[ANN] METAmarket - Trustless Federated Marketplaces

[agentgreen420]

METAmarket: Trustless Federated Marketplaces
>>> http://metamarket.trade <<<
http://metamarket.trade/whitepaper.html
http://metamarket.trade/contact.html

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ALPHA RELEASE NOW AVAILABLE ON GITHUB!!!
https://github.com/metamarcdw/metamarket/releases

FEATURED ON POPULAR TECHNOLOGY PODCAST "Sovryn Tech"!!!
https://soundcloud.com/sovryntech/svtep0135 (at about 1:24:00)

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Introduction

METAmarket is an open source protocol and proof-of-concept reference client specifying a trustless federated marketplace which uses Bitcoin as a universal currency and Bitmessage as a P2P communication network. Time-locked refund transactions ensure that incentives are aligned toward completing the trade without the need for trusted third parties. Systemic vulnerabilities such as transaction malleability are mitigated through the use of a federated reputation model. This document is a non-technical overview of how the METAmarket client and protocol work. For more technical details, see the protocol specification.

Motivation

Overly centralized marketplaces and payment services extract high fees, impose and abuse excessive control and remove any hope of privacy from users. As more commerce moves online, many consumers may find their lifetime history of purchases (including books, personal items and location details) for sale to advertisers, employers, curious neighbors, stalkers, political opponents and government agencies. An ideal system would be one of secure private transactions directly between buyer and seller without middle men collecting data or adding fees. Such systems are now feasible by combining recently developed technologies for anonymous decentralized payment and messaging systems.

Client

To use the marketplaces, a client application which implements the METAmarket protocol is required. The client is used to post, browse and execute trades. It also requires a Bitcoin Core wallet to handle payments and refunds. A working client is available at:

http://github.com/metamarcdw/metamarket/releases.


How is METAmarket different from other decentralized markets?

    The main difference is how escrow is handled. OpenBazaar uses a trusted-3rd-party escrow system which can be difficult in pseudonymous reputation systems because they are prone to gaming by parties creating negative reviews for competitors. Brawker likewise uses third party escrow but it makes itself the single centralized "trusted" escrow agent and the centralized host for all listings.
    METAmarket instead uses two party escrow directly between buyer and seller with no third party. In our system the buyer and vendor agree to a dispersal ratio beforehand using a time-locked multisig bitcoin refund transaction. This, in addition to the federated reuptation system, ensures both parties have an economic incentive to complete the transaction without the need for a trusted 3rd party.

Who is behind it and how much work has gone into this?

    Originally created by Marc D. Wood over about one year of part time and weekend work, it is now released to the public under the MIT open source license.

What's the history of the project?

    Inspired by Jeremy Spilman's December 2013 blogpost entitled, "The Future of Bitcoin Escrow". I wrote up a rough spec in 2014 for a market based on it that ran over Bitmessage. I then began work on several small bitmessage-oriented side-projects as a means of testing out the Bitmessage API (that would later be used for METAmarket). The first working version (the command line client) was tested in January 2015.

What's the roadmap for METAmarket?

• weight upvotes on fromuser rep?
• auction functionality
• PyQT4 GUI
• 2to3?
• extensive testing
• HD wallet
• integration /w openassets python module for colored coins trade

Can I help?

    Yes! Please connect with us via IRC or GitHub. Testing, working on the code, marketing, and making tutorial and intro videos would be particularly helpful.

[jdebunt]

Looks interesting, browsing through the whitepaper as we speak

[agentgreen420]

Top URL needs fixing.

Thanks, fixed!
Also added some extra content from the FAQ.

[marcus_of_augustus]

Sounds promising ... suggest you also consider PageSigner (tlsnotary) integration https://tlsnotary.org/

[agentgreen420]

Sounds promising ... suggest you also consider PageSigner (tlsnotary) integration https://tlsnotary.org/

Thanks for your feedback!
Could you explain what advantage could be gained by integrating with TLSNotary?

[milo]

What prevents the following scenario:

1. Seller announces item for sale
2. Buyer accepts offer
3. Seller ships item to buyer
4. Buyer receives item, but does not finalize payment to seller.

Thanks.

[agentgreen420]

What prevents the following scenario:

1. Seller announces item for sale
2. Buyer accepts offer
3. Seller ships item to buyer
4. Buyer receives item, but does not finalize payment to seller.

Thanks.

After the locktime, the scamming buyer would likely also broadcast the refund transaction taking a portion of the funds back as well.
In this scenario the vendor will submit bad feedback on the buyer into the market's reputation system, lowering their reputation score significantly.

[milo]

Thanks for the reply.

Why wouldn't the scamming buyer just abandon their bad reputation identity/account and create a new identity/account with an unblemished reputation?  Lather, rinse, repeat.

[TheButterZone]

Make it 2 of 2 multisig so the scamming seller/scamming buyer have mutual assured destruction.

[marcus_of_augustus]

Sounds promising ... suggest you also consider PageSigner (tlsnotary) integration https://tlsnotary.org/

Thanks for your feedback!
Could you explain what advantage could be gained by integrating with TLSNotary?

Decentralised on-line marketplace for bitcoin <-> currency trading.

[cheako]

Thanks for the reply.

Why wouldn't the scamming buyer just abandon their bad reputation identity/account and create a new identity/account with an unblemished reputation?  Lather, rinse, repeat.

