A decentralized anonymous marketplace

https://mailman.stanford.edu/pipermail/liberationtech/2014-March/013304.html

by cyberviewer • 12 years ago

114 66 12 years ago

mailman.stanford.edu

m0g• 12 years ago

I'm not sure with OP doesn't address SilkRoad use cases on top of the ones he mentions, that are clearly a minority if we consider what is likely to happen.

bertil• 12 years ago

Well, actually, one that he describes ‘journalists sharing secrets’ can be as big as the drug trade, if you read ‘journalist’ as ‘black hat hacker’ and ‘secrets’ as ‘exploits’. Silk Road couldn’t really do that, because of possible meddling from the central host, but without that risk…

boredinballard• 12 years ago

There is a project called BitMarket that runs a market on the bitmessage platform, really neat.

https://github.com/AyrA/BitMarket

https://bitmessage.org/forum/index.php?topic=3549.0

lappa4• 12 years ago

Just a note: This is not decentralized, it is just a centralized marketplace using the decentralized network Bitmessage.

buzzybee• 12 years ago

I want to see fewer markets. Markets create complex work for people.

exo762• 12 years ago

Can you elaborate?

runeks16• 12 years ago

A market is simply two or more people engaging in a transaction. Why would they engage in the transaction if they think it's more work for them?

sadfnjksdf• 12 years ago

Fully decentralized means everyone has their own autonomous device to act as server and client of the transactions and has a usable decentralized (probably mesh) network. P2P over the standard net is NOT fully decentralized.

infruset• 12 years ago

I think they might want to reconsidert using bitmessage for communications, because it has some serious security failures as it stands. At least according to https://bitmessage.org/forum/index.php?topic=1666.0

roeme• 12 years ago

This is interesting; but as a netizen taken part in international transactions outside of ebay/amazon I'm wondering how one can make the whole transaction safe/trusted in the face of complete anonymity for both seller and buyer.

Escrows are mentioned; but I can't shake the feeling that malicious individuals can game the whole system by creating a lot of sockpuppets and pulling up a smokescreen of trust, ultimately ripping somebody off in a high-value transaction, either as a seller or buyer.

It was/is possible on the platforms mentioned above; I don't imagine it more difficult in a anonymous market.

Looking forward to their results and insights to this.

DanielBMarkham2• 12 years ago

This was what the internet was supposed to be all along, correct? A place where data can move freely from point to point without oversight or control from a central authority.

Strange that we seem to have to keep trying to get back to where we started.

celticninja• 12 years ago

this is not about data, this is about the transacting of physical goods over the internet. I am not sure you understand a) what the OP is suggesting or b) what you are saying.

DanielBMarkham2• 12 years ago

Nope, I got it. I conflated "data" and "purchases", mainly because they are both transactional, and the difference between pure data and physical goods is decreasing by the day.

Thanks for pointing out the difference, though. I should have been clearer in my comment.

iamsalman• 12 years ago

My 2 cents: The element of trust is primary for any financial transaction. There's a reason why eBay Amazon et al employ thousands for conflict resolution b/w buyers and sellers. I wouldn't mind going on SilkRoad for acquiring something which I otherwise cannot but for items which are available elsewhere, I don't mind giving up tiny bit of control while transacting on a commercial platform like eBay.

wildgift• 12 years ago

I think the relationship is desirable, which is why some people will pay a higher price to have a relationship with a vendor, with the understanding that if s transaction goes wrong, the vendor won't balk at fixing the problem. There might also be an expectation that one party or other will extend credit for a few days.

In contrast, there are touch-and-go relationships all the time, like at convenience stores. You can't have the exchange without being present for the entire transaction, because neither party trusts the other.

runeks16• 12 years ago

Escrow services would have to be an integral part of the architecture.

The buyer pays the vendor via an, initially, unsigned multisig 2-of-3 transaction, and the goods are sent when the buyer, the vendor and the escrow service each hold a copy. When the buyer receives the items, he signs the transaction and sends it to the vendor, who signs it and it's valid.

