我正在尝试实现一个基本的Diffie-Hellman协议,并且代码成功到需要使用DES解密发送的值时。我看了很多例子,其中关键是不匹配,但我在连接的两端打印它们的值,它们都完全相同。我还尝试了多种填充方案以及更改密钥的生成方式。
我的最后一次尝试是将参数IvParameterSpec添加到密码init,但这只解决了其中一个错误。
我在一台机器上运行它,其中套接字通过localhost连接,我一直在检查任何一方的问题,发送的数据与接收的数据不完全匹配,但发送中没有任何改变。但是,我注意到,当打印套接字两侧的每个字节数组时,客户端比服务器长得多,看起来像是填充(?)
我得到的错误是说最后一个块填充不正确,因此解密失败
我的服务器代码(未按预期工作的一方):
public static void main(String[] args) {
ServerSocket welcomeSocket = null;
// Creates a connectable socket on port 6789
try {
welcomeSocket = new ServerSocket(6789);
} catch (IOException e) {
e.printStackTrace();
}
while(true){
try{
double k2, B, A;
double n = 13;
double g = 61;
long y = 7;
B = (Math.pow(g, y))%n;
System.out.println("Accepting connections");
// Accept an incoming connection on the socket server
Socket connectionSocket = welcomeSocket.accept();
// Creates a read and write stream for that client
DataInputStream inFromClient = new DataInputStream(connectionSocket.getInputStream());
DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
// Sends the double to the client
outToClient.writeDouble(B);
System.out.println("Sent " + B);
// Reads the number sent by the Client
A = inFromClient.readDouble();
System.out.println("Received " + A);
// Modifies the number
k2 = (Math.pow(A, y))%n;
System.out.println("DES key seed = " + k2);
byte[] deskeydata = toByteArray(k2);
// Turns the bytes of the modified number into a DES key spec
DESKeySpec deskeyspec = new DESKeySpec(deskeydata);
// Makes a secret key (DES)
SecretKeyFactory keyF = SecretKeyFactory.getInstance("DES");
SecretKey keystuff = keyF.generateSecret(deskeyspec);
System.out.println(keystuff.toString());
// Gets an incoming string from the client and turns it into binary
byte[] incomingBytes = new byte[128];
try{
inFromClient.readFully(incomingBytes);
} catch(EOFException eof){
System.out.println("Finished reading");
}
System.out.println(new String(incomingBytes));
Cipher c = Cipher.getInstance("DES/CBC/PKCS5Padding");
// Decrypts the string using the shared secret key
c.init(Cipher.DECRYPT_MODE, keystuff, new IvParameterSpec(new byte[8]));
byte[] ct2 = c.doFinal(incomingBytes);
// Decode it from base 64
//byte[] decodedBytes = Base64.getDecoder().decode(ct2);
// Prints the received string
System.out.println("Received: " + new String(ct2));
inFromClient.close();
outToClient.close();
} catch(Exception e){
e.printStackTrace();
}
}
}
我的客户代码:
public static void main(String[] args) {
// Creates a socket to the local host on port 6789
Socket clientSocket = null;
try {
clientSocket = new Socket("localhost", 6789);
} catch (IOException e1) {
e1.printStackTrace();
}
try{
double k1, B, A;
double n = 13;
double g = 61;
long x = 3;
// Sends an unencrypted number to the server
A = (Math.pow(g, x))%n;
DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
DataInputStream inFromServer = new DataInputStream(clientSocket.getInputStream());
// Transforms A into a byte array and sends it over
outToServer.writeDouble(A);
outToServer.flush();
System.out.println("Sending " + A);
// Reads the incoming data from the server
B = inFromServer.readDouble();
System.out.println("Recieved " + B);
// Modifies the data to create the number for des key
k1 = (Math.pow(B, x))%n;
System.out.println("DES key seed = " + k1);
byte[] deskeydata = toByteArray(k1);
// Turns the bytes of the modified number into a DES key spec
DESKeySpec deskeyspec = new DESKeySpec(deskeydata);
// Makes a secret key (DES)
SecretKeyFactory keyF = SecretKeyFactory.getInstance("DES");
SecretKey keystuff = keyF.generateSecret(deskeyspec);
System.out.println(keystuff.toString());
// Takes in input from the user and turns it into binary
BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a message:");
String sentence = inFromUser.readLine();
byte[] str2 = sentence.getBytes();
byte[] encodedMessage = Base64.getEncoder().encode(str2);
Cipher c = Cipher.getInstance("DES/CBC/PKCS5Padding");
// Encrypts the user's input with the secret key
c.init(Cipher.ENCRYPT_MODE, keystuff, new IvParameterSpec(new byte[8]));
byte[] ct2 = c.doFinal(encodedMessage);
System.out.println("Initted the cipher and moving forward with " + new String(ct2));
// Writes the encrypted message to the user
outToServer.write(ct2);
outToServer.flush();
inFromServer.close();
outToServer.close();
} catch(Exception e){
e.printStackTrace();
}
}
任何可以帮助我完成这项工作的事情都会受到极大的欢迎,因为我已经在这段时间里独自处理这个错误。
答案 0 :(得分:0)
我设法找到了解决这个问题的方法(虽然我怀疑这是非常低效的)。问题是由于服务器端的readFully方法。我正在将答案读入一个128字节的数组,解密函数将字节数组中的空插槽视为一些东西而不是什么。
为了解决这个问题,我用以下内容替换了输入部分,它读取每个字节并创建一个字节数组,其中包含传入消息的确切长度。
<TextBox x:Name="TextBox1" Margin="16,16,16,49" TextWrapping="Wrap"
IsReadOnly="True" VerticalScrollBarVisibility="Auto" FontSize="12" />
<Slider x:Name="slider" HorizontalAlignment="Left" Margin="20,78,0,-1"
Width="166" Maximum="50" Minimum="12" Value="{Binding Path=FontSize, ElementName=TextBox1}" />