Securing php api to use in android application

I am newbie to android development. I am using android studio for developing an application. Things i have done

1. Created a DB with two tables in it in MySQL.
2. Created two separate api's for both GET and POST methods.
3. Successfully accessed both api's

What i have achieved for now

1. Able to GET data form the GET api.
2. Able to POST data using the POST api

What i have to do now

I want my api to publish online, i.e. I want to deploy my services into a server and access them. At this point i am able to deploy the services on the server and accessed them.

Now i want my services(api's) to be secured. For that i have searched many articles and found two ways.

1. Use yii framework. Someone told me to use it because it automatically secured the api's. But i don’t know for sure whether it do or not.
2. Manually secure the api's

As for point 1 the framework will be helpful but it’s new to me and it will take time to coop with it as i am already created the web services.

For point 2 i got some information

1. using HMAC_SHA1
2. DETECTING MOBILE DEVICES USING PHP

Both links seems to be good but link 1 doesn’t gives me much info on that.

Obviously i want to secure my both api's

Now the code part

GET_DATA.php

require_once ('config.php');

$sql = "SELECT * FROM users";


$r = mysqli_query($con,$sql);

$result = array();

while($row = mysqli_fetch_array($r)){
array_push($result,array(
    'Id'=>$row['Id'],
    'Name'=>$row['Name']
));}

echo json_encode(array(‘users’=>$result));

POST_DATA.php

require_once ('config.php');

$return_arr = array();

$UserId=($_POST['UserId']);
$Latitude=($_POST['Latitude']);
$Longitude=($_POST['Longitude']);
$DateTime=($_POST['DateTime']);


$user_register_sql1 = "INSERT INTO `activity`(`Id`,`UserId`, `Latitude`,`Longitude`,`DateTime`) values (NULL,'".$UserId."','".$Latitude."','".$Longitude."','".$DateTime."')";
mysqli_query ($con,$user_register_sql1);
$row_array['errorcode1'] = 1;

I have a user class from which i am getting username and ID

JSONfunctions.java

This class is responsible for getting data from the api

 public static JSONObject getJSONfromURL(String url)
{

    String json = "";
    JSONObject jsonObject = null;
    try
    {
        HttpClient httpClientt = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(url);
        HttpResponse httpResponse = httpClientt.execute(httpGet);
        BufferedReader br = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent()));
        StringBuffer sb = new StringBuffer();
        String line = "";
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

        json = sb.toString();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try
    {
        jsonObject = new JSONObject(json);
    } catch (JSONException e) {
        e.printStackTrace();
    }

    return jsonObject;
}

PutUtility.Java

This class is responsible for POST method

public void setParam(String key, String value) {
    params.put(key, value);
}

public String postData(String Url) {

    StringBuilder sb = new StringBuilder();
    for (String key : params.keySet()) {
        String value = null;
        value = params.get(key);


        if (sb.length() > 0) {
            sb.append("&");
        }
        sb.append(key + "=" + value);
    }

    try {
        // Defined URL  where to send data

        URL url = new URL(Url);

        URLConnection conn = null;
        conn = url.openConnection();

        // Send POST data request
        httpConnection = (HttpURLConnection) conn;
        httpConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        httpConnection.setRequestMethod("POST");
        httpConnection.setDoInput(true);
        httpConnection.setDoOutput(true);
        OutputStreamWriter wr = null;

        wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(sb.toString());
        wr.flush();

        BufferedReader in = new BufferedReader(
                new InputStreamReader(httpConnection.getInputStream()));
        String inputLine;
        response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        try {
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    return response.toString();
}

MainActivity.java

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    _latitude = (TextView)findViewById(R.id.latitude);
    _longitude = (TextView)findViewById(R.id.longitude);
    btn_get_coordinates = (Button)findViewById(R.id.button);
    btn_save_data = (Button)findViewById(R.id.btn_save);   


    btn_save_data.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if(UserId.toString()== "" || Latitude.toString() == "" || Longitude.toString() == "" || DateTime.toString() == "")
            {
                Toast.makeText(getApplicationContext(), "Data Not Saved !!!! Please select appropriate data to save", Toast.LENGTH_SHORT).show();
            }


            new ServiceLogin().execute(UserId, Latitude, Longitude, DateTime);

        }
    });

    // Download JSON file AsyncTask
    new DownloadJSON().execute();
}
    // Download JSON file AsyncTask
private class DownloadJSON extends AsyncTask<Void, Void, Void>
{

   @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = new ProgressDialog(MainActivity.this);
        progressDialog.setMessage("Fetching Users....!");
        progressDialog.setCancelable(false);
        progressDialog.show();

    }

    @Override
    protected Void doInBackground(Void... params) {

        // Locate the Users Class
        users = new ArrayList<Users>();

        // Create an array to populate the spinner
        userList = new ArrayList<String>();
        // http://10.0.2.2:8000/MobileApp/index.php
        //http://10.0.2.2:8000/app/web/users/
        //http://192.168.100.8:8000/app/web/users/
        // JSON file URL address
        jsonObject = JSONfunctions.getJSONfromURL("http://192.168.100.9:8000/MobileApp/GET_DATA.php");

        try
        {
            JSONObject jobj = new JSONObject(jsonObject.toString());
            // Locate the NodeList name
            jsonArray = jobj.getJSONArray("users");

            for(int i=0; i<jsonArray.length(); i++)
            {
                jsonObject = jsonArray.getJSONObject(i);

                Users user = new Users();

                user.setId(jsonObject.optString("Id"));
                user.setName(jsonObject.optString("Name"));
                users.add(user);

                userList.add(jsonObject.optString("Name"));

            }
        } catch (JSONException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }


        return null;
    }

    @Override
    protected void onPostExecute(Void args)
    {
        // Locate the spinner in activity_main.xml
        Spinner spinner = (Spinner)findViewById(R.id.spinner);

        // Spinner adapter
        spinner.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_spinner_dropdown_item, userList));

        // Spinner on item click listener

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {


            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

                textViewResult = (TextView)findViewById(R.id.textView);

                // Set the text followed by the position

                textViewResult.setText("Hi " + users.get(position).getName() + " your ID is " + users.get(position).getId());
                UserId = String.valueOf(users.get(position).getId());
                progressDialog.dismiss();
                _latitude.setText("");
                _longitude.setText("");
                Latitude = null;
                Longitude= null;

            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                textViewResult.setText("");
            }
        });
    }


}

As i am newbie, so i don’t know what to do in php script and what to do in my android code :(. It would be very helpful if anyone can guide me or give me a tutorial that i follow.

Any help would be highly appreciated.

Answer

To secure your APIs, you need a mechanism to detect that the request to the api is made from a trusted source. Many frameworks come with this feature by default.

However you can just use JSON Web Tokens (jwt) with PHP to add authorization to your api requests

Learn about token based authentication from this page.

Check out this simple tutorial on how to secure your PHP api endpoints with JWT.

If you need even more security you might want to add OAuth provider service to your API. check out this post on how to write OAuth provider in PHP