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For backup purposes, I'd like to print some encrypted secrets as QR codes. I don't have much room for a typical printer. Could a small thermal printer print a

For backup purposes, I'd like to print some encrypted secrets as QR codes. I don't have much room for a typical printer. Could a small thermal printer print a QR code that encodes 500-1000 bytes? If not, anyone know of a decent, durable, low-volume alternative?

dddw 3y ago
Thermal prints fade pretty quickly
user3939382 3y ago
Yes although any thermal printing I've ever done creates a print out that fades over time, so probably a horrible solution for backup codes.
- rodlette 3y ago
  Good point. Thanks!
  - jimnotgym 3y ago
    You can get small inkjets too...
- diggan 3y ago
  Would that happen even if you laminate it + stick it in a dark place?
  - Chingers 3y ago
    The laminating process would probably blacken the entire paper
    - diggan 3y ago
      There are laminators that don't use heat ;)
    - calabin 3y ago
      Yes I found this out the hard way just last week - thought I was being pretty clever with my inside-the-box packing label.
  - szszrk 3y ago
    In my experience yes. Old receipt roles fade even stored in a warehouse. I would try that anyway, as an experiment. A cheap thermal printer for kids is around 10-20 USD (got one for such price with 10 rolls of paper, half of which is sticky paper), has bluetooth, usb and battery. Fits in a pocket. Would be fun to stick such qr code inside some not important book left lying around.
    - Sabinus 3y ago
      I would caution about giving children receipt paper. It may contain a lot of BPA (or replacements). https://www.smh.com.au/business/consumer-affairs/controversial-chemical-removed-from-shop-receipts-over-health-concerns-20221225-p5c8pq.html https://www.smh.com.au/business/consumer-affairs/controversi...
- m_eiman 3y ago
  There are variants that claim to be long-lived, but they're in a tiny minority. Edit: I seem to be misremembering; direct thermal transfer printers aren't available with long life prints, only thermal transfer printers are. https://www.zebra.com/us/en/resource-library/faq/difference-between-direct-thermal-and-thermal-transfer-printing.html https://www.zebra.com/us/en/resource-library/faq/difference-... Which is also thermal printing, but not the kind used here.
alfla 3y ago
a small laser engraver perhaps? looks like you can get one from china close to 100usd
londons_explore 3y ago
1000 bytes is also a huge QR code. Sure, you can do it, but I'd bet that scanning it will be very hard and impossible with some apps where that usecase hasn't been tested.
- Cthulhu_ 3y ago
  I tried to find one, but failed; did find this HN comment: https://news.ycombinator.com/item?id=18498434 https://news.ycombinator.com/item?id=18498434 It says a QR code is specified as being up to 177 pixels wide (and high I presume, because square), where they can have 2 kB of data with medium error correction. It's a bit of a chore, but manageable to do if the data is important enough. Plus, with error correction built in, you can make some mistakes.
donkeyd 3y ago
Others comment that thermal prints don't last long, but that's all dependent on the print material. The typical receipt fades after a couple of months, but Brother has small label printers that are often used in archiving and those labels can last for decades. So just take some time to find the right medium for your needs and thermal printers can be a decent option.
- RobotToaster 3y ago
  One type of brother label printer (the ones that take "tze" cartridges) are thermal transfer printers, which last very well. They transfer pigment from a separate ribbon, rather than chemically change the label.
  - a1o 3y ago
    Do these require a specific software to be able to print or can they take anything and just print? Like, is it a regular driver, could I connect to this brother printer from my iPhone?
    - notatoad 3y ago
      the one i've got (brother p-touch) seems to require a proprietary software suite, but i haven't really put any effort into figuring out whether there's an alternative way to print to it. it definitely does not "just work", it's not detected as a printer in windows.
danielheath 3y ago
If you need to encode 1000 bytes in a durable way, have you considered writing them by hand? Would take me about three-four minutes in each direction.
- rodlette 3y ago
  I considered just writing them, but I was concerned that I'd make a mistake, or be too lazy to do regular test decryptions/restores.
keybpo 3y ago
A small thermal printer would probably be direct thermal, which uses a heat head and heat sensitive coated paper. This fades away naturally, even if kept in the dark. Glue from tape will accelerate it, in case you're thinking about it to protect from abrasion. There's also thermal transfer printers, which use a ribbon as "ink", similar to typewritter. These labels can endure much harder conditions, like scratches, high temperatures and fade. They're used all over the industry. But these aren't usually small printers and have a high cost. At that point I think you have better solutions on printing services (I understand if you don't want to have the files outside of your environment, though.)
Cthulhu_ 3y ago
You could draw it by hand; get some grid paper and a pen or marker, copy the QR code from your screen. There's plenty of error correction in a QR code that you could make some mistakes, I believe.
Fabricio20 3y ago
Funnily enough I'm doing something similar, but QR codes don't quite work out because their density is not enough for me (even after compression..), I've been printing using a laser printer and a software called PaperBack from the OllyDBG guy! It works surprisingly well for backing up data in paper.
ska 3y ago
What about one of those "pocket" photo printers?

