When Wifi goes down: Transfer files from Air gapped machines using QR codes

by vinnyglennon • 10 years ago

5 4 10 years ago

coreyp_1• 10 years ago

This is a beautiful idea. How much information does the QR code carry, and how much is transfer boilerplate?

leonjza• 10 years ago

Author here. The amount of data per QR depends on the QR size specified. If I remember correctly, its about 10 bytes per code in the default config (QR code size of 30). Transfer boilerplate is a few codes in the start to setup the conversation and a FIN like message at the end.

th0br0• 10 years ago

The maximum storage capacity seems to be 2953 bytes ([1]). Although that's with error correction level L, so you can only read it as long as you have 93% of all codewords.

[1] https://en.wikipedia.org/wiki/QR_code#Storage

padde• 10 years ago

This is cool.

I guess with high density QR codes, a decent display and a good cam you could transfer a megabyte or more in a minute :D If both devices have front facing cameras, such as smartphones, you could even have a real-time back channel (duplex), and the receiving device could signal the sending device that a certain "frame" got lost and needs to be retransmitted.

When Wifi goes down: Transfer files from Air gapped machines using QR codes

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