If a dispute occurs, the escrow service will have to decide the case, and side with whichever party it finds most credible. A reputation system for escrow services will be as important as one for vendors, as far as I can see, and they need to be compensated for their service, of course.

amac• 12 years ago

I agree with this. I'm thinking about building a decentralized marketplace but without anonymity for this very reason.

hendzen4• 12 years ago

Fun fact: the original Satoshi bitcoin code included a partially completed distributed market system. Check out the file market.cpp in version 0.1.0.

That said, some major challenges (I've done a bit of thinking about this) - First: Sybil attacks on the reputation system. The author alluded to this but the solution given was vaguely specified and somewhat reminiscent of social network driven overlays like Tonika that a) are inherently problematic for anonymity, and b) hard to grow due to aforementioned invite problem. Another problem is maintaining anonymity while making things efficient - the obvious design would be DHT based but this leads to a whole host of weaknesses (see a paper called 'Hashing it Out In Public' for details), and leads to fragility as DHTs are weakened by high rates of churn, which are quite common in real world p2p networks. Have quite a bit more to say on this topic but I'm on mobile at the moment, may write up an essay at some point.

I would encourage the OP to read up on some of Peter Todd's ideas around fidelity bonds for some ideas on the reputation aspect, also have a look at a (centralized) marketplace called NashX for dispute resolution.

EDIT: also check out the bitcoin-otc web of trust.

runeks16• 12 years ago

Fun fact: the original Satoshi bitcoin code included a partially completed distributed market system. Check out the file market.cpp in version 0.1.0.

For the curious; content of market.cpp and market.h: http://pastebin.com/aa82ajub

liamzebedee• 12 years ago

This system was spread out among other files, including a review system and such. The commit where Satoshi has removed it provides a nice overview:

https://github.com/bitcoin/bitcoin/commit/5253d1ab77fab1995e...

amirouche• 12 years ago

The essay your talking about interest me. To be precise, I'm interested in knowing your point of view regarding the viability of a social network which database is stored in DHT.

edit: in my point of view, marketplace is just another social network.

runeks16• 12 years ago

As far as I can see, the essential problem with decentralized anonymous marketplaces is that reviews need to cost money. Plain and simple. Good reviews have great value, so they need to have a non-zero price. A vendor's review history is the indicator by which you assess whether a vendor is trustworthy or not, and a vendor should have to pay to achieve a trustworthy reputation - if good reviews are free, and you can make money from good reviews, they would have little value.

This is the reason spam emails are so frequent: you can make money from something that costs very little. If reviews were near-free, good reviews would be as plentiful as spam emails.

Free reviews means vendors can make sock-puppet accounts, fake a transaction, and leave a five-star review to themselves. With Silk Road, they take x% of the value of each transaction (or if not, that's at least how it should be), so if a vendor seeks to inflate their review score, they will pay a price for it.

In fact, a good overall review score for a vendor - as far as I can tell - is the sum of all the review "values" (1 to five stars) multiplied by the value of the transaction in question. So a vendor with 10 five-star reviews on 10 orders of a value of 1 BTC each, would have the same score as a vendor with a single five-star review on a single transaction with a value of 10 BTC. Both these vendors would have paid the same amount of money to get this, equal, review score.

I've thought a bit about this, and I don't see how this can be solved in a decentralized market, with no middleman to tax transactions, and make sure that vendors can't get free reviews.

hendzen4• 12 years ago

You can use proof-of-sacrifice to give reviews a cost. Look up OP_RETURN in relation to bitcoin.

runeks16• 12 years ago

Without having thought about it further, this might work.

All we would need to do would be to "burn" a certain percentage of the transaction, eg. by sending it to an provably unspendable address (a hash160 of all zeros, for example).

So the transaction from the customer to the vendor, paying for the goods, would be a 2-of-3 multi-signature transaction (of which the customer, the vendor and the escrow agent each hold a copy), with an output (let's call it output1) to the vendor (paying them for the product), and an OP_RETURN output which specifies a review value (for example, 1 to 5). output1 will then have to be redeemed in a new transaction (created by the vendor), and this transaction will include an output that burns x% of the amount redeemed from output1, and an OP_RETURN output that specifies the vendor's public key.

To calculate the aforementioned total review score for a vendor, all you do is check every transaction that contains the vendor's public key in the OP_RETURN output, and take the sum of the review value multiplied by the amount of bitcoins burned for each of these transactions.

danieltillett• 12 years ago

This is true, but how do you charge reviewers for reviewing? What we realy need is a review system that can't be gamed by those being reviewed.

curiousest• 12 years ago

Reviews could be to the marketplace as exchanges are to Bitcoin: intentionally not part of the architecture.

chippy• 12 years ago

Every seller who sells their product is able to review a buyer. It costs them.

Every buyer who buys something from a seller can review them. It's part of the cost of the goods.

Escrow - same deal.

Edits - this does seem too simple. Is it just naive? Perhaps it doesn't exclude circular transactions and gaming it.

garrettgrimsley• 12 years ago

Yes, it is too simple. If a vendor wants to pose as a buyer and post fakes reviews if there is no cost to the transaction itself then there is no cost for the vendor to post a fake review.

In Silk Road the cost of producing fake reviews was the commission cost of the sale.

ap222132• 12 years ago

It doesn't help me to know that an anonymous person had tipped an anonymous vendor. That doesn't add much value.

However, it would be sufficient if I could somehow determine that someone that I knew had tipped the vendor.

Of course, I don't want my friends to see that I had tipped someone, or all of those of whom I have tipped. I just want it to be possible that they can see my tip, within an aggregate poll, only if and when dealing with that vendor.

hendzen4• 12 years ago

Perfect application for a cryptographic one way accumulator.

See section 5.2 of http://www.cs.stevens.edu/~mdemare/pubs/owa.pdf

runeks16• 12 years ago

It's not important for me to know that an anonymous person tipped an anonymous vendor. That doesn't add much value.

Allow me to disagree (with the last sentence). If you can see that a certain vendor has spent a total of, say, 100 BTC on fees, to build up a reputation, then it doesn't make financial sense for that person to try to scam you in a 1 BTC transaction.

chirau• 12 years ago

What about creating some sort of token which allows a user to review a seller? The token itself can only be generated by a successful and verified transaction. One transaction would equal one token which would allow only one review to only that specific seller.

runeks16• 12 years ago

Yeah that makes sense. But I'm not sure the token should only be generated upon a successful transaction. This would make vendors not want to issue the token if something goes wrong.

When the buyer creates the unsigned multisig transaction, he could request the token from the vendor, so the buyer gets a token in exchange for the unsigned transaction. The token could simply be a unique, random number signed with the vendor's public key.

Upon completion of the transaction (multisig transaction is signed by two parties and published to the network), the buyer could publish a special transaction (the "review transaction"), referencing the vendor's ID (his public key), the token, and the review score/value, along with an optional comment.

allworknoplay3• 12 years ago

When has this ever worked in the real world? I mean, in theory parts of it are nice, but conflating it with the spam problem is probably not accurate; merchants will just pay for positive reviews for themselves and negative ones for competitors. I ask honestly: are there examples where this has worked?

I feel like the much better system is to increase the available information about transaction and/or review volumes associated with a particular account -- that makes it much easier to filter out bullshit, and mimics the way fakes are detected on the rest of the internet.

runeks16• 12 years ago

When has this ever worked in the real world? I mean, in theory parts of it are nice, but conflating it with the spam problem is probably not accurate; merchants will just pay for positive reviews for themselves and negative ones for competitors. I ask honestly: are there examples where this has worked?

eBay works this way [1], and I believe this is how Silk Road operated as well, although I'm not sure.

Merchants who pay for positive reviews for themselves and negative reviews for others have greater expenses than merchants who refrain from this, and, consequently, are less competitive.

