I'm building a self-destructing USB drive (2022)
interruptlabs.ca
interruptlabs.ca
(Also, like any USB device should, but even more here, you have to ensure that the device controller can't be modified by the USB host.)
1. Completely immutable
2. Could not be maliciously altered by the reader
3. Could not masquerade as a keyboard or a mouse
A modern computer is really a distributed system, but not a lot of people frame the discussion that way.
> The embedded microcontroller is typically a heavily modified 8051 or ARM CPU. In modern implementations, the microcontroller will approach 100 MHz performance levels, and also have several hardware accelerators on-die.
I've got some external USB readers/burners that excel for exactly this sort of thing, and just about anything that will run a modern OS will boot from them.
Admittedly this was almost 20 years ago at this point so maybe some things have improved since then but my understanding is that consumer media uses a different, ink-based technology to write data to disk, and that ink can degrade pretty quickly. This is in contrast to commercial optical media in which the data is stamped into the disk in a manner more akin to a vinyl record.
Some forms of writeable disc media don't use dyes and can last for over 100 years. Check out the link.
But, to your point, one of the variables that affect longevity is the quality of the manufacturing. If you're buying the least expensive media you can find, then the lifespan is indeed shorter. For my cheapo CD-Rs, I've found that they last 5-10 years. You can also make them last longer by storing them in better conditions (vertically, not laying flat, in an airtight container in the freezer).
I tend to go with cheap media, so my personal habit is to burn new copies of my storage discs every 5 years.
One variable I'm recently able to validate (wow, 20 years later!) is write speed. Discs written (for archival) at slower speeds still work. Discs I wrote as fast as possible on my way out the door have mostly failed by now.
Verbatim DVD-R UltraLife Gold Archival Grade 95355
Of course you need Reed Solomon across drives (Eg raidz) regardless of media
Wouldn't the laser of a CD/DVD writer be powerful enough to alter the data after the fact? Not to overwrite it with completely arbitrary data, but flipping a few well-chosen bits should in principle be able to create a backdoor that wasn't there before (if it's a live or install disk, for example).
The issue here is that you can't "unburn" a bit that has been burned. Since you burn 0s, not 1s, all you can do is make more bits 0 -- which would then be corrected by the error correction mechanism. You could alter the EC codes, but that would render them useless and eliminate the ability to correct errors, causing the data to be unreadable by a normal drive due to EC failure.
So, in practice, they're pretty safe. The worst thing that an attacker could do is to render the media unusable.
I don't remember if it required the disc to be un-finalized or not. It probably did.
But this is really an edge case
If not, then you "just" have to find the right spots where such a simultaneous alteration of the payload and the EC code is possible, and which also happens to result in a desirable behavior change.
So you'd have to find mutations that are big enough to not be automatically corrected (more than 2 bits, you can't change, say a single 0x30 to 0x31), and also happen have the right signature so they don't flag as erasures, so you can't freely change bytes to just anything. And then you have to also satisfy the outer code that your modified byte after interleaving is correct. And do it all by only bring able to bit-flip in one direction. The only upside is that you can also flip bits in the correction bytes if you need.
Also, if the data you're modifying has any coding or compression (ZIP, Word documents, videos, most images), or there are checksums, you have to not upset that. And if it's encrypted, you won't know what to change in the first place.
So it's theoretically possible, but it would be very tricky and highly unlikely that you could change a useful piece of data unless you were extremely lucky with what the data was, what you wanted it to be, and where it was on the disk.
If you're concerned about people modifying your CD-R: encrypt and SHA-256 the whole thing and you'll be fine. I assume this threat model mostly targets governments, so they should first do both of those things and maybe also stop leaving them on trains.
(Threats to modify data on the drive or the code of its controller; not concerned with threats that fry the device with power.)
I can't really find a conclusive answer.
