Crypto bot

Recently I’ve been following the crypto market, which is very fascinating to me. I’ve subscribed to kraken, a popular exchange and put some money in it. After a service outage in the middle of january, kraken’s team decided to cut the transactions fees for a while, thus I took the opportunity to code and test a from-scratch crypto-trader bot.

I have no time to get into details, also because they are not so much interesting or particularly complex, but I’ll say that it uses a combination of some simple and common algorithms widely used in the study of the financial market. The bot actually works, in the sense that it makes trades on some deterministic rules, but unfortunately it is not clever enough to make profit (even without the fees) and barely breaks even.

Anyway, as always, it’s been very fun and instructive to code, as I had to study and learn how the market behaves, how to handle the market data and how to try to predict trends and accordingly set sell/buy points.

Since I’m not posting the code (yet), here’s its debug window:
cryptobot_best

NotesLearn

I recently bought an alto saxophone. It was quite a while I haven’t seriously been playing an instrument, so I came across a little challenge when it was time to read a music sheet. You know, that thing with a pentagram and some notes of various shapes drawn over it.

Since playing a note on the saxophone is not straightforward as it would be on a piano, I actually had two separate challenges: the first was to recognize a note on the pentagram, the second was to play it well (it means play the correct note steadly for some seconds – and in tune).

So I decided to code a little app to aid me doing so. The app is pretty simple: it shows a (random) note on the pentagram, and then listens to the microphone waiting for a note, identifying the pitch and, after some seconds of playing, says if the played note was correct or not. This app has proven quite useful in the process of improving my reading accuracy and speed, and I guess it might be useful to someone else too.

It’s published here: https://dmnk.cloud/noteslearn.

Technical infos

On the technical side, it is entirely coded using Javascript, and has been a cool challenge to code since it was the first time for me interacting with the microphone data on a web app. It uses some advanced Audio features of HTML5, based on the AudioContext component. Recognizing the pitch was a minor issue, obtained by playing a bit with the FFT of the signal, some other challenges included volume thresholding and octave recognition (less trivial).

In the end, the result is pretty usable for my alto sax, even though it may be less accurate if used with other instruments I didn’t test. The piano version is not perfect, for some notes it needs to repeatedly play the key to make the app recognize it. I guess it should work best with constant-volume-notes kind of instruments, like violin or flute, but as I said it was only fully tested with my alto sax.

KangaMex

Hello everyone! It’s been a while since I last wrote a piece on this blog, since that a lot of things changed, but I still want to share some of my experiences with the world.

I’ll be making some brief posts to track some projects I’ve been working to in these almost 2 years of absence.

This post is about KangaMex, a messaging platform which idea is really simple, yet I didn’t find something like it when I needed it. The app is a delayed messaging service, or a service to send messages which will be delivered only at a specified date and time in the future. You write your message, set the unlock date and time, the recipient’s username, and send it. The recipient will be notified that he/she has an upcoming message, but will not be able to see it until the unlock time has come. Very simple, nice way to send delayed messages.

The app is at mex.kanga.life.

Who wants to be millionaire?

You probably know the tv show “Who wants to be a millionaire”. Lately I’ve been invited at the graduation party of a friend, and thought about creating a game for it.

So I decided to create a HTML5 simulation of WWTBAB, complete with webcam support, sounds and introduction video. It has been quite fun, and I’ve been releasing the code on github.

Questions are hardcoded in the index.html file, but it’s trivial to modify them. Recently I’ve added support for images in questions.

I really don’t know if someone can actually make use of it, but who knows?

Just a quick overview about the keys used to control the simulation:

  • [Left arrow] – to skip to next step (video is not skippable by now)
  • [Down arrow] – to unveil the next answer
  • [A,B,C,D] – to highlight the selected answer
  • [Y,N] – when an answer is highlighted, Y makes it correct, N makes it wrong
  • [F] – to switch between the default background or the webcam image
  • [P] – to flash the background to induce some suspance

Github.

Example-link.

A try for a 3D game

Recently I’ve been experimenting a lot with 3D in the browser with Three.js, and although this is my first post about it, there’s a lot more I’m working on about 3D in JS, but it’s involved in my professional work and it’s not time to publish it yet.

Anyway, as usual I like to keep track of my projects here, so I link to this simple game I developed as a joke for a friend some days ago. The game is here, descriptions are in italian but if you don’t understand just click and everything will be fine.

Google Jam of Code

This is the second year I try to have some fun with python and the Google Code Jam.

This year I almost forgot about it, and started the challenge when almost half of the time was gone. Anyway I managed to complete almost half of the problems, which seemed pretty good to me, given that I spent just a few hours trying.

Unfortunately, my last attempt timed out by 3 minutes (out of 8 available) when trying to compute the result, which later proved correct. This reminded me about the importance of performance in my code: a little optimization of the code after my try gave it a speedup of 3x, which would have been enough to submit the result in time.

Anyway, both this and the last year I qualified for the second round. Last year I didn’t pass it, this year I hope to do better.

 

googlecodejam2015

JSMol plugin vulnerability and thoughts about security

JMol is a library used to create 3D models of molecules in Java, which can be embedded into webpages using the usual applets. JSMol is a Javascript library which is used to provide the Jmol capabilities through the HTML5 technologies, relying on server side computation for some functionality.

Here’s a short story about how I discovered some pretty bad vulnerabilities in the JSMol software, and how it can affect every server which is hosting this software.

 

Using my university’s moodle installation, I discovered that the JMol/JSMol plugin for moodle was installed and probably misconfigured in some way: it had unusual permissions set in its directory tree.

This made me curious and I wanted to better understand what was going on.

I made some research, and discovered the plugin along with its source code (the project is entirely open source), and started to look at the source of the only PHP file in the JSMol package.

Looking through the code, I discovered a lot of parameters used without proper sanitizing and checks, and quickly discovered two related and pretty serious vulnerabilities.

The first one is a vulnerability which allows an attacker to read the entire filesystem with the PHP process’ privileges. The second is even worse, but it seems it had been fixed in the newer releases of the software, and was about arbitrary execution of commands on the server.

They derived from an insecure use of PHP’s file_get_contents() and exec() functions in combination with badly checked parameters coming from GET and POST variables.

I immediately contacted the developer of the plugin and reported the vulnerability, along with the curator of the JMol plugin of moodle.

As of today, the vulnerability has been fixed by the developer, and should be available in the latest version of the software.

Anyway, some research I’ve made suggests that the vulnerability was present in many websites using the plugin, which I thinks are unlikely to upgrade the software. In particular I analyzed every registered moodle installation from moodle.net (roughly 50k) and discovered that a small fraction (~100) had the plugin installed and was vulnerable.

I would not classify it as a widespread vulnerability, but I think this should remind us of the nature of websites’ security. In fact, I would say that every even small piece of software publicly accessible on a website should be cause of concern when thinking about security.

As is often said, the best thing to do about software security is to firmly believe that you don’t have any.