Imagine a market place with hundreds or thousands of vendors (which is the size an established market place will grow to, if not much larger). Let's say the average total sale volume per merchant is $10k (I think that's a low figure). To nudge all your competitors' total review score 10% in the wrong direction you'd have to buy 1,000 * $10,000 * 10% = $1M USD worth of items from them, and leave all of them a 1 star feedback. Does this sound like an economically viable business approach?

Paying for positive reviews for yourself is cheaper than that, but you're still less competitive than the merchants who actually satisfy clients, and don't have to spend funds to increase their own rating score.

I'm not saying you can't combine this approach with something else, that might very well be the best solution. But I do think the best solution will require paying for reviews, in some way or another.

I feel like the much better system is to increase the available information about transaction and/or review volumes associated with a particular account -- that makes it much easier to filter out bullshit, and mimics the way fakes are detected on the rest of the internet.

I think I would need more details on this approach to understand what you're suggesting. How would you achieve this in a distributed system? And how do you get around the problem of vendors being able to increase their review score for free?

[1] http://pages.ebay.com/help/sell/fees.html#how

logicchains3• 12 years ago

As a market anarchist, I think it's important to point out that the concept of 'reputation' plays a significant role in many justifications of how a market may function without regulation or any other form of state oversight.

Making a market completely anonymous significantly limits the role reputation can play, which leads me to wonder whether some of the standard arguments for the effectiveness of markets don't apply in this case.

pliny• 12 years ago

One of the goals in the OP:

* Allow users to maintain a pseudonymous identity that carries anonymous trust across transactions.

i.e. anonymous as in it's difficult to establish a real world identity for sellers not anonymous as in no persistent identities at all.

Bootstrapping such a marketplace is obviously difficult, since it's never safe to buy from someone without reputation but everybody starts without reputation - it might be possible to demand some proof-of-work-money to establish a marketplace identity, but I'm not sure where the money would go.

logicchains3• 12 years ago

But if the identity is not connected to a real world identity, there is no legal recourse if that identity cheats you. Most who advocate a pure free market still accept the need for a legal system (not necessarily a State-based one), such that for instance people who take your money without delivering the good may be sued.

An anonymous market means that there's no legal recourse if someone cheats you or steals from you.

runeks16• 12 years ago

Bootstrapping such a marketplace is obviously difficult, since it's never safe to buy from someone without reputation but everybody starts without reputation - it might be possible to demand some proof-of-work-money to establish a marketplace identity, but I'm not sure where the money would go.

I think this is a sensible approach. The money (bitcoins) could simply be destroyed in a transaction associating an identity with the "burn". It would act as the equivalent of a fidelity bond, except the funds would not be recoverable. Perhaps it would make sense to only require this for new vendors, since the cost of a single "burn" for a vendor would be small compared to future revenue, but large for a potential customer, who might not know if they will ever use the service again.

dan_bk• 12 years ago

* Are there any similar attempts we can contribute to or borrow ideas from instead of implementing something on our own?

RetroShare could be used as a platform for this, given that it's:

- 100% Decentralized

- Public key encrypted

- Open source

...and accepts plug-ins for new features. See: http://retroshare.sourceforge.net/

rk172• 12 years ago

The advantages of the anonymous marketplace only really apply to people who's work is being suppressed (activists/journalists) or who's work is rightfully being persecuted (criminals). Maybe there's a case to be made that a lot of people do want to know who they're dealing with, besides that the system (algorithm etc.) thinks they're thrust worthy.

Thiz• 12 years ago

In countries like Venezuela, where government is enforcing laws for price control and shops are shutting down everywhere, an anonymous marketplace would be a godsend.

Citizens under totalitarian regimes are the ones who benefit most from crypto currencies, crypto messaging and crypto markets.

rk172• 12 years ago

Yeah, I should have included that example. Just adding that repression on that scale actually merits regime change more than finding a workaround. Although the workaround might be more feasible in most cases. So, it's a good initiative.

mrfusion• 12 years ago

People are mentioning the need for reviews in such a marketplace. I present one possible solution:

Users pay some fee to leave reviews. the more they pay the more the review is weighted.
Buyers can rate the reviews on how helpful they are.
A small transaction fee is collected from every transaction and distributed to reviewers proportionate to how many votes their each of their reviews has gotten.

