Software
To be able to read QR codes we set up to write our own software making use of Python and open source
libraries.
Our final software encompasses multiple functions as we adapted it through the development of our project. In
simple terms, our scripts allow the user to perform the following functions:
- Generate a QR code from a message
- Encrypt the message within the QR code with a password
- Read the QR code
- Decrypt an encrypted QR code
- Generate a 3D model of a QR code to stamp on an agar plate
- Generate “gcode” based on a QR code to control a bioprinter to print a QR code
This method allows us to have more flexibility, and gives us the opportunity to optimize our program to our
desired settings, as other publicly available QR code tools may not be able to.
This section of our wiki is designed to provide the reader a better idea of how QR code technology works,
how
we
have designed our software to fit with our goals of privacy and security, and how our software allows all
these
tasks to be performed. First of all, a brief description of QR codes and how they encode data is outlined.
Then
the processes of our designed encryption and decryption mechanisms are explained.
An introduction to QR codes
QR codes operate by storing information in bytes, that is, blocks of zeros and ones that represent a
character.
However, the area of the QR code also contains further information such as:
- Error Correction data: that would allow the code, in case of damage, to still display its
information.
- Positioning data: these are the iconic three big squares in the corners that allow the camera to
determine where all other data points are.
- Format information: which tells the software what sort of information is stored in the QR code
(text, images…)
Different Sections in a QR code and their purpose (source: Datagenetics)
These codes have found their use in multiple applications, among which:
- Advertisement: to let people reach a link without typing it in
- Contact details: in business cards allows for quicker sharing of information
- Manufacturing lines: as they were originally created to track parts in a production line
- And many more fields! Keep your eyes open and you will see them in a day to day basis.
Encoding and Encryption Process
Before the data can be put into our petri dish we must first process it with the following steps:
- Encryption: using an algorithm to turn our message into a code that cannot be read, unless the user has
access to the password.
- Encoding: Putting the previously encrypted message into QR code format
The encryption process consists of feeding a set of characters into an algorithm that will output a
seemingly
random set of characters. This process is done with the military standard AES (Advanced Encryption Standard)
to ensure the best possible encryption levels. As an example, using the password “IGEM”, on the message
“QRoningen” outputs:
“ViJ1Z/mUu3rpoUdik2+ZUczyQV864zg+uinrjeZ6d+s=”
The encrypted QR code with the encrypted message (Go ahead, scan it!)
Encryption, however, is not a simple task. There are always third parties trying to break the methods or
find workarounds. That’s why it has been constantly evolving throughout the years. In the case of our
software we use AES while adding the possibility of enabling salting, a process that makes it harder to
guess the password. Although the salting process is implemented in the code, it could only be used in
reality if we had a server to store the passwords in. Consequently, the future encryption process, and
therefore the security of the QR codes, could be easily improved by adding more and more layers of
security. However, while the passwords are not stored anywhere at the moment, the only way to decrypt
the above QR code is with access to the password or many years of random trials.
Decoding and Decryption Process
This part of the process consists of repeating the previous steps backwards to obtain back the
original
message. As long as the password is available this process is not complicated since the computer
handles
all the computation and requires the “password” and the line of encrypted characters as shown in the
interface of the script below:
However, to avoid having to type or copy paste these long strings of text we decided to implement
the decryption mechanisms straight into a QR code scanner, to obtain the results shown below as
output by the scanner:
A screenshot from our scanner decrypting the QR code automatically during scanning
Therefore, somebody trying to read this QR code would get a seemingly meaningless message.
However, while using our software, it is possible to actually read the message after inserting the
right password. This makes it extremely easy to use.
Reading the biological QR code
When checking for the readability of our QR codes using existing software libraries we noticed
that the contrast of the bacteria to the background wasn’t allowing the code to be read. This is
due to QR codes being designed to be of a “darker” colour than their background, hence requiring
more contrast. Therefore, to counteract this we decided to include a QR code reader in the
software that alters the image colors to optimize the readability of our codes. Following is an
example of the task the computer carries automatically, and if you try to scan this with your
phone, you will notice that indeed the unaltered image is not able to be read, while with some
distance adjustments the image on the right will be detected by the phone. However, We would
want to note that the image filtering done by the computer could be improved drastically to
accommodate for artifacts created by glare from the petri dish, and addition of better color
filtering methods, as bacteria strains tend to vary in color.
Figure 7 – edited image from Biological QR code using our software to make it
scannable
Preparing QR code to imprint plate
During our project we found two possible ways of imprinting the shape of a QR code in agar.
These methods resulted in the creation of two automated software processes to reduce the
time and effort it would take to send a biological QR code. This section will show these two
methods:
3D Stamp
In attempts to make a defined enough image of a QR code on a plate we thought of using the
classic method of stamping. To this purpose we needed a stamp in the shape of a QR code.
However, carving it out is not an option as we needed automation to keep the possibility
of using such a communicating method realistic. Therefore, we resorted to the use of a 3D
printer, which brings another challenge to tackle: extruding a 2D image into a 3D file.
Initially we did so by creating a 3D file in CAD software, but not happy with the
scalability of the method we finally decided to develop a python script that would do so
automatically in a matter of seconds. The results of this method can be seen in the
following pictures.
Using these files it is possible to get a 3D printer to create the 3D model in under 2
hours to then proceed to do the stamping.
Gcode for bioprinter
The second method to bring the QR code into physical form is through the bioprinter
we developed, which you can learn more about on our “hardware” page. This method
involves the translation of a QR code image into code that the bioprinter will
interpret as “spatial” operations to move the extruding tip to the desired
locations.
The goal of this code was to be able to translate any QR code into gcode,
therefore we developed a completely custom software capable of doing so. Gcode is
the standard mode of controlling CNC machines, 3D printers and similar tools,
however it is not a programming language that allows for functions and other
operators to calculate variables, instead, it operates with strict commands that
cannot be altered as the machine runs. Therefore, in order to write variable Gcode
that adapts to any kind of QR code we developed a python script that takes any
picture of a QR code and immediately outputs a Gcode file for the bioprinter.
Try out our code!
We have actually uploaded all our code into github for anybody to check out or
try! It’s as easy as running one python script! Feel free to use it:
Github repository
Running the main script will prompt the user to input the desired password to
encrypt and give the following possibilities:
Extra Software (IGEM Project Search Engine)
Among all the code we have created for our IGEM project we also thought
about developing another tool for IGEM as we observed how difficult it was
to really find other teams and what previous teams had worked on. This lead
us to fetch all possible data from all IGEM teams dating back to 2008 and
organize it to create “IGEMdb”, an easy to use tool that allows anybody to
look up past IGEM projects based on filters like: abstract, project title,
project track, team awards and more. We hope that this tool will help future
igem teams brainstorm new possible projects, and maybe even let the IGEM
organization be recognized for all the work that has been developed under it
for more than 10 years.
