Kushal Das

FOSS and life. Kushal Das talks here.


My talk in RustNL 2023

starting of the conference

On May 10th, I attended my first ever Rust conference, RustNL 2023. I reached there the night before. My talk was the 3rd one in the morning.

My talk

The title of my talk was Using Rust to write Python modules, and my main plan was to inform developers in the crowd to think about python developers as their API/library users. I demoed Tumpa to showcase what can be achieved to help the final end users.

The next 2 talks after mine also had Python in the theme. You should check out all the talks from the conference.

Book signing queue

I also managed to meet Mara Bos and get a copy of the book signed. Thank you so much.

I found the conference very tightly organized. The venue being on top of a library and centrally located was also very useful. The funniest incident was to find milk in the lunch menu, that was a first for me.

I also managed to meet some friends whom I only knew from Internet and met other Fedora friends after around 8 years.

I am hoping to be able to participate next year too.

Tumpa 0.10.0 is ready

I am happy to announce Tumpa 0.10.0 release. Tumpa is a desktop application which allows you to create OpenPGP keys and also allows uploading them to Yubikeys with a user friendly GUI. With Tumpa, all you need is a few form inputs and few clicks, and done! No more wrangling and breaking your head with command line interface.


This version is a complete rewrite of the initial version I released around 2 years ago. With the help from Elio and his excellent team, we have a new design. Thank you OTF for providing the funding for the work.

Saptak & I decided that the code is ready to be consumed. There are still things to work on, including the UI flows. In the coming months we are going to add more features to the application to make it super useful for advanced users too.

You can create Cv25519 or RSA4096 keys via the "Generate Key" button. You can upload any key to an attached Yubikey, but remember that to use a Cv25519 key, you will need Yubikey 5.

Showing all avaialble keys


For Linux we have an AppImage and for Apple M1/M2 devices we have a dmg. You can download them from the release page. Remember to have a look at the user guide, specially because you need to have pcscd service running on Linux.

Upload successful

Technologies used

This project works because we have Johnnycanencrypt , a Python module written in Rust to do OpenPGP operations (including Smartcard operations). Which in turn uses Sequoia Project for the rust library to create/manipulate OpenPGP keys.

The UI is made via QML, using PySide6. This also shows that we can have decent looking desktop applications in Python.

The AppImage and Apple dmg files are available because of briefcase project from BeeWare team.

Give feedback

Since the focus of Tumpa is on making the use of OpenPGP with smart cards user friendly and intuitive, we need a lot of feedback from the user. So, if you find issues and have other feedback to improve the application, feel free to submit [issues])(https://github.com/tumpaproject/tumpa/issues). We are also available in #tumpa channel on IRC on libera.chat server. Feel free to ping the IRC nicknames saptaks or kushal.

Introducing Tugpgp

At Sunet, we have heavy OpenPGP usage. But, every time a new employee joins, it takes hours (and sometime days for some remote folks) to have their Yubikey + OpenPGP setup ready.

Final screen

Tugpgp is a small application built with these specific requirements for creating OpenPGP keys & uploading to Yubikeys as required in Sunet. The requirements are the following:

  • It will create RSA 4096 Key
  • There will be a primacy key with Signing & Certification capability.
  • There will be an encryption and one authentication subkey.
  • All keys have 1 year expiry date.
  • During the process the secret key will not be written to the disk.
  • Encryption & signing has touch policy fixed in the Yubikey (it can not be changed).
  • Authentication has touch policy on (means it can be turned off by the user).
  • The OTP application in the Yubikey will be disabled at the end.

We have an Apple Silicon dmg and AppImage (for Ubuntu 20.04 onwards) in the release page. This is my first ever AppImage build, the application still needs pcscd running on the host system. I tested it on Debian 11, Fedora 37 with Yubikey 4 & Yubikey 5.

