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A proposal for pseudonymous, peer-to-peer lending on OpenBazaar using Ricardian contracts and distributed collateralized trusts (dCT)

Peer-to-Peer Lending on OpenBazaar

0

Preamble

Banks are centralised institutions that, among other things, offer credit to individuals, groups and corporations. Historically, banks were a nexus of borrowers and lenders, matching the supply of liquidity to the demand for credit. The primary role of a bank was risk management in the form of the due diligence required to assess if a potential borrower was a worthwhile investment. With the advent of nation-state money printing and fractional-reserve banking, whereby money is lent into existence and losses are publicly subsidized by inflation and bailouts, the traditional care of risk management for loans has all but been obiliterated.

Peer-to-peer (P2P) lending has emerged as a means to decentralise the oligopolistic hold that banks possess in every category for lending. While P2P lending is still in early days, regulatory pressure is mounting making P2P lending services using fiat dollars especially vulnerable to the legacy financial/political order. Using Bitcoin, this legacy threat is largely eliminated, but introduces new problems in the traditional approach of risk management. The purpose of this article is to suggest possible solutions to these problems and how they might be executed on a pseudonymous censorship-resistant marketplace like OpenBazaar.

Ricardian Loan Contracts

As with other goods and services on OpenBazaar, the loan is drawn up as a Ricardian-style contract that I will refer to as the loan contract for the rest of the article. The loan contract is initially written by the borrower and distributed/published on the OpenBazaar network, as the borrower is trying to convince the market to purchase their unmaterialized future good (a interest markup of the original loan amount).

Let us imagine a borrower, Bob, and a creditor, Alice:

Step 1: Bob creates a loan contract

The loan contract specifies that Bob wishes to exchange 110 mBTC in 1 year for 100 mBTC now. The interest rate is 10% p.a. The following fields are introduced in the loan contract:

1. Loan_amount: 100 mBTC
2. Loan_term: 1 year   
3. Interest_rate: 10% p.a.
4. Repayment schedule: 10 mBTC by the end of each month

Bob digitally signs the contract and publishes it to the network.

Example Loan Contract

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

<?xml version="1.0"?>

<!-- Borrower NYM -->
	<nym_id> BOB-NYM-ID-HASH </nym_id>

<!-- Node_ID -->
	<node_ID> XXX-YYY-123 </node_ID>

<!-- Loan -->
	<btc_addr> 03d728ad6757d4784effea04d47baafa216cf474866c2d4dc99b1e8e3eb936e730 </btc_addr>
	<loan_amt> 100 mBTC </loan_amt>
	<loan_term> 12 months </loan_term>	
	<interest_pa> 10% </interest_pa>
	<repayment_sched> 10 mBTC/month </repayment_sched>
	
<!-- Borrower PGP Key -->
<PGP_Public_Key>
- -----BEGIN PGP PUBLIC KEY BLOCK-----
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Comment: Email security by Mailvelope - http://www.mailvelope.com

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- -----END PGP PUBLIC KEY BLOCK-----
</PGP_Public_Key>
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The resulting filename is labelled according to the SHA1 hash of the document: 6127dbed6e218567de94dbd26e7c5fa350de3b9c

Step 2: Alice accepts the loan contract

Alice agrees with the contract and appends the following data:

  1. A schedule of repayment bitcoin addresses (i.e. an address for January, February etc)
  • There are an estimated 12 repayment schedules in the example, so Alice attached 12 unique addresses for Bob to send each repayment
  1. A bitcoin address for the funds to be lent (with a signed message from that address for verification purposes)

If Alice wants to change the terms of part of the contract, she can write, sign and send a fresh contract to Bob. If Bob disagrees, he can simply ignore the contract, or sign it if the change in terms acceptable (e.g. Alice increases the interest rate to 11% p.a., or changes the schedule to fortnightly repayments). Note that this is the only stage where this can happen as once both parties have signed the terms of the contract, it is locked-in as far as the arbiter is concerned for dispute resolution purposes.

Example of an Accepted Loan Contract

<?xml version="1.0"?>

<-- Loan Contract -->
	<Loan_offer_hash> 6127dbed6e218567de94dbd26e7c5fa350de3b9c </Loan_offer_hash>

