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After the Belfast Project Fiasco, Time For Another Look At Time Capsule Crypto?
JonZittrain (628028) writes "I'm curious whether there are good prospects for 'time capsule encryption,' one of several ways of storing information that renders it inaccessible to anyone until certain conditions — such as the passage of time — are met? Libraries and archives could offer such technology as part of accepting papers and manuscripts, especially in the wake of the 'Belfast Project' situation, where a library promised confidentiality for accounts of the Troubles in North Ireland, and then found itself amidst subpoenas from law enforcement looking to solve long-cold cases. But the principle could apply to any person or company thinking that there's a choice between leaving information exposed to leakage, or destroying it entirely. Some suggested solutions are very much out of the box."
Send it on an elliptical orbit around the sun. Depending how many years you want before the key is back in our neighborhood, you select the appropriate orbit. Hmm, perhaps SpaceX should look into it and start commercializing such a service ;)
Violence is the last refuge of the incompetent. Polar Scope Align for iOS
Most modern cryptography works because it's difficult to solve certain math problems, but the limits of "difficult" keep getting bigger. It should be possible to make a rough estimate of how much processing power will be available to break your encryption by what date, to the parties of interest. Make your keys that strong, and hope you're close.
To build off of the Belfast Project example from TFS, a 50-year timespan might be reasonable. What kind of decryption ability might we have in 50 years? I'm no expert in cryptography, but an elliptic curve algorithm with a fairly-strong key seems reasonable to me. Encrypt it, destroy the plaintext, and forget about it. Forty-five years from now, a government might have the ability to decrypt the material, but they'd have to care, first. It might take sixty years for a data-crunching powerhouse like Google to decrypt it, and perhaps in sixty-five years, they'll see fit to run a PR stunt by unlocking the time capsule.
There's a lot of guesswork and estimation involved, but such is the nature of all time capsules. You're assuming that the capsule will be intact and unlockable at a future time, which necessarily involves predicting future capabilities.
You do not have a moral or legal right to do absolutely anything you want.
Communications with your lawyer are privileged. Give them your information with instructions on when and how to release it. Make sure to pay them in advance.
This is standard stuff in may novels because it kind of works.
Is it 100% effective? Maybe not. But it's a layer of protection. If you are especially paranoid, give one lawyer a 1-time pad encrypted hardcopy file. Give another the key.
The world is made by those who show up for the job.
So who gets to keep the half that goes on the website? What's to stop them from getting subpoenaed, hacked, or otherwise compromised?
Nothing in principle. However, there are secret-sharing techniques that would make this more practical: it is possible to divide a secret into N parts; but construct the divided pieces such that anywhere from 1 to N of them are required to reconstruct the original secret.
This doesn't solve the problem in any fundamental way; but it does help. You can now control both the risk of the secret being permanently lost(increase the number of parties who have parts, possibly even providing a given part to more than one party) and control the risk of enough parties being compromised to reveal the secret(set the number of required parts equal to, or close to N, and distribute the parts among different jurisdictions, storage mechanisms, and so on).
No perfectly elegant solution; but at least you get to pick your poison.
I was thinking about this task a few weeks ago from the point of view of a real-world application: you're travelling in a war zone and want to ensure that your files are safe *even from yourself, your friends, your employer, and everyone who cares about you*. Because if you're taken prisoner, they're not going to use a 30 million dollar supercomputing cluster to crack the encryption on your laptop; they're going to work you over with a pair of pliers, perhaps taking off a few body parts, until you tell them. And if you don't have the key, they'll just threaten harm to you to people you care about who do - assuming they can't outright capture said people as well. Nobody you now can be responsible for the key. The key has to be held by someone who by nature of their contract doesn't give a rat's arse about you and won't change their terms even to save your life.
But of course, what if they were compromised - legally (subpoena), or extrajudicially (someone with a pair of pliers)? So we get into the sitution where a server for a service that controls giving out of keys needs to be safe even from its owners. While terms for key storage involving personal judgement calls (such as "did the person contracting with us successfully make it out of the country and is no longer under coersion?") can't be automated, simple time locks can, so the issue simply comes down to, "Can you keep reliable running key storage system that can't be compromised even by physical access"? A potential solution to reliability (since any system tht locked will be immune to maintenance as well!) would be to store the every key on multiple running systems in different locations in hopes that at least one of them lives long enough to yield the key at the correct time. As for security, for example, even with full memory encryption, ram is vulnerable to cold boot attacks and the key to decrypting memory has to be stored somewhere, but one solution to that is storing critical portions of data only in CPU cache. But that's only one possible attack vector among many. At least you could respond to a subpoena, "Hey, maybe you have a way to get at this data, but I sure don't. If you'd like to fund a multi-million dollar research project on how to get ahold of it, I won't stand in your way, I'll be fully cooperative..." You could also make it harder by having a multi-part key, with each part held by different entities in different jurisdictions. Though that could increase reliability challenges.
In short, at the very least you can make it very, very difficult to get keys. Maybe you can't stop a secret NSA raid on all physical servers taking part the world over, but you could stop pretty much anything else.
Very well; let this abomination unto the Lord begin!
Easier idea. Put the data in a tiny pressurized capsule and drop it deep in the ocean. After a set amount of time the capsule is designed to inflate an air bladder, rise to the surface and transmit via radio frequency.
There's no way to retrieve this ahead of time because:
1. The ocean is vast and the capsule is tiny.
2. The ocean is so deep that you would have to send a robotic submarine to find it and no one would know where to look. If you can lose a plane at the bottom of the ocean, you can lose a 1 foot capsule even more easily.
You guys are thinking too much into this. Any third party you entrust your secret to (bank authorities, lawyers, software etc) is a potential point of breach.
Just keep your information in hard copy (papers, journals etc), put it in a box, lock it up and bury it. Entrust the secret and key to a son/daughter with strict instructions it is not to be opened until you pass away, with the warning that the secrets revealed may destroy the family.
The less people know about it, the more secure it is.
I'd rather trust family who have an interest in protecting your secrets rather than some stranger or worse, impersonal unthinking code. And having a living, thinking secret keeper who can respond to challenges and situations you may not even forsee is far more effective.
A hobbit. They can be trusted. Don't you know nothin'?
No. Then it'd have to be a whole key ring.
-- Alastair