Oh, there is also a specific command line argument if you really want to save the private key :) But, you will have to find it yourself :).

demo gif

If you are looking for the generic all purpose application which will allow everyone of us to deal with OpenPGP keys and Yubikeys, then you should check the upcoming release of Tumpa, we have a complete redesign done there (after proper user research done by professionals).

Creating password input widget in PyQt

One of the most common parts of writing any desktop tool and taking password input is about having a widget that can show/hide password text. In Qt, we can add a QAction to a QLineEdit to do the same. The only thing to remember, that the icons for the QAction, must be square in aspect ratio; otherwise, they look super bad.

The following code creates such a password input, and you can see it working at the GIF at the end of the blog post. I wrote this for the SecureDrop client project.

class PasswordEdit(QLineEdit):
    A LineEdit with icons to show/hide password entries
    CSS = '''QLineEdit {
        border-radius: 0px;
        height: 30px;
        margin: 0px 0px 0px 0px;

    def __init__(self, parent):
        self.parent = parent

        # Set styles

        self.visibleIcon = load_icon("eye_visible.svg")
        self.hiddenIcon = load_icon("eye_hidden.svg")

        self.togglepasswordAction = self.addAction(self.visibleIcon, QLineEdit.TrailingPosition)
        self.password_shown = False

    def on_toggle_password_Action(self):
        if not self.password_shown:
            self.password_shown = True
            self.password_shown = False

PyQt5 thread example

PyQt is the Python binding for Qt library. To write Qt5 code, we use PyQt5 module. Like many others, my first introduction to GUI application development was using PyQt. Back in foss.in 2005 a talk from Sirtaj introduced me to PyQt, and later fall in love with it.

I tried to help in a GUI application after 8 years (I think), a lot of things have changed in between. But, Qt/PyQt still seems to be super helpful when it comes to ease of development. Qt has one of the best documentation out there for any Open Source project.

Many students start developing GUI tools by replacing one of the command line tool they use. Generally the idea is very simple, take some input in the GUI, and then process it (using a subprocess call) on a button click, and then show the output. The subprocess call happens over a simple method, means the whole GUI gets stuck till the function call finishes. We can fix this issue by using a QThread. In the below example, we will just write a frontend for git clone command and then will do the same using QThread.

Setting up project directory

I have used qt creator to create a simple MainWindow form and saved it as mainwindow.ui in the project directory. Then, used pipenv to create a virtualenv and also installed the pyqt5 module. Next, used the pyuic5 command to create a Python file from UI file.

The code does not have error checks, the subprocess documentation should give you enough details about how to add them.

Doing git clone without any thread

The following code creates a temporary directory, and then git clones any given git repository into that.


import sys
import tempfile
import subprocess
from PyQt5 import QtWidgets

from mainwindow import Ui_MainWindow

class ExampleApp(QtWidgets.QMainWindow, Ui_MainWindow):

    def __init__(self, parent=None):
        super(ExampleApp, self).__init__(parent)
        # Here we are telling to call git_clone method when
        # someone clicks on the pushButton.

    # Here is the actual method which does git clone
    def git_clone(self):
        git_url = self.lineEdit.text()  # Get the git URL
        tmpdir = tempfile.mkdtemp()  # Creates a temporary directory
        cmd = "git clone {0} {1}".format(git_url, tmpdir)
        subprocess.check_output(cmd.split())  # Execute the command
        self.textEdit.setText(tmpdir)  # Show the output to the user

def main():
    app = QtWidgets.QApplication(sys.argv)
    form = ExampleApp()

if __name__ == '__main__':

Doing git clone with a thread

In the below example we added a new CloneThread class, it has a run method, which gets called when the thread starts. At the end of the run, we are emitting a signal to inform the main thread that the git clone operation has finished.


import sys
import tempfile
import subprocess
from PyQt5 import QtWidgets
from PyQt5.QtCore import QThread, pyqtSignal

from mainwindow import Ui_MainWindow

class CloneThread(QThread):
    signal = pyqtSignal('PyQt_PyObject')

    def __init__(self):
        self.git_url = ""

