aes加密解密通过tcp.Input 长度必须是16的倍数，用padded cipher解密

Question

我在运行程序

时看到这个 "Input length must be multiple of 16 when decrypting with padded cipher" 错误

RealEchoServer.java

import java.io.*;
import java.net.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class RealEchoServer {

public static void main(String[] args) {
    int i = 1;
    try {
        ServerSocket s = new ServerSocket(9003);

        for (;;) {
            Socket incoming = s.accept();
            System.out.println("Spawning " + i);
            new RealEchoHandler(incoming, i).start();
            i++;
        }
    } catch (Exception e) {
        System.out.println(e);
    }
 }
}

class RealEchoHandler extends Thread {

DataInputStream in;
DataOutputStream out;
private Socket incoming;
private int counter;

public RealEchoHandler(Socket i, int c) {
    incoming = i;
    counter = c;
}

public void run() {
    try {

        String key1 = "1234567812345678";
        byte[] key2 = key1.getBytes();
        SecretKeySpec secret = new SecretKeySpec(key2, "AES");
        String msg = "Singapore Malaysia Japan India Indonesia HongKong Taiwan China England";
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, secret);
        byte[] encrypted = cipher.doFinal(msg.getBytes());

        in = new DataInputStream(incoming.getInputStream());
        out = new DataOutputStream(incoming.getOutputStream());

        boolean done = false;
        String str = "";
        out.writeUTF("Connected!\n");
        out.flush();
        while (!done) {
            out.writeUTF(">");
            out.flush();
            str = in.readUTF();
            System.out.println(in + ":" + str);
            if (str == null) {
                done = true;
            } else {
                System.out.println("Sending Ciphertext : " + new String(encrypted));
                out.writeUTF(new String(encrypted));
                out.flush();
            }
        }
        incoming.close();
    } catch (Exception e) {
        System.out.println(e);
    }
 }
}

RealSocketTest.java

   import java.io.*;
   import java.net.*;
   import java.security.*;
   import javax.crypto.*;
   import javax.crypto.spec.*;
   import java.util.*;

 class RealSocketTest {
 public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {

    String str = "";
    String str2 = "";
    DataOutputStream out;
    DataInputStream in;

    try {
        Socket t = new Socket("127.0.0.1", 9003);
        in = new DataInputStream(t.getInputStream());
        out = new DataOutputStream(t.getOutputStream());
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        boolean more = true;
        System.out.println(in.readUTF());

        while (more) {
            str = in.readUTF();
            System.out.print(str);
            str2 = br.readLine();
            out.writeUTF(str2);
            out.flush();
            str = in.readUTF();

            System.out.println("Encrypted Info: " + str);

            try {

                String key1 = "1234567812345678";
                byte[] key2 = key1.getBytes();
                SecretKeySpec secret = new SecretKeySpec(key2, "AES");
                Cipher cipher = Cipher.getInstance("AES");
                cipher.init(Cipher.DECRYPT_MODE, secret);
                byte[] decrypted = cipher.doFinal(str.getBytes());
                System.out.println("Decrypted Info: " + new String(decrypted));
            } catch (BadPaddingException e) {
                System.out.println("Wrong Key!");
            } catch (InvalidKeyException f) {
                System.out.println("Invalid Key!");
            }
        }
    } catch (IOException e) {
        System.out.println("Error");
    }
  }
}

我在这里读到一个类似的问题Illegal Block Size Exception Input length must be multiple of 16 when decrypting with padded cipher，但我不明白如何改变我的，因为它看起来与我的很不一样。

那么 added/changed 应该怎样解密？

Answer 1

问题是密文可能包含所有可能的字节值。另一方面，许多字节值不可打印，因此不是有效的 UTF-8 编码。当你用它制作一个字符串时 new String(encrypted)，它会悄悄地丢弃一些字节，你将无法成功解密密文。

两个可能的修复：

将密文编码为 Base64 或 Hex，以用于基于文本的协议。
使用DataOutputStream::write()方法使其成为不编码的二进制协议。

其他安全内容：

始终为预期的密码实例指定完整的字符串。不同的提供者可能有不同的默认值，并且客户端和服务器可能不使用相同的方法。示例：AES/ECB/PKCS5Padding.
切勿使用 ECB 模式。它在语义上不安全。至少使用带有随机 IV 的 CBC（在密文前面加上 IV 或按顺序将其写入流）。
检查您的密文是否被操纵。通过使用像 GCM（AES/GCM/NoPadding 和 GCMParameters）这样的身份验证模式，这很容易做到。如果你不想要那样，那么至少尝试实现一个加密然后 MAC 方案，你 HMAC 密文（使用不同的密钥）并在解密之前检查它。

aes加密解密通过tcp.Input 长度必须是16的倍数，用padded cipher解密

aes encryption and decryption through tcp.Input length must be multiple of 16 when decrypting with padded cipher

java

encryption

cryptography

tcp

aes