at javax.crypto.Cipher.doFinal(Cipher.java:2086)
  at decryption.main(decryption.java:79)

Answer 1

您使用 SecretKey SecKey = KeyGen.generateKey() 生成用于加密的 key ，这很好，但是当您解密时，您会尝试使用新 key ，而不是您以前使用的 key 加密文本。您需要保存 key ，以便可以使用它进行解密。