notabot

joined 1 year ago
[–] notabot@lemm.ee 7 points 5 months ago

If you're talking about being able to regain access with no local backups (even just a USB key sewn into your clothing) your going to need to think carefully about the implications if someone else gets hold of your phone, or hijacks your number. Anything you can do to recover from the scenario is a way an attacker can gain access. Attempting to secure this via SMS is going to ne woefully insecure.

That being said, there are a couple of approaches you could consider. One option is to put an encrypted backup on an sftp server or similar and remember the login and passwords, another would be to have a trusted party, say a family member or very close friend, hold the emergency codes for access to your authentication account or backup site.

Storing a backup somewhere is a reasonable approach if you are careful about how you secure it and consider if it meets your threat model. The backup doesn't need to contain all your credentials, just enough to regain access to your actual password vault, so it doesn't need to be updated often, unless that access changes. I would suggest either an export from your authentication app, a copy of the emergency codes, or a text file with the relevant details. Encrypt this with gpg symmetric encryption so you don't have to worry about a key file, and use a long, complex, but reconstructable passphrase. By this I mean a passphrase you remember how to derive, rather than trying to remember a high entropy string directly, so something like the second letter of each word of a phrase that means something to you, a series of digits that are relevant to you, maybe the digits from your first friend's address or something similarly pseudo random, then another phrase. The result is long enough to have enough entropy to be secure, and you'll remember how to generate it more readily than remembering the phrase itself. It needs to be strong as once an adversary has a copy of the file they jave as long as they want to decrypt it. Once encrypted, upload it to a reliable storage location that you can access with just a username and password. Now you need to memorize the storage location, username, password and decryption passphrase generator, but you can recover even to a new phone.

The second option is to generate the emergency, or backup, codes to your authentication account, or the storage you sync it to, and have someone you trust keep them, only to be revealed if you contact them and they're sure it's you. To be more secure, split each code into two halves and have each held by a different person.

[–] notabot@lemm.ee 8 points 5 months ago* (last edited 5 months ago) (1 children)

I've found HSBC to be ok using Firefox on Linux. I don't know if they have integrations with any accounting software, but the web access works well, and you can export your transactions for processing locally.

ETA: I've run small business accounting on Gnucash, I found the learning curve a bit steep, but once you 'get it' it's handy.

[–] notabot@lemm.ee 1 points 5 months ago

Sorry for the slow reply, life occurred.

I think I understand where you're coming from with the desired to be productive and not reinstall. I think I've been there too! One thing that I can suggest, if you do have the time, is to learn a system like Ansible and use it to setup and configure your machine. The discipline of keeping all of the config as source rather than making ad-hoc changes reduces the chance of thinking you'll make just one little change and breaking something, and, if something does go wrong, you can get back to your working configuration quickly.

Bearing in mind that there really isn't anything you can do to stop yourself if you're really determined to not lose the data, because if you can read it at any time you can back it up, the closest you are likely to come is something like creating new key with GPG then using the TPM to wrap your secret key and deleting the original. That way the key is only usable on that specific machine. Then use the key-pair to encrypt your 'guard' files. You can still decrypt them because you have the wrapped secret keys and you're on the same machine, but if you wipe the drive and lose those keys the data is gone. The TPM wrapping prevents you from taking the keys to a different machine to decrypt your data.

There's an article with some examples here,

Having said all of that, this still doesn't help if you just clone the disk as all of the data, including the wrapped key and the encrypted files will be cloned. The one difference there is that the serial number of the hard drive will be different. Maybe you could use that, combined with a passphrase as the passphrase for your GPG key, but we're getting into pretty esoteric territory here. So you could generate a secret key with a command like:

( lsblk -dno SERIAL /dev/sdb ; zenity --title "Enter decrypt password" --password) | sha1sum | cut -c1-40

Where /dev/sdb is the device your root partition is on. zenity is a handy utility for displaying dialogs, there are others available. In this use it just prompts for a passsword. We then concatenate the drive serial number from lsblk with the password you entered and hash the result. The hashing is really only a convenient way to mix the two without worrying about the newline lsblk spits out. Don't record the result of this command, but use it to set the passphrase on your new GPG key. Wrapping the secret key in the manner the article above suggests is a nice extra step to make it harder to move the drive to another machine or mess around in that sort of way, but not strictly necessary as that wasn't in the scope of your original question.

Now you can encrypt your file with: gpg -e -r <your key name> <your file>'. That will produce an encrypted version of called.gpg. To decrypt the file you can get gpg` to use the hashing command from above to get the passphrase with something like:

gpg -d --pinentry-mode=loopback --batch --passphrase-fd 3 <your file>.gpg 3< <( ( lsblk -dno SERIAL /dev/sdb ; zenity --title "Enter decrypt password" --password) | sha1sum | cut -c1-40 )

Once you've tested that you can decrypt the file successfully you can remove the original, plaintext, file. Your data is now encrypted with a key that is secured with a passphrase made of a string you know and the serial number of your disk and optionally wrapped with a key from the TPM that is tied to your physical machine. If you change the disk or the machine the data is irretrievable (ignoring the caveats discussed above). I think that's about as close to your original goal as you can get. It's rough around the edges, and I'm not sure I'd trust my data to it, but I believe it'll work. If you do something like this, please test it thoroughly, I can't guarantee it!

