无法修复“错误：使用密码密码解密时，输入长度必须是16的倍数”

Question

Ello！我正在开发一个聊天应用程序，通过AES/CBC/PKCS5 Padding加密它的数据。它通过客户端将加密消息发送到服务器进行发送和解密。不幸的是，每当我解密消息时，我得到的错误如下：javax.crypto.IllegalBlockSizeException：使用填充密码解密时，输入长度必须是16的倍数。加密是基于这个程序:(http://www.scottjjohnson.com/blog/AesWithCbcExample.java），它工作得很好，我看不出我的代码和那个之间的区别，除了我必须从字符串转换为字节数组。这里是我的代码代码：

客户端（加密）：

String message = textField.getText(); 
// generate a key 
KeyGenerator keygen = KeyGenerator.getInstance("AES"); 
keygen.init(128); // To use 256 bit keys, you need the "unlimited strength" encryption policy files from Sun. 
byte[] key = keygen.generateKey().getEncoded(); 
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES"); 

// build the initialization vector. This example is all zeros, but it 
// could be any value or generated using a random number generator. 
byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; 
IvParameterSpec ivspec = new IvParameterSpec(iv); 

// initialize the cipher for encrypt mode 
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); 
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivspec); 

// encrypt the message 
byte[] encrypted = cipher.doFinal(message.getBytes()); 
System.out.println("Ciphertext: " + encrypted + "\n"); 
System.out.println(encrypted); 
out.println(encrypted); 
textField.setText(""); 

服务器端：

String input = in.readLine(); 
writer.println("MESSAGE " + input); 

客户端（解密）：

//DECRYPTION 
System.out.println(line); 
line = line.substring(8); 
System.out.println(line); 

// generate a key 
KeyGenerator keygen = KeyGenerator.getInstance("AES"); 
keygen.init(128); // To use 256 bit keys, you need the "unlimited strength" encryption policy files from Sun. 
byte[] key = keygen.generateKey().getEncoded(); 
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES"); 

// build the initialization vector. This example is all zeros, but it 
// could be any value or generated using a random number generator. 
byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; 
IvParameterSpec ivspec = new IvParameterSpec(iv); 

// reinitialize the cipher for decryption 
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); 
cipher.init(Cipher.DECRYPT_MODE, skeySpec, ivspec); 

// decrypt the message 
byte[] decrypted = cipher.doFinal(line.getBytes()); 
System.out.println("Plaintext: " + new String(decrypted) + "\n"); 
messageArea.append(name + ": " + decrypted + "\n"); 
messageArea.setCaretPosition(messageArea.getDocument().getLength()); 

Answer 1

您的问题无关与密码学。您无法在您的客户端和服务器之间正确传输数据。

我相当肯定out.println(encrypted)是不你想要做的，虽然我不完全清楚，因为我不知道out类型是什么。您也不应该在解密代码中调用line.getBytes()。

您应该将您的密文转换为非有损字符串形式，如十六进制或base64。因此，尝试：

out.println(DatatypeConverter.printHexBinary(encrypted)); 

和

byte[] decrypted = cipher.doFinal(DatatypeConverter.parseHexBinary(line));