Sending data over sockets (Java to C)

Question

I am trying to send some encrypted integers between Java as client and C as Server, using symmetric key and here is the code .... The problem is that I can Not read the numbers or the integers!!!! I am using writeInt function on Java side to send the number of digits first to use it in a loop to encrypt/decrypt each number separately, then I use the symmetric key to encrypt/decrypt the whole number. Any idea how to make it work ?

This the java code:

public void sendData(int data) throws IOException
    {
        int dataInInt = data, numberOfDigits = 0;
        System.out.println("DATAININT =  " + dataInInt);
        while(dataInInt != 0)
        {
            dataInInt /= 10;
            numberOfDigits++;
        }
        dataInInt = data;

        System.out.println("Number of digits to be sent = " + numberOfDigits);
        dout.writeInt(numberOfDigits);


        int [] dataInDigits = new int [numberOfDigits];
        for (int j = (numberOfDigits - 1); j >= 0; j--)
        {
            dataInDigits[j] = dataInInt % 10;
            dataInInt /= 10;
        }


        int [] dataToSendInt = new int [numberOfDigits];
        for (int i = 0; i < dataToSendInt.length; i++)
        {
            dataToSendInt[i] = dataInDigits[i] ^ symmetricKeyInDigits[i % symmetricKeyInDigits.length];
            System.out.println("TOSEND = " + dataToSendInt[i]);
            dout.writeInt(dataToSendInt[i]);
        }
    }

This is the C side:

char *receiveData(int sock)
{   
    int counter = 0, i = 0, j = 0;
    char buffer[256];
    bzero(buffer, 256);

    int tempKey = symmetricKeyInt, KeyDigitsNumber = 0;
    while (tempKey > 0)
    {
        tempKey /= 10;
        KeyDigitsNumber++;
    }
    tempKey = symmetricKeyInt;

    int KeyArr[KeyDigitsNumber];
    for (j = KeyDigitsNumber - 1; j >= 0; j--)
    {
        KeyArr[j] = tempKey % 10;
        tempKey = tempKey / 10;
    }

    read(sock, buffer, 255);
    int bufferSize = ntohl(*((int*)&buffer))
    char *temp;
    char *decrypted = malloc(bufferSize);
    char numBuffer[20];
    int testInt;
    int encInt;

    for (j = 0; j < bufferSize; j++)
    {
        bzero(numBuffer, 20);
        read(sock, numBuffer, 19);
        testInt = ntohl(*((int*)&numBuffer)) ^ KeyArr[j %KeyDigitsNumber];
        sprintf(temp, "%d", testInt);
        decrypted[j] = temp;
    }
    printf("THis from inside receiveData function: %s\n", (char *)decrypted);
    return decrypted;
}

Answer 1

Instead of sending them as integers and using writeInt, rather send the integers as a string and convert them on either side. Also use a printWriter.