So, I want to start using pass, but I need a GPG key for this. This application will store all of my passwords, which means it's very important that I don't lose my private key, once generated.
Hard disks break, cloud providers are generally not trusted. Not that I don't trust them to not mess with my key, but their security can be compromised, and all my passwords could be found.
So, where can I safely store my GPG private key?
I like to store mine on paper.
Using a JavaScript (read: offline) QR code generator, I create an image of my private key in ASCII armoured form, then print this off. Note alongside it the key ID and store it in a physically secure location.
Here's some that should work for you no matter what operating system you use, as long as you have a browser that supports JavaScript.
For Windows users:
Click here to download the JavaScript QR code generator: https://github.com/davidshimjs/qrcodejs/archive/04f46c6a0708418cb7b96fc563eacae0fbf77674.zip
Extract the files somewhere, then proceed edit index.html per the instructions below.
For MacOS or Unix users:
$ # This specific version is to avoid the risk that if someone hijacks `davidshimjs`'s
$ # repository (or he goes rogue), you will still be using the version that I vetted.
$ # For the truly paranoid you don't trust GitHub either, and you will want to verify the code you download yourself.
$ wget https://github.com/davidshimjs/qrcodejs/archive/04f46c6a0708418cb7b96fc563eacae0fbf77674.zip
$ unzip qrcodejs-04f46c6a0708418cb7b96fc563eacae0fbf77674.zip
$ cd qrcodejs-04f46c6a0708418cb7b96fc563eacae0fbf77674/
$ # We need to edit index.html so that it supports pasting your PGP key
$ # Open the file in a text editor like Notepad, vi, or nano
$ vi index.html
Change line 11 from:
<input id="text" type="text" value="http://jindo.dev.naver.com/collie" style="width:80%" /><br />
to:
<textarea id="text" type="text" value="http://jindo.dev.naver.com/collie" style="width:80%" /></textarea><br />
Now navigate to the directory you get here with Explorer, Finder, or Nautilus, etc.
For example:
$ pwd
/Users/george/Documents/Code/qrcodejs/qrcodejs-04f46c6a0708418cb7b96fc563eacae0fbf77674
$ open .
Now, double click on the index.html file you just edited and saved.
You will most likely need to break up your PGP key into quarters or even smaller to create nice big QR codes that you can easily scan later. After pasting in the text area, click away from the text box and your QR code should appear. Save each one as you go and name them appropriately so that you know their order!
After you've created all the codes, scan them with, for example, a mobile phone QR code scanner app. For the paranoid, keep this device offline once you've installed a barcode reader and then perform a full wipe and factory reset of the device before putting it back online. This will prevent the QR scanner app from leaking your PGP key.
If you have a large key or lots of keys I recommend paperbak, although be sure to write down instructions on how to recover the data later. Just as important as how you back it up is how you restore it from a backup. I'd probably try this with dummy data just to be sure you know exactly how it works.
Worth noting you can protect your private key with a passphrase, so even if it's hosted with a cloud provider they can't see your private key, but then all your password security is reduced to that passphrase rather than the full private key, not to mention cloud providers can disappear overnight.
On the days when my paranoia is like a ripe tomato, begging me to pick it, I split the private key (naturally it is already passphrase-protected) in half, then make a 3rd string by XOR-ing them together. Then I use simple password encryption (gpg --symmetric) on each string, and put each on a remote server on a different continent. Ideally, each remote server is with a different ISP or cloud provider.
But as the medicine was working -- at least until I realized how ambitious the NSA has been -- what I've actually done in the past is merely encrypted the (whole) private key (again using gpg --symmetric) and put it on my smartphone.
Now, having read the other answers, I'm finding the idea of three QR codes, embedded into three family photos, blindingly attractive. Time for stronger medicine?
This is not what I currently use, but I am thinking about it:
This way, I can lose access to a couple shares and still able to access the key; while an attacker would have to compromise 5 different individually secure places where it is easy for me to access but hard for evil dark lord's henchmen in that black car in front of the house <puts on tinfoil>.
One option is to encrypt your key using a passphrase, and store the encrypted key on a cloud service.
I have the key on my laptop (hardware encrypted drive) and on a Truecrypt container on an external hard drive as backup. Ok, it's not zero risk of data loss, but it's down to a level that is acceptable to me.