Problems like this are simple to solve.  Long computational or network time to create new accounts is one solution.  Proof of tour across currently online users.  Lower reputation if new account is from an address/network that's previously registered users.  Freenet's WoT has an interesting feature where existing users generate CAPTCHA challenges for new users.  It can easily be made non-trivial to create a significant number of bad accounts.

[agentgreen420]

Make it 2 of 2 multisig so the scamming seller/scamming buyer have mutual assured destruction.

METAmarket does in fact use 2of2 multisig escrow.
Please take the time to read the whitepaper before asking questions.
Thanks!

[agentgreen420]

Sounds promising ... suggest you also consider PageSigner (tlsnotary) integration https://tlsnotary.org/

Thanks for your feedback!
Could you explain what advantage could be gained by integrating with TLSNotary?

Decentralised on-line marketplace for bitcoin <-> currency trading.

You can theoretically already use METAmarket to trade anything for bitcoin, including other currencies!
Be it MoneyGram, bank wires, cash in the mail, or even PayPal!
The real innovation that makes this possible is the decentralized two-party multisig escrow, enabled by the federated reputation model.

[agentgreen420]

Thanks for the reply.

Why wouldn't the scamming buyer just abandon their bad reputation identity/account and create a new identity/account with an unblemished reputation?  Lather, rinse, repeat.

Problems like this are simple to solve.  Long computational or network time to create new accounts is one solution.  Proof of tour across currently online users.  Lower reputation if new account is from an address/network that's previously registered users.  Freenet's WoT has an interesting feature where existing users generate CAPTCHA challenges for new users.  It can easily be made non-trivial to create a significant number of bad accounts.

Excellent point cheako, this problem isn't terribly difficult to solve.
In METAmarket, every time you want to register your identity with a marketplace,
you MUST pay a nominal registration fee (in BTC) directly to the Moderator.
This policy not only attaches  monetary cost to mounting a Sybil attack,
but also provides a revenue stream to incentivize the running of the marketplaces themselves.

[TheButterZone]

Make it 2 of 2 multisig so the scamming seller/scamming buyer have mutual assured destruction.

METAmarket does in fact use 2of2 multisig escrow.
Please take the time to read the whitepaper before asking questions.
Thanks!

This "refund transaction" you described nullifies the mutual assured destruction I described. Thanks.

[agentgreen420]

METAmarket does in fact use 2of2 multisig escrow.
Please take the time to read the whitepaper before asking questions.
Thanks!

This "refund transaction" you described nullifies the mutual assured destruction I described. Thanks.

"Mutually assured destruction" is only useful or desirable in the absence of reliable reputation information.
This is not how METAmarket is intended to operate.
If you get around to reading the whitepaper, I always appreciate feedback.

[TheButterZone]

Your whitepaper does not describe how a "nominal" registration fee (easily afforded by scammers) completely eliminates the possibility of Sybil attacks, aka "the absence of reliable reputation information". Are moderators going to make the fee so high and the requirements so stringent that they can afford to fly out and personally run live fingerprints, DNA, retinal scan? And having to trust moderators to kill Sybils is only "trustless" if it means "trust less than 100% but more than 0%".

Or are moderators going to be guarantors for scammers and keep a ledger of who burned how much BTC (which might not even be sufficient to cover all scams), so the scammed sellers can be paid back in part or full, by the moderators in the end?

[agentgreen420]

Your whitepaper does not describe how a "nominal" registration fee (easily afforded by scammers) completely eliminates the possibility of Sybil attacks, aka "the absence of reliable reputation information". Are moderators going to make the fee so high and the requirements so stringent that they can afford to fly out and personally run live fingerprints, DNA, retinal scan? And having to trust moderators to kill Sybils is only "trustless" if it means "trust less than 100% but more than 0%".

You can never 'completely eliminate the possibility' of a Sybil attack on any reputation system .
The whole idea of MAD is that -both- parties have something to lose by being a dishonest trader.
In your scenario, the scamming buyer loses out on some kind of security deposit put in escrow before the trade.
The whole point of the security deposit is to incentivize honest behavior.

This goal is achieved in a different way with METAmarket.

Rather than scammers being incentivized by security deposits,
they're incentivized by the potential to lose their registration fee,
and whatever time/effort/BTC has been burned building their current identity's reputation.

Here's a quote from Jeremy Spilman (also quoted in the white paper):

The first option is to lock up some of Bob’s coins along with Alice’s. That way, Bob can’t simply troll Alice into losing money without losing some of his own. Technically, what we need to do is collect properly sized inputs (account balances) from both Alice and Bob, and then collect all the coins together into a single multisig output.
...
The second option is to setup an automatic release from the escrow where coins are either sent back to Alice, or split some way between Alice and Bob, at some predefined points in the future.

[agentgreen420]

Looks interesting, browsing through the whitepaper as we speak

Many thanks for your interest. Do you have any feedback to add?

[Shindo1988]

Make it 2 of 2 multisig so the scamming seller/scamming buyer have mutual assured destruction.

METAmarket does in fact use 2of2 multisig escrow.
Please take the time to read the whitepaper before asking questions.
Thanks!

multisig does nothing to protect either party, if one party is dishonest.
All it does is just burn coins in case of disagreement.
The problem is, the coins are lost and one party has been f*cked by the other.