[–] notabot@lemm.ee 8 points 5 months ago

I was more suggesting that it might be a bit eldritch, but sometimes humor doesn't come across quite right/

The linked paper is focused on studying the 'perforation-type anchor' they use to hold the tissue to the mold as it grows, rather than keeping it alive afterwards. During growth the tissue and mold were submerged, or partially submerged, in a suitable medium to keep the cells healthy, and it was only when the resulting models were tested that they were removed (although one test did seem to involve letting it dry out to see if the anchors held). Growing the various layers of cells seems to be a solved problem, and I suspect that includes keeping them supplied with nutrients and such, so the authors aren't examining that. What's not solved is how to keep the tissue attached to a robot, which is what the authors were studying.

[–] notabot@lemm.ee 10 points 5 months ago (3 children)

Do you really want to know? There are some things that the human mind is not meant to contemplate.

[–] notabot@lemm.ee 26 points 5 months ago (4 children)

For most people, your brain is probably pretty good at vividly imaging the sensation of licking different surfaces. Try it; focus an imagine licking a towel. Mmm. Fluffy!

[–] notabot@lemm.ee 3 points 5 months ago (2 children)

This seems like a very complicated way to achieve your goal! It sounds like sitting yourself down and giving you a stern talking to might be a beter aporoach.

Having said that, if you have these very important files that you don't want to lose, please make sure they're backed up somewhere off of your machine. Storage fails, and it's a horrible feeling losing something important. Unfortunately doing so would defeat the approach you're thinking of.

This might be a case of needing to reframe the question to get to the cause of the issue, and then solve that. So, why do you want to make it hard to reinstall your machine? Is it the amount of time you spend on it, the chance of screwing it up, needing it working, has it become a compulsion or something else? Maybe if we can get to the root of the issue we can find a solution.

With regard to TPM, it's basically just a key store, so you can use it fir anything really, althought it's normally used by generating a TPM key and using it to encrypt the key that's actually used to encrypt your data, storing the encrypted key with the OS. Just reinstalling won't wipe the TPM, but unless you made an effort to save the encrypted key it'll be gone. Given your problem statement above it just adds to the data you'd need to save, which isn't helpful.

[–] notabot@lemm.ee 2 points 5 months ago (4 children)

Ok, I'm still not clear on exactly what you're trying to achieve as I can't quite see the connection between somehow preventing certain files being duplicated when cloning the disk and preventing yourself from reinstalling the system.

Bear in mind that reinstalling the system would replace all of the OS, so there's no way to leave counter-measures there, and the disk itself can't do anything to your data, even if it could detect a clone operation.

If what you're trying to protect against is someone who knows everything you do accessing your data, you could look to use TPM to store the encryption key for your FDE. That way you don't know the password, it's stored encrypted with a secret key that is, in turn, stored and protected by your CPU. That way a disk clone couldn't be used on any hardware except your specific machine.

[–] notabot@lemm.ee 5 points 5 months ago (6 children)

Nothing can prevent a disk clone cloning the data, and there's no way to make something happen when a disk is cloned as you're not in control of the process.

If you wish to mask the existence of the files, use either full disk encryption, in which case cloning the disk doesn't reveal the existence of the files without the decrypt password, or use a file based encrypted partition such as veracrypt in which case the cloner would just see a single encrypted blob rather than your file names.

Ultimately encrypting the files with gpg means they have already effectively 'destroyed or corrupted' themselves when cloned. If you don't want to reveal the filenames, just call them something else.

If you could be a bit more specific about your threat model people may have better ideas to help.

[–] notabot@lemm.ee 12 points 5 months ago (8 children)

It sounds like you're actually more concerned about the data in the files not being able to 'pop up' elsewhere, rather than the files themselves. In thus case I'd suggest simply encrypting them, probably using gpg. That'll let you set a password that is distinct from the one used for sudo or similar.

You should also be using full disk encryption to reduce the risk of a temporary file being exposed, or even overwritten sectors/pages being available to an attacker.

[–] notabot@lemm.ee 1 points 6 months ago (3 children)

Putting a simple preseed file on a debian install image is probably going to be your best bet. Assuming you can run a VM on your current machine it shouldn't be too difficult to test it until you're happy with it.

[–] notabot@lemm.ee 1 points 6 months ago (5 children)

It's going to be a balance between your time getting an automated approach to work and the cost/effort of getting a monitor. Getting preseed working can be a bit fiddly, but it does mean you've learnt a new skill, getting a monitor sounds like it'll be a pain, and you might only need it once.

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