You can keep your private key in a flash drive and keep this drive in a locker. Also, ensure that you don't use this flash drive for activities which might cause infecting it with some malware.
I keep the key (and other sensitive data like a username / password list) encrypted in a truecrypt container. This container is protected by a massive passphrase. The container is also backed up on cloud storage so edits by any of my computers will be sync'd.
It's not perfect, but if the cloud provider dies, I still have it sync'd on my computers. If the file itself is compromised, they'd have to crack the truecyrpt phrase and the key passphrase.
I would use steganography to place the encrypted key in a series of 100 photos that I upload on several cloud storage (box, dropbox and ovh) for example.
So first you need to know there is something on those picture, find out what and decrypt it.
It's a bit extreme but it resist fire better than paper.
I have two keys, one less secure stored on the computer and another one in an OpenPGP Card. The latter is as safe as it possibly gets because the private key never leaves the chip on the card. (Though, years ago, for best security I had to slightly modify gpg to use my card reader's secure keypad instead of getting the card's PIN from the PC's keyboard which may be prone to keylogger attacks.)
I store mine inside a KeePassX encrypted file, this file is saved inside a git repository which I clone on all machines I need to use the passwords. The added benefit is that I can keep passwords synchronized while if the server for some reason destroys the file I can always use any of the cloned repositories. If I am paranoid I can put a truecrypt volume containing the KeePassX encrypted file.
Git also gives me versioning so I can always get back to previous versions of my passwords file, that's preatty neet.
I really like the idea of having a very-long-term last-resort backup on paper. (Alongside an encrypted archival CD in a secure location.) I just can't find a QR generator that supports the full length of a private key, and I don't trust paperbak until they fix the AES key generation (plus it appears to be Windows-only).
I did find optar which will encode any length of data into a machine-readable format, but for now you have to compile it from C manually. [Shouldn't be hard to put something in Homebrew for Mac people, and perhaps a samaritan can maintain a Windows build, if it proves to work well.]
paperkey should be good for printing off / using OCR to restore a private key, and creating minimal characters for a barcode / QR code generator.
Do the following:
R and C.R and column C and memorize the character X you find there.The key stored there is useless without R, C and X (given that you know the trick, of course). If one can afford the time to find R, C and X, well... good luck now guessing my password.
Also memorizing R, C and X should be very easy from the perspective of the one introducing the change.
Hint: don't do it at the very beginning or end of the string. There are patterns to be followed there, it would be very easy to guess the change.
The private key is already encrypted. Encrypting it symmetrically once more wouldn't hurt though. After that the worry should be about physical security. Media durability and safety off site should be the main considerations. A usb key is probably ok for at least ten years as long as usb ports are available. Put the key in a safe place. A Safety deposit box or good safe off site are good possibilities. This should allow for a recovery in the event that the system you are using now breaks in some unrecoverable way. label and date the usb stick. An encrypted copy of the key's revocation certificate should also be stored with it. make a couple of duplicates if you are worried about usb stick failure.
disclaimer: pointing you to a piece of code I am writing / my own 'small' solution
For solving this kind of problems (and more generally 'archiving' important, moderate-size stuff on paper) I am working on qrdump, a way to automatically
Of course the inverse transformation is also implemented.
For example:
bash-4.4$ FOLDER_TESTS=$(mktemp -d)
bash-4.4$ cd $FOLDER_TESTS/
bash-4.4$ head -c 4096 </dev/urandom > dummy.dat # create a random file, 4096 bytes
bash-4.4$ sha256sum dummy.dat
02f2c6dd472f43e9187043271257c1bf87a2f43b771d843e45b201892d9e7b84 dummy.dat
bash-4.4$ bash ~/Desktop/Git/qrdump/src/qrdump.sh --create-A4 --base64 --safe-mode --output ./pdf_dump.pdf --input dummy.dat # crete a printable qr-codes pdf of the file
SAFE to use: success restoring check
bash-4.4$ rm dummy.dat # the file is removed, so from now on only way to get it back is to restore from the pdf
bash-4.4$ bash ~/Desktop/Git/qrdump/src/qrdump.sh --base64 --read-A4 --input pdf_dump.pdf --output ./ # restore
bash-4.4$ sha256sum dummy.dat # the digest should be the same as the initial one to confirm good restore
02f2c6dd472f43e9187043271257c1bf87a2f43b771d843e45b201892d9e7b84 dummy.dat
If you are interested, more here:
