[kbenson]

> If you really want to be successful in exploiting people through cyber attacks, I guess you will need some kind of system to provide guaranteed contracts, i.e. proof that if a victim pays the ransom, then the other end of the bargain will be held.

You're describing a legal system and the rule of law. I'm not sure there's way to guarantee anything like you describe when there is some illegality in the nature of the process.

Trade only works when you can trust either the parties involved or the system as a whole to uphold their promises (for the system, that's that involved parties that don't uphold their ends will be punished).

[iEchoic]

> You're describing a legal system and the rule of law. I'm not sure there's way to guarantee anything like you describe when there is some illegality in the nature of the process.

Legal systems aren't the only way to give confidence that both ends of a bargain will be held. As one example, some darknet markets have escrow systems for this purpose. It's not too hard to imagine a way to do this with ransomed code. Reputation-based systems also provide incentives for sellers to deliver on their promises.

[kbenson]

> As one example, some darknet markets have escrow systems for this purpose.

Those only function because the darknet functions as the system, and the punishment for not following through is that the party loses access to or prestige in that market. What entity exists that is trusted and has leverage with both the people that are ransoming (criminals) and average citizens (ostensibly law abiding)? Should I trust a darknet broker to not screw me? No. They have no incentive not to, as long as their actual client, the ransomer, doesn't care. For the same reason, the ransomer should not trust any legal entity, because they can not deliver the money and give it back to the victim (since they are the client).

There may exist a way for this to work, but I certainly can't think of one, and what you described doesn't work either. Trust is the integral factor as I see it, and while you can have trust within a criminal community, and within a law-abiding community, I'm not sure how you get that trust to cross that boundary.

[djmobley]

A simple solution is the one you describe. A reputation system for ransomers. Time earned reputation for upholding promises.

[kbenson]

And how do you ensure you are dealing with the same person from one transaction to the next? Any authority that can confirm an anonymous criminal is who they say they are needs to be illegal to keep law enforcement from finding out the identities, and if not they are still participating in a crime.

Again, how do you trust a criminal person or organization? By their nature, they don't follow the same rules.

[Bartweiss]

Wouldn’t a cryptographic sig suffice for this?

You don’t need an authority vouching for you to become a ‘trusted’ criminal. You just need proof of identity, and a reputation established over time. Drug dealers do this all the time, even though they’re criminals. Hell, it’s even how legitimate businesses work - the FBI isn’t going to shut down Bic for selling shoddy pens, so they build a reputation on “we’re Bic and we did right by you last time”.

An example: a malware group sends every target an RSA-signed demand (with public key disclosed on Pastebin or something). The few people who pay up find that they follow through, so they grow a reputation as sincere. They could even kick things off with a round of freebies - “Here’s your data, here’s our sig, we deleted/unlocked/whatever it for free this time to prove ourselves.” I suppose they’d have to publish demands and outcomes since most targets won’t disclose on their own.

There’s likely a flaw in my specifics (probably around disclosing attacks and proving followthrough), but I only put five minutes into it. As long as you can prove identity, you ought to be able to build ‘trust’.

[kbenson]

> Drug dealers do this all the time, even though they’re criminals.

Drug dealers and those buying from them are both committing illegal acts. That changes the dynamic. Neither party can rely on the legal system to enforce misconduct. That allows an entirely criminal system to work. For example, if you don't pay the drug dealer, they'll just hurt you. If the drug dealer doesn't give you the drugs, or gives you crappy/cut drugs, you just won't use them next time. It's important to note that this transactional relationship does not begin with one party accosting the other, as in the ransomware case.

The ransomware scenario is the equivalent of being mugged in an alleyway, but only of your smartphone, and the mugger offering to give your phone back if you go to an ATM and come back with $100. The whole interaction began with an crime perpetrated by one party on the other.

> As long as you can prove identity, you ought to be able to build ‘trust’.

One problem is that the identity, because it is anonymous, it worth fundamentally less for this purpose than any real identity. The ransomer could decide law enforcement is getting too close, and stop responding to all payments, or abandon the system and someone else could take it over. For any identity used just for this scam, the loss of reputation is irrelevant, and if they are using the same identity for multiple scams they are inviting more law enforcement response. There are no future consequences of mention to screwing people over, since the identity can be changed at any time.

The only thing that really protects you in any of these situations are the incentives of the criminals, but those incentives, be they economic or liberty based, are subject to very different constraints than a legally operating entity. The bottom line is that the person or people involved has started the whole relationship by showing they are willing to screw you over. Establishing trust is not impossible (some people will trust), but it's very hard to do, a large percentage of will never actually trust you, and they likely shouldn't, because you don't have the same incentives or punishments they do.

[iEchoic]

> Any authority that can confirm an anonymous criminal is who they say they are needs to be illegal to keep law enforcement from finding out the identities, and if not they are still participating in a crime.

It's not a requirement that the authority be legal. Note that a person's name isn't required to establish authority, pseudonymous reputation provides assurance as well. Darknet markets have reputation systems, and have already figured this out.

