Python PyBluez connecting to passkey protected device

Question

I'm working on an application in Python (currently 2.7, can switch to 3.3 if necessary) that is supposed to:

Detect bluetooth device (finger clip pulse oximeter, if you're interested).
Establish connection with device (which is passkey protected)
Stream data from the device to my computer
Do more (currenly irrelevant) programming with the data

To accomplish this, I'm using the PyBluez library for Python, as it is probably the most documented library I've found (which sadly is still quite little) that is compatible with Windows and Python2.7.

I am very new to socket programming, so this is probably a simple question. The issue I've encountered, is that I cannot seem to figure out how to connect to the device since it is passkey protected. I can locate it and retrieve its address with no problem, I just don't know what port to use when connecting or how to enter a passkey.

Thanks for your help!

Reference Information:
Pulse oximeter used: http://www.echostore.com/wireless-oximeter-cms50e.html
PyBluez library: http://pybluez.googlecode.com/svn/www/docs-0.7/index.html

score 0 · Answer 1 · answered Aug 27 '13 at 07:54

I meet the same problem,and I have resolved the problem, Maybe you can try it:

make a windows tool named pairtool.exe, it help you to pairing with command line.

dwRet = BluetoothAuthenticateDevice(NULL, NULL, &btdi, L"1234", 4);
if(dwRet != ERROR_SUCCESS)
{
    fprintf(stderr, "BluetoothAuthenticateDevice ret %d\n", dwRet);
    ExitProcess(2);
}

python code:

def connect2Btdev(devName):
#found the device addr
addr = inquiry(devName)
if addr == None:
   return None

#pairing with pairtool.exe
cmd=r'%s %s' % ('pairtool.exe',addr)
ret = os.system(cmd)

if ret <> 0:
    return None

score 0 · Answer 2 · edited May 23 '17 at 11:57

PyBlueZ does not expose the windows Bluetooth authentication APIs here: https://msdn.microsoft.com/en-us/library/windows/desktop/cc766819(v=vs.85).aspx

One way to get around this is to create a command line tool and use this through Python. To create command line tools for Windows, use Visual Studio and add the necessary libraries to your project linker properties: Bthprops.lib and ws2_32.lib

Below is the code for a project to make a command line tool with 1 parameter, the MAC address, that pairs the specified device using "Just Works" pairing. See commented code for using passkey pairing.

#include "stdafx.h"
#include <initguid.h>
#include <winsock2.h>
#include <BluetoothAPIs.h>
#include <ws2bth.h>

BOOL WINAPI BluetoothAuthCallback(LPVOID pvParam, PBLUETOOTH_AUTHENTICATION_CALLBACK_PARAMS pAuthCallbackParams);

int _tmain(int argc, _TCHAR* argv[])
{
    SOCKADDR_BTH sa = { 0 };
    int sa_len = sizeof(sa);
    DWORD dwRet;
    BLUETOOTH_DEVICE_INFO  btdi = { 0 };
    HBLUETOOTH_AUTHENTICATION_REGISTRATION hRegHandle = 0;

    // initialize windows sockets
    WORD wVersionRequested;
    WSADATA wsaData;
    wVersionRequested = MAKEWORD(2, 0);
    if (WSAStartup(wVersionRequested, &wsaData) != 0) {
        ExitProcess(2);
    }

    // parse the specified Bluetooth address
    if (argc < 2) {
        fprintf(stderr, "usage: csbtpair <addr>\n"
            "\n  addr must be in the form (XX:XX:XX:XX:XX:XX)");
        ExitProcess(2);
    }
    if (SOCKET_ERROR == WSAStringToAddress(argv[1], AF_BTH,
        NULL, (LPSOCKADDR)&sa, &sa_len)) {
        ExitProcess(2);
    }

    // setup device info
    btdi.dwSize = sizeof(BLUETOOTH_DEVICE_INFO);
    btdi.Address.ullLong = sa.btAddr;
    btdi.ulClassofDevice = 0;
    btdi.fConnected = false;
    btdi.fRemembered = false;
    btdi.fAuthenticated = false;