<!-- Lender NYM -->
	<nym_id> ALICE-NYM-ID-HASH </nym_id>

<!-- Node_ID -->
	<node_ID> AAA-BBB-123 </node_ID>

<!-- Loan Repayment Addresses -->
	<repayment_addr> 1Hmv2gUMqypH5FENoJ1bXkFbWJHXpYv4mr </repayment_addr>
	<repayment_addr> 1M8Jyac6j8PAN8P2s7SL64PDpTXGuQhVs4 </repayment_addr>
	<repayment_addr> 19eUSSLSjvqYK4XN7VC3SEKYhqDaXWGW9y </repayment_addr>
	<repayment_addr> 19eUSSLSjvqYK4XN7VC3SEKYhqDaXWGW9y </repayment_addr>
	<repayment_addr> 1LBggLaYNA2pXViT3xLSRcvBp2GGMaVZrp </repayment_addr>
	<repayment_addr> 1NoErV3DqskowS5ehb2t2Ru4DsQPSS4ePm </repayment_addr>
	<repayment_addr> 179zt3Tt2QNxDZcwQ8cxNNpF7PXDGouoCJ </repayment_addr>
	<repayment_addr> 1MHhhoahdAanHJx3JXxGTMqe2s5XKxgToS </repayment_addr>
	<repayment_addr> 1DyupVxmFcLW3MPTrZ8tyUEQXNFqgNAuXf </repayment_addr>
	<repayment_addr> 1DYNcXAe7nQR5YPKhFbrz1QWEfnJQJd5zR </repayment_addr>
	
<!-- Loan Funding Verification -->
	<addr_message_sig>
-----BEGIN-SIGNATURE-BLOCK-------------------------------------
Address:    1Cpbd5tKaDiXuChctbePpYjUz1PvRzVUiq
Message:    "I control the bitcoin in this address"
PublicKey:  04b728f56bdc4aa8eb213a08ac0a3a95f8eaf4150a988d8754
            e6973e5701418422d89373eb1f2c1125315eeddb7d7557902e
            5521a900a2b71e233441a2d333e304
Signature:  f51cd1645a779c5b2db27405e21a6347a6baec3d26b1e78701
            3c9a824b9ff4e94504c3ff07a116079064ff6f7bd5a508673d
            92be1835f6f47ea824f2b960f90c
-----END-SIGNATURE-BLOCK---------------------------------------
	</addr_message_sig>
	
<!-- Lender PGP Key -->
	<PGP_Public_Key>
-----BEGIN PGP PUBLIC KEY BLOCK-----
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	</PGP_Public_Key>
-----BEGIN PGP SIGNATURE-----
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Step 3: Bob accepts Alice's offer and sends to the contract to the arbiter

Bob verifies that Alice has the funds and digitally signs the contract. Bob sends the contract to Alice (signifying agreement) and to the arbiter.

Step 4: Funds are transferred; repayment-receipt tracking begins (last signed receipt)

Upon receiving the signed contract from Bob, Alice transfers 100 mBTC to Bob's nominated bitcoin address. To keep track of repayments and the balance of the loan, Alice appends the balance of the loan to the contract, digitally signs it, and sends it to Bob and the arbiter.

For every repayment, Alice adjusts the balance of the outstanding loan. The contract is digitally signed sent to the borrower and arbiter. If the lender fails to issue receipts for repayments, the borrower can issue a repayment receipt to lender and arbiter with the new balance. Irrespective of who issues repayment receipts, the entire process and balance is auditable by the arbiter via the blockchain and the 'last signed receipts'.

This process can continue until the loan has been paid in full and the outstanding balance is zero.

Risk Management

Part 1: Credit Ratings and Collateral

The process above has thus far described how the loan contract is created and processed for auditing purposes by the arbiter. However, it has not dealt with how loan contracts will be protected from fraud by bad actors on OpenBazaar. Traditionally, there are two major ways to manage risk for potential loans:

  1. Assess the borrower's credit rating
  2. Require collateral for the loan
Credit Rating

an estimate of the ability of a person or organization to fulfill their financial commitments, based on previous dealings.

As a credit rating often involves an individual disclosing their income and previous financial dealings to the creditor and other third parties, the concept of a traditional credit rating is incompatible with the goals and purpose of OpenBazaar. New and innovative solutions are required assess the credit-worthiness of an individual in a pseudonymous marketplace.

Collateral

something pledged as security for repayment of a loan, to be forfeited in the event of a default.

A borrower must provide collateral to the creditor before a loan is approved. Collateral can be any good belonging to the borrower that has an equivalent value to the amount being loaned. In case of a credit default, the creditor can physically possess the collateral to recover their losses.

Part 2: Web of Trust

In OpenBazaar, reputation management of your pseudonym (nym) is managed in a number of ways. Firstly, the pseudonym can have a value ascribed to it via a proof of burn. Effectively, this serves two purposes:

  1. Inhibits Sybil attacks by promoting trade with valuable identities
  2. Signals the level of risk associated with trade (e.g. selling a 10 mBTC good with a 1 mBTC nym is less risky than selling it to a 0.01 mBTC nym).