dddw 3y ago

Thermal prints fade pretty quickly

user3939382 3y ago

Yes although any thermal printing I've ever done creates a print out that fades over time, so probably a horrible solution for backup codes.

rodlette 3y ago
Good point. Thanks!
- jimnotgym 3y ago
  You can get small inkjets too...
diggan 3y ago
Would that happen even if you laminate it + stick it in a dark place?
- Chingers 3y ago
  The laminating process would probably blacken the entire paper
  - diggan 3y ago
    There are laminators that don't use heat ;)
  - calabin 3y ago
    Yes I found this out the hard way just last week - thought I was being pretty clever with my inside-the-box packing label.
- szszrk 3y ago
  In my experience yes. Old receipt roles fade even stored in a warehouse. I would try that anyway, as an experiment. A cheap thermal printer for kids is around 10-20 USD (got one for such price with 10 rolls of paper, half of which is sticky paper), has bluetooth, usb and battery. Fits in a pocket. Would be fun to stick such qr code inside some not important book left lying around.
  - Sabinus 3y ago
    I would caution about giving children receipt paper. It may contain a lot of BPA (or replacements). https://www.smh.com.au/business/consumer-affairs/controversial-chemical-removed-from-shop-receipts-over-health-concerns-20221225-p5c8pq.html https://www.smh.com.au/business/consumer-affairs/controversi...
m_eiman 3y ago
There are variants that claim to be long-lived, but they're in a tiny minority. Edit: I seem to be misremembering; direct thermal transfer printers aren't available with long life prints, only thermal transfer printers are. https://www.zebra.com/us/en/resource-library/faq/difference-between-direct-thermal-and-thermal-transfer-printing.html https://www.zebra.com/us/en/resource-library/faq/difference-... Which is also thermal printing, but not the kind used here.

alfla 3y ago

a small laser engraver perhaps? looks like you can get one from china close to 100usd

londons_explore 3y ago

1000 bytes is also a huge QR code. Sure, you can do it, but I'd bet that scanning it will be very hard and impossible with some apps where that usecase hasn't been tested.

Cthulhu_ 3y ago
I tried to find one, but failed; did find this HN comment: https://news.ycombinator.com/item?id=18498434 https://news.ycombinator.com/item?id=18498434 It says a QR code is specified as being up to 177 pixels wide (and high I presume, because square), where they can have 2 kB of data with medium error correction. It's a bit of a chore, but manageable to do if the data is important enough. Plus, with error correction built in, you can make some mistakes.

donkeyd 3y ago

Others comment that thermal prints don't last long, but that's all dependent on the print material. The typical receipt fades after a couple of months, but Brother has small label printers that are often used in archiving and those labels can last for decades. So just take some time to find the right medium for your needs and thermal printers can be a decent option.

RobotToaster 3y ago
One type of brother label printer (the ones that take "tze" cartridges) are thermal transfer printers, which last very well. They transfer pigment from a separate ribbon, rather than chemically change the label.
- a1o 3y ago
  Do these require a specific software to be able to print or can they take anything and just print? Like, is it a regular driver, could I connect to this brother printer from my iPhone?
  - notatoad 3y ago
    the one i've got (brother p-touch) seems to require a proprietary software suite, but i haven't really put any effort into figuring out whether there's an alternative way to print to it. it definitely does not "just work", it's not detected as a printer in windows.

danielheath 3y ago

If you need to encode 1000 bytes in a durable way, have you considered writing them by hand? Would take me about three-four minutes in each direction.

rodlette 3y ago
I considered just writing them, but I was concerned that I'd make a mistake, or be too lazy to do regular test decryptions/restores.

keybpo 3y ago

A small thermal printer would probably be direct thermal, which uses a heat head and heat sensitive coated paper. This fades away naturally, even if kept in the dark. Glue from tape will accelerate it, in case you're thinking about it to protect from abrasion. There's also thermal transfer printers, which use a ribbon as "ink", similar to typewritter. These labels can endure much harder conditions, like scratches, high temperatures and fade. They're used all over the industry. But these aren't usually small printers and have a high cost. At that point I think you have better solutions on printing services (I understand if you don't want to have the files outside of your environment, though.)

Cthulhu_ 3y ago

You could draw it by hand; get some grid paper and a pen or marker, copy the QR code from your screen. There's plenty of error correction in a QR code that you could make some mistakes, I believe.

Fabricio20 3y ago

Funnily enough I'm doing something similar, but QR codes don't quite work out because their density is not enough for me (even after compression..), I've been printing using a laser printer and a software called PaperBack from the OllyDBG guy! It works surprisingly well for backing up data in paper.

ska 3y ago

What about one of those "pocket" photo printers?