> And how do you ensure you are dealing with the same person from one transaction to the next?

The same way we do it with pseudonymous systems now: by having an authoritative identity somewhere that can verify their actions. @shittywatercolour could make a new account on HN, do an AMA, and post on his Twitter that he's doing an AMA with <name> for proof. Banksy can claim work by posting it on his website. In the same way, a reputable seller on any marketplace (such as a darknet marketplace) could do the same thing.

[kbenson]

> Darknet markets have reputation systems, and have already figured this out.

But again, why should I trust a darknet? What makes a group of criminals trustworthy when a single one isn't?

You haven't really addressed the fundamental problem of trust, just kicked it down the road to a new point. Any legitimate entity seeing usage in an effort to authenticate a criminal will likely be seeing subpoenas for access information. If they are resistant to those subpoenas, then they are helping the criminals, and are acting illegally. Both states have severe negatives for one of the parties.

[iEchoic]

> Those only function because the darknet functions as the system

This isn't true, think Yelp. Why couldn't Yelp exist for ransomers?

[kbenson]

Yelp is a very interesting example. It's hard to make the analogy work because there's an asymmetry to the transaction between restaurant owners and restaurant customers (you don't have to be a customer to leave a review).

Even so, Yelp is renowned for extorting restaurant owners for money (whether or not illegal, and officially extortion)[1]. That's in a market where all participants are supposedly acting legally. Why am I to believe that illegal, anonymous entities won't be willing to burn their reputation (which may only exist for this scam) when they decide to stop?

1: https://www.google.com/search?q=q=yelp+extortion

[Xylakant]

Escrow works well with physical goods. How do you return source code that can be copied endlessly. How many copies do you return? How do you prove that one of them is the "original" copy?

Returning digital goods (or more general "knowledge") works either based on trust or through enforcement. The latter is the rule of law.

[iEchoic]

> Escrow works well with physical goods. How do you return source code that can be copied endlessly. How many copies do you return? How do you prove that one of them is the "original" copy?

Just brainstorming, but:

1. Trusted third party creates a service that (a) provides a one-time-use encryption key (b) provides an endpoint to upload an encrypted blob of information along with an email (or a passcode) and a date after which the decrypted content will be made available to that email (or via that passcode), (c) provides a UI that allows a user to pay $x (redeemable via email/passcode) to wipe the encrypted content from their server, if paid before the ransom date.

2. Malware author compromises system, encrypts content using (a), uploads encrypted content with their email/passcode to (b), sends user a link to (c).

3. Malware author provides some evidence that they haven't also uploaded non-encrypted content elsewhere to give confidence that once the user pays, the content will not exist elsewhere. Some ideas: system/network logs, malware analysis that shows that it only uploads to trusted third-party, providing proof in decompiled source that malware only uploads to trusted third-party, and/or a reputation/review system. Note that this doesn't need to be airtight proof, it just needs to give the victim enough confidence that they think it's worth the risk to hand over some money.

Would this work well, in practice? Who knows. But I think it's a proof-of-concept that shows that there are potentially other ways to escrow ransomed content.

[kbenson]

> Malware author provides some evidence that they haven't also uploaded non-encrypted content elsewhere

Any amount of information that could show this would invariably give away the identity of the hacker. Even then, since the information comes from them, it can't be trusted.

> But I think it's a proof-of-concept that shows that there are potentially other ways to escrow ransomed content.

There's a difference between keeping the owner from their own materials and threatening to spread those materials to others. In the first, you at least know whether you get the files back (for the most part, it might be hard to notice small changed/omissions). In the second, not only do you not necessarily know it's been shared, the blackmailer retains the right to spread it in perpetuity (whether it still retains value or not).

[kbenson]

Even with physical goods, what type of agent would hold the trust of both the criminal and law-abiding elements of the deal? A criminal agent cannot be trusted by a law abiding party, and a law-abiding agent cannot be trusted by a criminal party (they can just give everything back to the rightful owner).

[lawik]

I think this sort of thing could be done using Etherium. Allowing exchange in a mechanical way with code that the parties can verify on their own. A programmed agent being quite impartial. Not sure how hard it would be.

Of course, you can never verify that they will not release the code or keep using it maliciously.

[kbenson]

I think ethereal just hides the problem slightly. If it's information, as you say there's nothing preventing future use of it. If it's physical, there needs to be some holder of the item, and we're back at how can both sides trust the escrow agent?

[lawik]

Indeed. Hard to avoid an element of trust.

[proto-n]

How about an ethereum smart contract that gives back your money unless the owner releases the key used to encrypt your files (which may be possible to verify in the contract)

[kbenson]

That would possibly work in the case of locked files, but not in the case in the submission, where it was about the public release of files. There's no way to ensure they blackmailer didn't keep a copy, and won't threaten again or release anyway.

Also, I'm not familiar enough with ethereum to know whether there are downsides to using it, such as it leaving a trail until laundered (like bitcoin).