On the second layer, a bitcoin-otc style of web of trust allows peers to rate each other from -10 (Bernie Madoff) to +10 (Satoshi Nakamoto). The cumulative rating on the web of trust is another measure of risk other parties can consider before making a trade with you. Moreover, the network of peers and their corresponding rating also is a measure of the quantity and quality of that rating. Individuals creating 20 sockpuppets can easily be identified as a closed off web by viewing their trust graph, which is a visual representation of their trust relationships. Lastly, web of trust ratings aren't predicated on a trade, allowing existing trust networks to be translated into the system. The web of trust platform can be expanded to further differentiate between free and trade-based ratings to signal more information to other parties.

In the context of peer-to-peer lending, the web of trust can act as a form of credit rating.

Part 3: Web of Credit

Taking the web of trust concept one step further, OpenBazaar can facilitate peers extending lines of credit to each other. If there is a successful trade between Alice and Bob, Alice may choose to extend a 5 mBTC line of credit to Bob. Bob can borrow this money at any time according to the prescribed conditions set by Alice. The funds can be kept in a 2-of-3 multisignature address, using an arbiter as a third signature. This line of credit can be publicly disclosed and audited by other peers. The aggregate of a pseudonym's line of credit becomes a powerful and informative risk signal for other peers, with risk being inversely proportional to the sum total line of credit.

The line of credit can be considered as collateral by a potential creditor, knowing that a pseudonym's line of credit can be called upon to satisfy a renumberation of second loan. For individual extending lines of credit, they have an opportunity to invest in successful and well-regarded trade partners.

Part 4: Collateral as User-Created Assets

In OpenBazaar, collateral can be transferred by digitally signing possession of a user-created asset, represented by a Ricardian contract. Briefly, Jack may posses 0.1 ounces of gold and wants to exchange it for other goods and services on OpenBazaar. Jack writes a contract stating that he has possession of 0.1 ounces of gold. To sign ownership of that contract to another individual, Jill, Jack can create a fresh contract with the following data:

  1. A encrypted copy of the old contract using Jill's public key
  2. Updated ownership details (i.e. Jill owns 0.1 ounces of gold)

The new contract is then digitally signed with Jack's private key. Now, this entire process assumes that Jack actually has 0.1 ounces of gold behind the contract and is able to physically transfer the goods or their custody (if a third party, like a vault, is holding them). The burden of proof will be on Jack to demonstrate to Jill that contract is valid. Jack can also seek other highly rated (web of trust) third parties or arbiters to sign the initial contract after they are satisfied with Jack's proof.

Outside of the Ricardian contract model in OpenBazaar, user-generated assets from colored coins or other sources (Mastercoin, Counterparty, OpenTransactions etc), can also be offered as collateral for a loan.

Part 5: Collateral and Distributed Collateralized Trusts

What if a user like Bob is unable to provide sufficient collateral for the loan due to either: 1) his wealth status living in a developing country, or 2) providing collateral in the traditional sense would reveal his pseudonym's identity?

One possible solution is for Bob to purchase collateral from a distributed collateralized trust or dCT. A dCT is a collection of users that pool a certain value of funds in essentially a term deposit. This term deposit serves as collateral for a loan in the event that the borrower defaults. In return for this risk, the borrower pays each member of the trust a fee that makes up the effective interest rate of the term deposit. Using the example thus far, Bob purchases 100 mBTC collateral from a 10 member dCT at the price of 10 mBTC. Under this arrangement, each member of the dCT risks 10 mBTC for a term of 1 year for a return of 1 mBTC (or roughly 10% p.a.), paid for in advance by Bob's fee

Alternatively, Alice could forgo Bob's collateral in favor of a 10 mBTC downpayment upfront. However, Alice will not be compensated if there is a default on the loan. This option could be viable if Alice routinely lends funds to Bob and extends to him a sufficient level of trust.

dCTs however, confer a number of advantages:

  1. Overall level of risk is spread
  2. Multiple layers of due diligence
    • Both the creditor and the dCT will need to evaluate the profitability of lending to Bob, decreasing the chances of spurious lending
    • The dCT can also examine the track record of the creditor, Alice, for their success in picking borrowers
    • The purpose of the loan can be interrogated, and if possible, funds can incrementally be released
  3. Promotes liquidity
    • The creditor has, in effect, insurance in lending
    • The level of risk that is an obstacle for the lender is now lower than the level of risk for each member of the dCT, making relatively capital-intensive loans possible

A dCT is not necessarily appropriate for small-medium sized loans, as a borrow can crowd-source the loan as the level of risk is especially low. However, it will be up to the creditor to evaluate their level of risk tolerance and what steps they take to manage that risk.

Summary

The concepts listed in this article are possible approaches of managing the risk of P2P loans on a pseudonymous network. This proposal is meant to serve as a primer for new and more innovative approaches to manage the risk of P2P lending on OpenBazaar.

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