Skip to main content

MIRRORCROCODILE - a tool that helps to mess around with 433Mhz devices

I think the coolest thing to do with computers is to interact with the real world. Computers used to have parallel ports. Parallel ports made it super easy for tinkerers to interface with the real world. I have seen a lot of projects around parallel port but they are the thing of the past. New computers do not ship with parallel ports – nobody uses them – only people, who want to flash LEDs, when they receive a new email etc.

What is the next best thing? What is the thing that every computer has? USB is hard mess around because it is too advanced for simple projects. You need to use controllers and it gets complicated fast - at least for me.

So then, inspired from that triggertrap post I realized – SOUNDCARD. Every computer/phone has a headphone jack. But what happens if you want to listen to music and flash LEDs? Then you buy a cheap USB soundcard from eBay and use that as a platform (You do not want to fry your onboard soundcard, I think).

Soundcard is basically an ADC and a DAC (microphone and headphone jack).

So I had an idea to strap a 433 MHz transmitter and a receiver to the soundcard. In my head it played out like this :

  • You can record devices that use simple modulations (AM/OOK).

  • You can send signals from the computer(GNURadio).

  • You can use replay (transmit, what was received).

So this project needed a cool codename, NSA has l33t codenames so I came up with MIRRORCROCODILE courtesy of



2015-07-02 21.25.50

Mirror attack is the simplest, you only have to record and press play.

Here is a video, where I mimic my wireless doorbell signal. Technically it should work most of the 433 MHz devices that do not use rolling code or not use some other signal modulation.

Or if you want to edit/analyze the data more or even send out completely new stuff - GNURadio should be useful enough.




  1. can I get rf receiver ARDUINO code that u posted on summer 2014 under title "Sending and receiving data using 433mhz "


Post a Comment

Popular posts from this blog

My take on a nixie clock

As a present I decided to build a nixie tube clock. It was essential to ditch my close-enough attitude and make it look as good as possible. For me the simplest way to complete this idea was to use a microcontroller. I am not cool enough to build a clock out of discrete logic, maybe in the future.

I had couple of nixie tubes lying around, I ordered some more to have a total of six. So the clock consist of an Arduino Nano, RTC DS3231, nixie tubes - IN-14 and a power supply. From the start I knew the biggest challenge is building the enclosure. I learned that the easiest way to drive these nixie tubes is with a driver called - К155ИД1.

It’s a binary to decimal decoder and it works quite elegantly. Depending on the binary input it enables the right output.

It does all the heavy lifting. And then I used three shift registers to drive all the drivers.

In addition I bought a nixie tube power supply that supplies the 170v I need. I could have used 220v wall power but I do not trust myself enou…

My take on the PA0RDT Mini Whip antenna.

I like shortwave radio because you can receive signals from all over the world, also there are all kinds of mysterious signals to explore.

In the grand scheme - the lower the frequency, the bigger antenna you would need. Well, there are all kinds of antenna designs but I like to think like that way. For example, I have a 27 MHz dipole on my roof that is around 5.3 meters long. If I wanted to listen to lower frequencies ~ around 3 MHz, for optimal performance I would need around 50 meter antenna, so using dipole for lower frequencies is not very space efficient, especially if you do not have any room.

So I decided to build the Mini Whip antenna. It is popular, simple to build and on paper receives frequencies from 10 kHz to 30 MHz, and also it is super tiny.

There are some variations between different designs, but the basic idea is the same.

The schematic I followed.

During my tests it performed well, I was able to receive DCF77 signal for the first time. All other bands seemed to work as w…

RFID experiments

Radio-frequency identification (RFID) is a way to use electromagnetic fields to send and receive data wirelessly. The system consists of two parts: reader and a tag.  Tags can be passive or active. I think the most popular are passive tags. Meaning, there are no batteries needed, the power comes from the reader. The reader constantly sends out an interrogation signal and when a tag absorbs the energy and powers up, it radiates back information from the embedded chip.

Then it divides further - different frequencies, generations, encryptions etc.

Also one popular part is NFC (Near Field Communication) which has better security and other improvements. Latest phones usually come with NFC read/write capabilities built in.  So you can pay with your phone or touch phones together to share information. A lot of possibilities.

RFID/NFC is quite popular in our commercial world.

Anti-theft – stores use it to stop people stealing stuff.
Tracking people - putting tags inside shoes to track people, some…