Conceptual model for asynchronous physical exchanges

[p.b.]

Hello,

I would like to share a conceptual model exploring the problem of asynchronous physical exchanges between parties who do not know each other and are not present at the same time.
The document proposes a possible architecture aiming to reduce some risks inherent to these exchanges while preserving anonymity, avoiding reliance on trusted intermediaries, and separating monetary settlement from physical state coordination.
The goal of the document is not to present a finished implementation but rather a conceptual framework open to discussion and technical critique.

Documents provided:

• French version (original) – complete document (Epasynchroneorigine)

• English version – Part 1 (TradEpasynchronepb1)

• English version – Part 2 (TradEpasynchronepb2)

https://github.com/pbasynch/asynchronous-physical-exchanges.git

The English version was translated from the French text. If any passage seems unclear in English, the French version may be used as the reference.

Feedback, criticism and technical comments are welcome.

[MarryWithBTC]

I have gone through the github file and read through, I have my concerns about the logistics intervention, but I'll have to go through carefully again.
You uploaded the write up as images and not as texts.

[Ucy]

Sounds like the lock would be internet connected or always online machine/electronic. Seems Futuristic, but i doubt has been invented yet.  A machine that's capable of full inspection or review to verify that a product is according to seller's description would be expensive, large, complex, to also be capable of reviewing almost all product type whether small or big, like from watches to cars. I think this is what humans can handle more effectively, but in much slower pace

So, you would ether combine humans and machines, or humans only for the reviews, and still ensure that the whole process or most of it meets your specifications: asynchronous, anonymous, trustless, no intermediary, decentralized, etc
If you want it so, then there has to be physical system for the whole process, and it possibly should be open to anyone to participate or should be permissionless.

 — Firstly, fund is escrowed by buyer after going through a product and the description of its condition. The product and the condition is sent to collection point with a minimum of two reputable witnesses to review and approve/disapprove it based to the condition. Then the buyer comes to the collection point to inspect it too, if it's according to the stated condition, escrowed bitcoin is released.  *Fund should not be released in cases like this until product condition is finally verified and approved by a minimum of 2 witnesses plus the buyer. One witness could be doing the verification while others approving or disapproving. If product fall short of standard, it's returned.

[p.b.]

MarryWithBTC

Thank you for your feedback and for taking the time to go through the document.

Of course, there is no problem if you would like to review it more carefully before sharing further thoughts, especially regarding the logistical part.
Regarding the PDF files, you are right: they were generated from a format that makes the text difficult to copy or select. I plan to make them available soon in a selectable text format to make reading, quoting, and analysis easier.

Thank you


Ucy

Thank you for your response and for your reflections on the model.

You are correct on one point: in this concept, the physical devices (such as lockers or deposit points) would indeed be permanently connected to the network and interact with the layer B infrastructure.
Regarding the machines capable of inspecting objects, I understand your remark. The idea is not to design a universal machine capable of analyzing every possible type of object (for example cars). In this model, devices could instead be specialized depending on the type or category of objects, using sensors and measurement methods adapted to those specific cases.

I also understand your suggestion of introducing human verification. However, one of the main goals of the model is precisely to limit human intervention in the process as much as possible. Introducing witnesses or human inspections reintroduces trusted third parties and reputation-based mechanisms, which this model specifically attempts to avoid in order to preserve properties such as anonymity, the absence of intermediaries, and decentralization.

You also mention that such a system would require a physical infrastructure open and accessible to participants. On this point I agree: the idea would be for the infrastructure to be usable by different actors, while the layer B registry remains open, distributed, and append-only.
Finally, thank you for proposing an alternative model. I understand the logic behind your approach. However, in this case it introduces several trusted third parties (the witnesses responsible for verifying the object), which is precisely one of the elements this model aims to avoid.