I imagine this would prevent review spam, and reward people who post good reviews. In fact it could even support a class of professional reviewers making a living off of reviewing sellers and products.

Ygg2• 12 years ago

What stops company making it, to just pay $10000 to heavily bias their own review?

allworknoplay3• 12 years ago

This is incredibly open to abuse by both vendors and their competitors. A rater's "realness" is probably much better judged by other measures of marketplace activity or simply equal weighting than by their willingness to pay to bias the ranking of a particular review. I'd tend to defer to what's worked in other (semi) anonymous markets -- it's pretty easy to tell when someone is real or not based on their activity patterns.

A better policy is probably to keep raw information available and let people parse it in different ways, rather than baking in a risky and probably fragile system we hope will work.

treirich• 12 years ago

When I read this proposal I immediately thought that Namecoin could be an asset, being a decentralized DNS. Maybe use a variant of Namecoin on individual 'store' nodes to resolve them to a single (non-ICANN) TLD that can be spidered and displayed by several aggregators.

http://en.wikipedia.org/wiki/Namecoin

lappa4• 12 years ago

I've written a description for the potential implementation of a decentralized pseudonymous marketplace. I would appreciate any critical analysis of it.

https://github.com/lapp0/Smart-Market

runeks16• 12 years ago

In my humble opinion, after the advent of bitcoin, there is no longer a reason for a client to do proof-of-work. Bitcoin basically outsources proof-of-work to miners, and presents you with a token that represents proof-of-work. As money, bitcoin proves - just as proof-of-work - that you've worked for it, there is no such thing as free money. The price of a unit of proof-of-work varies wildly, depending on what hardware you have. The price of money is the same for everyone, or at least varies much less.

The problem with proof-of-work is that attackers can invest in powerful hardware - as your spec notes - and have an advantage over other nodes. When paying in bitcoin, as a spam prevention mechanism, no one has an advantage over others. Everyone pays the current market price for bitcoins, and even the miners - who generate bitcoins, and so don't pay the market price - can sell their coins at the market price, so it still comes down to "do I want to use these bitcoins to spam this network, or do I want to sell the coins for $575 per piece?".

lappa4• 12 years ago

I agree and don't plan on using PoW other than in the proof of concept. V0.2 should use PoS because proof of burn (as a believe you are suggesting) is bad for the Bitcoin network (large number of unnecessary tx) and expensive (you don't want to pay the tx fee every time you view a listing). PoS doesn't require any tx in the Bitcoin network (ignoring those you used to earn the stake).

Thanks for the comment. Let me know if you have any other concerns.

justinjlynn2• 12 years ago

Hi. I've been working on a system very similar to OPs description for months now -- http://portobello-road.org . Must be an idea who's time has come, eh? Now I know how Newton and Liebniz felt when they discovered they'd simultaneously invented calculus. Aside from a few architectural decisions (hubs and marketplaces instead of DHT for seller data dissemination and indexing) things are much the same. Would love to join forces and do something cool. I've already gotten a whitepaper put together (though very incomplete I've done a lot of the work in getting a build system for LaTeX up and going and a structure in place) and an initial implementation of a downloadable nodewebkit client and some server code. Just starting on documentation of the communications protocol and getting things going, so it's not very far along. Open to all discussions and debate regarding architecture and specifics.

justinjlynn2• 12 years ago

Oh, forgot to directly link the codebase. It's at https://github.com/portobello-road

brickmort• 12 years ago

very cool! I love the name. It sounds like a b-side by Ween or something. Portobello Road.

64598u3wieodsk• 12 years ago

SpeakEasy comes to mind. It was very much in its infancy last time I checked, but the ideas behind it seemed profound. I don’t have access to .onion sites right now, and I don’t have the url either, but maybe someone remembers and can post the link (assuming it's still up).

A decentralized anonymous marketplace

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