Maybe someone can put in an epic weekend, to determine technical and market and logistics feasibility for a trustworthy USB flash drive product, in time to apply for the YC W24 extended deadline. From there, maybe Kickstarter to enthusiasts to fund the Mk. I manufacturing run. With Mk. I for experience and credibility, do enterprise marketing&sales, and/or SBIR to develop solution for possible sale to Federal gov't and contractors. :)
Signed firmware to prevent BadUSB-style attacks, price starts at $40 for 16GB, https://www.kanguru.com/products/kanguru-flashtrust-secure-f...
They have other models with signed firmware + FIPS 140 certified encryption + tamper resistance + physical write-protect switch.
They also sell an SSD enclosure with write-protect switch.
The marketing is a little too breathless to assure me that they did anything to actually make the firmware trustworthy: "Digitally Signed, Trusted Secure Firmware (RSA-2048 Bit)".
Signing something doesn't make it secure against exploits.
If you could recommend other commercial flash drives with signed firmware, they could be compared for security vulnerabilities.
Some models have FIPS-certified encryption, so they may have customers who are high-value targets, motivating attacks/testing for security vulnerabilities.
https://eu.mouser.com/datasheet/2/268/MCHP_S_A0001038949_1-2...
Obviously if someone has physical access they could take the unit apart and circumvent this (but then they could flip the switch too)
Here's some exploits against flash controllers: https://www.bunniestudios.com/blog/?page_id=3592
So I believe that it is an actual hardware lock, in addition to the os having the ro/rw status info.
If someone is interested, Kanguru have faster models than the one linked (which I have too), which is a little slow by today's standard.
The switch as-is prevents the file system from becoming corrupt when you don't "safely remove" the device, and that's plenty enough for the average photographer.
Great little tool.
This may backfire for the hacker.
Authority: Give me the drive
Hacker: Ok. (hands drive)
Authority takes with dry hands and tries it. It doesn't work.
Authority gets upset and starts beating the person.
Authority works up a sweat during the beating
Authority tries drive again - it works
Authority concludes that Hacker's drive only works if Hacker is beaten.
Granted it's only 6" long, but hey it's a $5 wrench.
This would do. $.99 over budget though
Part 2 is https://interruptlabs.ca/2022/08/31/I-m-Building-a-Self-Dest... and was discussed a year ago here:
I'm Building a Self-Destructing USB Drive Part 2 - https://news.ycombinator.com/item?id=32900787 - Sept 2022 (51 comments)
Rubberhose FS does protect you from rubberhose cryptanalysis. That is the point.
You can argue, that it over-protects you, which might be just as or even more dangerous, and that is a fair criticism.
But I don't see how you can argue that it "doesn't protect" you.
Then, is there anything that can protect __you__ from rubber hose cryptanalysis in this sense?
If not, what does my parent comment even mean?
If you want your data to be safe from the rubber hose, you need to have inconvenient access requirements. If your laptop can only be unlocked when 5 keys are turned 'simultaneously', and the keys are held by the ambassadors to the UN with security council vetos, that's going to be hard to accomplish for you, and likely difficult for any one else. Any one of the ambassadors could plausibly lose their key, and then the data is gone, etc.
At a minimum, there should be an always-available partition to contain plausibly-deniable files. Just having an empty USB drive is already suspicious, especially in any stressful situation (why would anyone go to the trouble of carrying something empty?)
The decoy partition should report full capacity even tho it may be small (just like the bogus "large" Chinese knock-off drives that report huge available space but are actually only small memory chips that will fail only when you actually try to load it fully).
Should probably also ship them with a wide variety of bogus off-brand labels. If some authorities figure it out, we don't want bulletins to look for one particular marking set to work.
1. It's new.
2. You're going to load data onto it at your destination.
3. You carry it in case you need to copy data.
I often carry an empty messenger-bag; a USB drive is a lot less trouble to carry. In fact you can easily lose one in the corner of a pocket, and carry it inadvertently.
Provided it had never been written, I would regard an empty USB drive as unremarkable, and not grounds for suspicion. But you can't buy a new USB drive with a hidden partition.
Password protect the partition: if you give one password you get boring content, if you give another you get the good stuff.
But also the cost for you would be the time to call law enforcement, for them is the time to verify the validity of a document, so its just nonsense