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Show HN: Qrkey – Offline private key backup on paper

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Re: Show HN: Qrkey – Offline private key backup on paper

#31
post #28

Be careful where you print these. Most full-featured printer/copier/scanner devices found in office environments can store print job data on the HD where service technicians can access it.

I'll use my own printer, and after it dies on me, I will give it the Office Space treatment ;)

Re: Show HN: Qrkey – Offline private key backup on paper

#34
post #28

Be careful where you print these. Most full-featured printer/copier/scanner devices found in office environments can store print job data on the HD where service technicians can access it.

For extra fun, the printer is likely either on the network or has bluetooth. Age-old poorly written embedded computer with network services written in C is the industry standard. It's totally plausible to break in and steal previously-printed data.

Re: Show HN: Qrkey – Offline private key backup on paper

#35

The usage guide shows which command to run to generate a QR code from a file, and outputs a PDF. But then the command for recovering a file from QR codes takes "file.txt" as input. Is that a typo? Shouldn't that input also be a PDF?

It isn't the PDF you started with once you print it.. A QR code scanner in a camera app, etc, will return text such as a URI.

Re: Show HN: Qrkey – Offline private key backup on paper

#36
post #27
post #24

Earlier quoted context omitted.

You're posing a good question but, if you look at things from this perspective, then every time you type the password to decrypt your private key you should worry about the possibility of some software running on your machine reading it and sending it somewhere. While you pose a valid concern, I think most people don't have to worry about this. The reason is that printing private keys isn't a common practice, so I th…

This certainly applies to office printers. Printers that accept new jobs while printing have to store them somewhere. There have been many incidents of finding old documents on disposed printers because it doesn’t occur to anyone to wipe them first. This especially applies to “copiers”, because a copier is just a printer in the same box as a scanner.

But that wasn't an office printer. Yes, printers do have some memory to store what they need to print, but surely I didn't expect a document to linger there for weeks. Anyway, you're right: we may have to look at printers differently.

Re: Show HN: Qrkey – Offline private key backup on paper

#37
post #28

Be careful where you print these. Most full-featured printer/copier/scanner devices found in office environments can store print job data on the HD where service technicians can access it.

There's always paper-age[0] for those who want to add symmetric encryption (via age) to their qr-encoded secrets! ;)

[0]: https://github.com/matiaskorhonen/paper-age

Edit: I now see it was already mentioned.

Re: Show HN: Qrkey – Offline private key backup on paper

#38

I keep meaning to do something like this in combination with Shamir’s secret sharing (which allows you to split a secret into M blocks, of which any N can be combined to recover the key, and M and N are configurable) to distribute a private key among family members in case of my untimely demise so they can more easily access my financial accounts and stuff. Has anyone done that before, and if so, what tools do you pr…

superbacked, now free and open source, does exactly this.

https://superbacked.com/

Re: Show HN: Qrkey – Offline private key backup on paper

#39
post #24
post #15

How safe is printing a private key, considering potential vulnerabilities in the printer software, firmware, and its online connectivity?

You're posing a good question but, if you look at things from this perspective, then every time you type the password to decrypt your private key you should worry about the possibility of some software running on your machine reading it and sending it somewhere. While you pose a valid concern, I think most people don't have to worry about this. The reason is that printing private keys isn't a common practice, so I th…

> every time you type the password to decrypt your private key you should worry about the possibility of some software running on your machine reading it and sending it somewhere.

Yes, I believe you should. On OSes without sandboxing and protections against exfiltration, this is a substantial concern. And you’d be foolish to e.g. keep a bitcoin private key lying around in your home dir. For this same reason, I think the common practice of leaving non-password-protected SSH keys in ~/.ssh is terrible.

Re: Show HN: Qrkey – Offline private key backup on paper

#40

I keep meaning to do something like this in combination with Shamir’s secret sharing (which allows you to split a secret into M blocks, of which any N can be combined to recover the key, and M and N are configurable) to distribute a private key among family members in case of my untimely demise so they can more easily access my financial accounts and stuff. Has anyone done that before, and if so, what tools do you pr…

One use that I've seen reported whas when Naomi Wu / SexyCyborg was taken into custody by Chinese gov't officials, her friends used SSS to gain access to her social media accounts to report the abduction.
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