In addition, the fact that the buyer must physically inspect the object before the funds are released introduces certain limitations. In such a scenario, situations of collusion could arise, for example between some witnesses and the buyer, or between the buyer and actors present at the collection point. The buyer could potentially leave with the object or validate its conformity in circumstances that no longer truly guarantee a trustless or intermediary-free process.
Furthermore, in this type of mechanism the release of the escrow ultimately depends on a final action from the buyer. If the buyer never shows up to inspect the object, refuses to validate the transaction, or simply disappears, the escrow can remain locked and the exchange cannot be properly finalized. In the model proposed in this document, this type of blockage is specifically avoided through the introduction of time constraints, automatic conditions, and economic commitments between the actors, which helps reduce direct dependence on human decisions within the process.

Thank you again for your response and for your thought

[Ucy]

Sorry for late reply, p.b
I made my suggestion due to tech constrain in the proposal even though it's a very interesting one I wish has the tech capability. My only issue with the proposal apart from the lock is the commitment by the transporter inform of insurance, for goods lost or stolen in transit.. I think that is a gamble you may hardly find anyone that's willing to take unless for products that aren't worth alots.

Concerning the lock, the humans will still be needed until there is tech that is capable of serving that role effectively.

In the case of trust and reputation, mine is actually not trust based since non of the verification or approval of the witnesses  (even the reputable ones)  are unchecked by other witnesses. If there is any issue ignored by any witness, others would identify it and nothing gets approved unless tolerated by the buyer.
 Collusion will be difficult if there is re-verification by other witnesses. And there will be decentralized arbiters to finally release funds from escrow if buyers do not show up for example, after witness reports

[joniboini]

Maybe you should upload the text directly to GitHub. Personally, I'm not comfortable downloading files from the internet if I don't know the uploader at all. We have had many attacks using PDF files on various devices, too, in the last few months or so. It will be easier for people to read and check their understanding of your project, too. Even if you convert it to txt or something else, some people will still feel uncomfortable.

Your project reminds me of a similar project in the past, although it's geared more toward P2P delivery iirc. I can't remember the name though.

[p.b.]

Thank you for your feedback and for the time you have dedicated to reviewing my project. I also apologize for the delay in my response (Ucy).

Joniboini:
Regarding the comment about the document format, I fully understand the concerns related to downloadable files and the potential risks they may carry. I have therefore taken the time to provide a version that is directly accessible online, without any download required, so that the content can be easily and safely reviewed. The text is now readable and selectable (MarryWithBTC).
https://github.com/pbasynch/asynchronous-physical-exchanges/blob/main/README.md

If you happen to remember the similar project you mentioned, I would also be interested in knowing its name. It could be useful to compare approaches. Please feel free as well to review the content and share your thoughts if any points raise questions or interest you.

Ucy:
I will now provide a more detailed response to the questions raised regarding the logistical commitment, its associated responsibilities, as well as the more detailed functioning of the nodes and layer B.

Regarding the transporter’s commitment, particularly in terms of insurance in case of loss or theft, it is important to clarify that this aspect does not fundamentally differ from what already exists today in traditional logistics systems. Transport operators already rely on insurance mechanisms, whether internal or through third-party insurers, depending on the nature and value of the goods being transported. In this context, risk management remains the responsibility of the logistics providers themselves, not the protocol. The system therefore does not introduce a new type of risk, but rather fits within a framework already mastered by transport actors. Concretely, these actors maintain financial reserves or risk-pooling mechanisms that allow them to cover potential losses, as is already the case today. This operates similarly to traditional insurance systems, for example in housing: not all claims occur at the same time, and the system relies on risk mutualization. If an extreme event were to occur simultaneously across all cases, no insurance system could cover all losses, yet this does not prevent such models from functioning effectively in practice. The principle remains the same here.

To avoid any situation in which an item would remain without handling after the buyer’s validation and payment, the system can rely on a set of logistics operators affiliated with the network. These operators, once registered within the infrastructure, accept the protocol rules as well as the cryptographic commitments associated with transport tasks. When an exchange is finalized and the item is locked in the deposit locker, the logistics task can be automatically assigned to one of these operators according to predefined rules. The corresponding cryptographic commitment is then triggered without requiring manual selection. This mechanism ensures that a validated and paid item is not left without a transporter.

