QR Codes

I came across QR codes recently. QR stands for Quick response. The coded message looks something like this:


In Japan, they are printed on business cards so that you can take a photograph of the code with your mobile phone, and use special software (also in the phone) to decode it. It makes your life simpler so that you dont have to feed the business card information into your phone contact book manually. However they can be used for almost anything – on ads to store contact information etc.

The QR code shown above is my own web business card. It has my name, the names of my websites and my contact email ID. You can go to http://qrcode.kaywa.com/ to generate QR codes, and download an application to read them. Mobile phone applications are also available.

Why they attracted my attention was in connection to digital security: If you digitally sign a document using GPG for example, there is no way to reflect that on a printed version of the document. QR Codes present an easy way: include a QR code for a short summary of the document, digitally signed, into the document itself. To make it watertight, include a URL to the online version of the document, and a hash of the document. Makes sense?

The uses are endless: they can be added to ID cards, where on one side there is human-readable information, and on the other there is QR code, ready to be verified in case of suspected forgery, they can be added to marksheets digitally signed by the university – the list is endless. No softcopy of the marksheet needs to be provided is what makes this schema more interesting.

Here is a signed message from me:


No need to make them black and mundane – in fact you can superimpose your logo. The first reader to unravel the message in this QR Code will get a digitally signed certificate from me! My public key is here. Post in comments.


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