    # run method gets called when we start the thread
    def run(self):
        tmpdir = tempfile.mkdtemp()
        cmd = "git clone {0} {1}".format(self.git_url, tmpdir)
        # git clone done, now inform the main thread with the output

class ExampleApp(QtWidgets.QMainWindow, Ui_MainWindow):

    def __init__(self, parent=None):
        super(ExampleApp, self).__init__(parent)
        self.pushButton.setText("Git clone with Thread")
        # Here we are telling to call git_clone method when
        # someone clicks on the pushButton.
        self.git_thread = CloneThread()  # This is the thread object
        # Connect the signal from the thread to the finished method

    def git_clone(self):
        self.git_thread.git_url = self.lineEdit.text()  # Get the git URL
        self.pushButton.setEnabled(False)  # Disables the pushButton
        self.textEdit.setText("Started git clone operation.")  # Updates the UI
        self.git_thread.start()  # Finally starts the thread

    def finished(self, result):
        self.textEdit.setText("Cloned at {0}".format(result))  # Show the output to the user
        self.pushButton.setEnabled(True)  # Enable the pushButton

def main():
    app = QtWidgets.QApplication(sys.argv)
    form = ExampleApp()

if __name__ == '__main__':

The example looks like the above GIF. You can find the source code here. You can find a bigger example in the journalist_gui of the SecureDrop project.

pony 0.4 released

I just released Pony 0.4 into the wild. It came out with a 2 days delay :(

Pony is a KDE based image manager. The main feature is to create Collections out of removable devices and watch/search the thumbnails offline (when the media is not attached). New features in this release:

  • shortcut key 'u' to get the upload to flickr dialog
  • Hot keys: Now one can assign hotkeys using numeric key board , right now only %f (selected filename) is supported there.

Download the source or you can use this yum repo for Fedora 11.

The post is brought to you by lekhonee v0.7

translation-filter 1.0 released

A massive jump in the release number and now we have translation-filter 1.0 :) Download the source from here. What is translation-filter ? It is a tool to imporve l10n quality by helping in finding different corner cases. This is being developed as a part of aukur.org.in . It is having two GUI(s), one Gnome and one for KDE and a command line version. Couple of the features are only available in the command line version. Different features of translation-filter:

  • It can search for word(s) in a given directory or some selected files. The result will be saved as an HTML file or can also be seen in the command line. By using this features one can check consistency of usage
  • It can create single word based list from the given .po files. It will contain both the term and translated string(s)
  • It can check for any unattached dependent vowel sign. Right now it can find that for the Indic languages. Like ি and া can not sit beside

To know more about different options read here.

The post is brought to you by lekhonee v0.6

Pony v0.3 released

I just released Pony v0.3 , you can download the source from here. Pony is an image manager written in PyKDE4.
If you are using a previous version of pony , you should remove the old db by $rm ~/.pony.db

This release is having many bug fixes and also new features.


  • One can create media catalog (DVD or removable medias)
  • Search media catalogs based on tags
  • Flickr image uploading is now smoother
  • While in FullScreen image viewing one can use mouse whell to browse through images

Here is a preview of the new catalog options

Pony v0.3

If you are using Fedora 11 , you can add my repo as building and pushing to the Fedora repos may take some time. To do so just drop this in your /etc/yum.repos.d/

The post is brought to you by lekhonee v0.6

New release of lekhonee

I am happy to release lekhonee-0.3.1

New release of lekhonee

lekhonee is a desktop client for Wordpress. The new features of this release are:

  • Add Category
  • Spell Check enable/disable
  • Edit last entry

I never blogged about a few last releases, I moved the codebase to PyKDE4. It is using KWallet service to store the password. If you don't want to use kwallet (like you are a gnome user), it will ask you to type-in the details every time.

Download tarball, F-10 rpm (pushed to stable), F-11 rpm