Such a mechanism is not fundamentally different from practices already present in e-commerce. When placing an order online, the buyer may choose between several carriers or delivery levels, but once the order is confirmed, the transport task is automatically handled by the selected provider, without the provider individually accepting each package. In this model, logistics operators agree in advance to the protocol rules and associated commitment conditions, making automatic task assignment possible while ensuring process continuity.

Regarding the role of humans, it is indeed likely that current technological limitations still require some level of human intervention in certain cases. However, the objective of this model is precisely to minimize reliance on trust-based human mechanisms, moving toward a system where validation and execution rely primarily on cryptographic commitments and protocol rules rather than reputation or arbitration.
Finally, even with multiple witnesses and re-verification mechanisms, this still introduces forms of trust and potential coordination risks between participants. The goal here is to eliminate these dependencies by design, rather than attempting to mitigate them afterward.

System Compensation:

The system’s compensation relies on protocol fees integrated into the exchange and paid by the buyer, in addition to the logistics cost. These fees are intended to compensate both the logistics operator responsible for the physical transport and the nodes of the distributed infrastructure that ensure the operation of the state layer. Layer B does not constitute a monetary infrastructure and does not create value on its own. The compensation of participants relies exclusively on fees integrated into the underlying economic exchange. These fees, paid by the buyer during the transaction, are then redistributed between the logistics operators and the contributing nodes based on their effective participation.

Unlike systems based on competition or the designation of a single winner, layer B operates on a contribution-based compensation model. Nodes that actively participate in processing a given state—data reception and verification, cryptographic hashing, information propagation across the network, timely validation submission, and participation in the finalization of the state block—are identified by the protocol as contributing nodes.

For each validation sequence, the system records the actions performed by nodes (validation submitted, comparison executed, finalization signature, etc.) and builds a set of active participants. The fees associated with that state are then distributed among these contributing nodes, either equally or proportionally to their effective participation.
This mechanism ensures that nodes are compensated for the actual work performed, without introducing competition, lottery-based rewards, or arbitrary selection. It also enables continuous distribution of incentives, regardless of the rarity or frequency of events, in line with the non-monetary nature of layer B.
At the same time, the logistics operator is compensated through transport fees associated with the physical exchange and assumes, in return, the cryptographic commitment accepted when taking charge of the item.

Anchoring of States in Bitcoin:

To strengthen the resilience and integrity of the state registry, layer B can periodically anchor its data into the Bitcoin blockchain. Validated states are grouped and condensed using a cryptographic structure such as a Merkle tree. The root of this tree, which represents a unique fingerprint of all the associated states, can then be included in a Bitcoin transaction.

This mechanism allows the system to benefit from Bitcoin’s security and immutability while limiting the amount of data actually written to the blockchain. It is acknowledged that the use of the Bitcoin blockchain for anchoring external data should remain minimal so as not to unnecessarily increase the network’s data load, as its architecture is specifically designed to limit such growth. For this reason, anchoring can be performed by grouping states over a given period rather than on a per-transaction basis.

The objective is not to use Bitcoin as a storage layer, but as an external cryptographic reference that publicly attests to the existence and integrity of the states recorded by layer B.
As Bitcoin’s block subsidy decreases over successive halvings and is expected to disappear around 2140, miners will rely primarily on transaction fees to maintain network profitability. In this context, the use of the Bitcoin blockchain as an anchoring layer by external systems could contribute to supporting this fee-based economy.
This practice can increase demand for block space and therefore transaction fees, which may indirectly strengthen miners’ economic incentives. Within this model, the anchored data does not represent the content of physical exchanges themselves, but only a cryptographic proof that a validated event on layer B corresponds to a real operation associated with a transaction on layer A.
As such, this data maintains a direct link with a concrete economic activity. Unlike certain data that can be written to the blockchain without an explicit connection to an economic transaction, the goal here is to reference only real events resulting from an actual exchange.