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我正在编写基于客户端-服务器的 Java 应用程序，但我遇到了一个问题，因为它在客户端和服务器中构造 ObjectInputStream 时都会挂起。

客户：

Socket socket = new Socket("localhost", 9999);

outCiph = new CipherOutputStream(socket.getOutputStream(), AES.getEncryptCipher("key"));
out = new ObjectOutputStream(outCiph);
inCiph = new CipherInputStream(socket.getInputStream(), AES.getDecryptCipher("key"));
in = new ObjectInputStream(inCiph);

try
{
String text = "test!";

out.writeObject(text);
out.flush();

if (out != null)
out.close();

if (in != null)
in.close();
}
catch (IOException ex)
{
System.err.println(ex.toString());
}

服务器：

ServerSocket serverSocket = new ServerSocket(9999);
Socket socket = serverSocket.accept();

outCiph = new CipherOutputStream(socket.getOutputStream(), AES.getEncryptCipher("key"));
out = new ObjectOutputStream(outCiph);
inCiph = new CipherInputStream(socket.getInputStream(), AES.getDecryptCipher("key"));
in = new ObjectInputStream(inCiph);

try
{
String rec = (String) in.readObject();
System.out.println("Received from client: " + rec);

if (out != null)
out.close();

if (in != null)
in.close();

}
catch (IOException ex)
{
System.err.println(ex.toString() + " in start()");
}
catch (ClassNotFoundException ex)
{
System.err.println(ex.toString());
}

AES：

// I'm not author of generateKey method so I've no idea if is it correct
private static byte[] generateKey(String pass) throws UnsupportedEncodingException, NoSuchAlgorithmException
{
MessageDigest sha = MessageDigest.getInstance("SHA-256");
byte[] passBytes = pass.getBytes("ASCII");
byte[] sha256Bytes = sha.digest(passBytes);


byte[] key = new byte[16];
int j = 0;
for (int i = 0; i < sha256Bytes.length; i++)
{
    if (i % 2 == 0)
    {
    key[j] = sha256Bytes[i];
    j++;
    }
}
return key;
}

public static Cipher getEncryptCipher(String pass)
{
try
{
    SecretKeySpec skeySpec = new SecretKeySpec(generateKey(pass), "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    return cipher;
}
catch (Exception ex) // just for clarity
{
    Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}

public static Cipher getDecryptCipher(String pass)
{
try
{
    SecretKeySpec skeySpec = new SecretKeySpec(generateKey(pass), "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    return cipher;
}
catch (Exception ex) // just for clarity
{
    Logger.getLogger(AES.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}

当我不使用 CipherInput/OutputStream 时，一切正常，所以问题与 CipherInput/OutputStream 有关。

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1 回答 1

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只有在发送完所有信息后才需要创建 ObjectInputStream ，因为 ObjectInputStream 的构造函数会阻塞，因为它需要读取标头。

Normally, all the bytes would have been written by the ObjectOutputStream, but now the CipherOutputStream is waiting until it has a full 16 byte block (in the case of AES) before it sends the (last part of the) header over. Maybe AES in stream cipher mode (CTR or GCM) would be more useful here as it uses per byte encryption, and would be able to directly send each byte.

于 2012-02-23T00:38:09.070 回答