    // register authentication callback. this prevents UI from showing up.
    dwRet = BluetoothRegisterForAuthenticationEx(&btdi, &hRegHandle, &BluetoothAuthCallback, NULL);
    if (dwRet != ERROR_SUCCESS)
    {
        fprintf(stderr, "BluetoothRegisterForAuthenticationEx ret %d\n", dwRet);
        ExitProcess(2);
    }

    // authenticate device (will call authentication callback)
    AUTHENTICATION_REQUIREMENTS authreqs = MITMProtectionNotRequired;
    fprintf(stderr, "BluetoothAuthReqs = %d\n", authreqs);
    dwRet = BluetoothAuthenticateDeviceEx(NULL, NULL, &btdi, NULL, authreqs);
    if (dwRet != ERROR_SUCCESS)
    {
        fprintf(stderr, "BluetoothAuthenticateDevice ret %d\n", dwRet);
        if (dwRet == ERROR_CANCELLED)
        {
            fprintf(stderr, "Cancelled");
        }
        else if (dwRet == ERROR_INVALID_PARAMETER)
        {
            fprintf(stderr, "Invalid Parameter");
        }
        else if (dwRet == ERROR_NO_MORE_ITEMS)
        {
            fprintf(stderr, "Already paired!");
        }
    }

    fprintf(stderr, "pairing finish\n");
    ExitProcess(0);
    return 0;
}

// Authentication callback
BOOL WINAPI BluetoothAuthCallback(LPVOID pvParam, PBLUETOOTH_AUTHENTICATION_CALLBACK_PARAMS pAuthCallbackParams)
{
    DWORD dwRet;

    fprintf(stderr, "BluetoothAuthCallback 0x%x\n", pAuthCallbackParams->deviceInfo.Address.ullLong);
    BLUETOOTH_AUTHENTICATE_RESPONSE AuthRes;
    AuthRes.authMethod = pAuthCallbackParams->authenticationMethod;
    fprintf(stderr, "Authmethod %d\n", AuthRes.authMethod);
    // Check to make sure we are using numeric comparison (Just Works)
    if (AuthRes.authMethod == BLUETOOTH_AUTHENTICATION_METHOD_NUMERIC_COMPARISON) 
    {
        fprintf(stderr, "Numeric Comparison supported\n");
    }
    AuthRes.bthAddressRemote = pAuthCallbackParams->deviceInfo.Address;
    AuthRes.negativeResponse = FALSE;

    // Commented out code is used for pairing using the BLUETOOTH_AUTHENTICATION_METHOD_PASSKEY method
    //memcpy_s(AuthRes.pinInfo.pin, sizeof(AuthRes.pinInfo.pin), L"1234", 0);
    //AuthRes.pinInfo.pinLength = 0;
    // Respond with numerical value for Just Works pairing
    AuthRes.numericCompInfo.NumericValue = 1;

    // Send authentication response to authenticate device
    dwRet = BluetoothSendAuthenticationResponseEx(NULL, &AuthRes);
    if (dwRet != ERROR_SUCCESS)
    {
        fprintf(stderr, "BluetoothSendAuthenticationResponseEx ret %d\n", dwRet);
        if (dwRet == ERROR_CANCELLED)
        {
            fprintf(stderr, "Bluetooth device denied passkey response or communicatino problem.\n");
        }
        else if (dwRet == E_FAIL)
        {
            fprintf(stderr, "Device returned a failure code during authentication.\n");
        }
        else if (dwRet == 1244)
        {
            fprintf(stderr, "Not authenticated\n");
        }
    }
    else
    {
        fprintf(stderr, "BluetoothAuthCallback finish\n");
    }

    return 1; // This value is ignored
}

In lieu of creating this yourself, you may want to try this pre-made solution: http://bluetoothinstaller.com/bluetooth-command-line-tools/ It did not work for my particular solution.

Then, you will need to run your downloaded or custom command line tool from python as an administrator. To do this reliably, I recommend the stackoverflow question: How to run python script with elevated privilege on windows

Python PyBluez connecting to passkey protected device

2 Answers2

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