3 ms·
I can think of several ways to "take a password encrypted file and split it up in such a way that you can re-assemble it without all of its parts" but being abl
by mdip 3y ago
I can think of several ways to "take a password encrypted file and split it up in such a way that you can re-assemble it without all of its parts" but being able to do so without a password is where it's piqued my interest.
This is one of those things that looks interesting to me as someone who enjoys security topics, algorithms and the like. I can see digging into the source code/reading about the techniques involved because I want to know how it was done. But I am struggling to figure out where something like this would be useful -- is there a threat model where this would be useful as a "layer in the onion" of things protecting sensitive data or a way in which this would be superior for a use case that isn't already solved better by something else?
Even the author kind of jokes about an old diary password vs remembering enough hiding places. I think the latter would be a much bigger problem from personal experience and would require having fewer parts and more hiding places, eroding the provided security in the process[0]. :)
Multi-sig comes to mind, but my only exposure to that is "having to participate in it" by "putting a USB key in and running a program along with two of my coworkers" in order to push the one update we ever pushed with that tooling. I remember we all had to provide our keys and "if I was out sick, no update was going out" but I'm not sure if that was a limitation of what we were using or if we just set them up that way because it was "alpha" at the time.
None-the-less, very interesting!
[0] I can imagine, though, that "under the mattress" would be the equivalent security to setting your password to "password".
- hmottestad 3y agoWhat about using it to share information with people for them to use in an emergency. Data is stored in multiple locations, but only someone with access to 3 of them would be able to read the data. The existing physical access controls would be the actual safety mechanism. A thief would have to break into 3 locations in order to get the data. We could just encrypt the data and then split the password into three pieces and store those in different locations, but then you would have to store both the data and the password.
- mjevans 3y agoStep 1 : Create a compressed (must not 'store') archive split into small-ish sections of size N/K. Step 2 : Run par2 against the archive sections and create as much parity as possible. Step 3 : Distribute any middle (not the start of the archive, and not the incomplete end piece) segments of the archive and a 'correct' number of parity / recovery packets. If a complete count of the archive and parity pieces are brought together, par2 can recover the remaining pieces of the archive and extraction will be possible. The hashes only (no recovery data) par2 file should be distributed with all copies.
- hgomersall 3y agoThis is what Shamir's secret sharing algorithm does, just that that has the benefit of being information-theoretically secure.
- crazygringo 3y agoExcept that there are problems with the emergency scenario on both sides: - In an actual urgent emergency, getting in touch with the 3 people and getting the data might be difficult and take days/weeks. One is on vacation, another is going to take a couple of days to try to remember where they stored the USB key... - And nothing limits it to emergencies. The 3 people can just get together immediately and examine the valuable information inside, whether it's account numbers, crypto keys, a will, etc. So the only value here is in not having to remember a separate password. But I expect it's just as likely for people to lose the files entirely as much as it is for them to lose passwords. If you share a password-encrypted file with 5 friends, I wouldn't be surprised if 10 years later, only 1 of them still had it. In that case, better to store file+password per-person, rather than require 3 of them to keep it.
- UncleMeat 3y agoWorse than that. "Oh fuck, I lost that thing" is going to be a common occurrence in these scenarios. Data lost forever. You can then go to K-of-N schemes or whatever, but the truth is that if you don't have a professional obligation to keep some data safe and accessible, people will simply lose it (and this will still happen in plenty of cases where you do have a professional obligation).
- deleted 3y ago[deleted]