Epic: P2P Apartment Rental (like AirBNB)

[Flaxscrip]

Author: Sat - community contribution

The Components and Their Roles

• Keychain/MDIP (DID & VC): Manages identity and authorization. The Verifiable Credential (VC) is the "smart key" that proves who you are and what your rights are.
• L402 Token: Manages the initial, non-refundable payment (the rental fee).
• Lightning HODL Invoice: Manages the conditional, refundable payment (the security deposit). This is a special type of Lightning invoice where funds are locked in escrow for a period.
• The Smart Lock: A DID-aware piece of hardware that acts as the physical gatekeeper.

The Lifecycle of a Decentralized Rental

Here’s the step-by-step process:

Phase 1: Booking and Payment

• **Discovery & Identity: ** You (the "Guest") find a property on a decentralized listing service or the owner's website. You connect with your DID, proving you control a stable identifier without revealing personal information.

• **Payment Request: ** The property owner's server issues two separate payment requests:

1. An L402 token request for the non-refundable rental fee (e.g., $300 for 2 nights).
2. A Lightning HODL Invoice for the security deposit (e.g., $500).

• **Payment Execution:

1. You pay the L402 invoice, proving you've paid the rent.
2. You pay the HODL invoice. Your wallet locks the $500. The funds have left your wallet but the owner cannot claim them yet. The funds are held in limbo on the Lightning Network, set to automatically return to you after the rental period ends (e.g., in 72 hours).

Phase 2: Issuing the "Smart Key"

• *Credential Issuance: Once the owner's server confirms both payments, it issues a Verifiable Credential to your DID. This "Rental Access VC" is your digital key and contract. It contains:

        subject: Your Guest DID.
        issuer: The Owner's DID.
        propertyId: A unique identifier for the rental property.
        validFrom: The check-in timestamp (e.g., 3:00 PM on Friday).
        validUntil: The check-out timestamp (e.g., 11:00 AM on Sunday).
        depositProof: A reference to the HODL invoice payment hash.

Phase 3: Accessing the Property

1. Arriving at the Door: You arrive at the property. The smart lock on the door is connected to the internet and controlled by the owner's DID.

2. Challenge-Response: You open your wallet app on your phone.

3. The app detects the lock via Bluetooth or NFC.

4. The lock issues a challenge (a random string of data).

5. Your wallet presents the Rental Access VC and signs the challenge with your DID's private key.

6. Verification by the Lock: The smart lock receives this information and instantly verifies everything:
   - Was this VC issued by the owner of this lock? ✅
   - Is it being presented by the legitimate guest the VC was issued to? (Verifies the signature). ✅
   - Is the current time within the validFrom and validUntil window? ✅
   - Has this VC been revoked by the owner? (Checks a revocation list). ✅

7. Unlock: If all checks pass, the physical lock clicks open. You have access. You can repeat this process as many times as you need during your stay.

Phase 4: Checkout and Deposit Return

• Automatic Expiration: Once the validUntil timestamp passes, the lock will automatically reject any further attempts to use your VC. Your key has expired.
• Automatic Deposit Return: Simultaneously, the HODL invoice for your security deposit expires. The $500 is automatically released and returns to your Lightning wallet. The default state is that the guest gets their money back.
• Handling Disputes (Claiming the Deposit): What if you broke a window?

Before the HODL invoice expires, the owner would need to take action. They would use their private key to claim the locked funds. To do this, they would need the "preimage" (the secret) from the HODL invoice.

The system could be designed so that the owner only receives this secret if they submit proof of damages to an agreed-upon arbiter, or if the guest cryptographically signs a message admitting fault.

This creates a trust-minimized escrow system without a bank or central platform holding the funds.

What This Model Achieves

• Disintermediation: It completely removes the need for a central platform like Airbnb. Owners and renters can interact directly, saving on fees.
• Automation: The entire check-in/check-out and payment/refund process is automated through cryptographic rules. No more manual key handoffs or chasing security deposits.
• Security: Eliminates physical keys that can be copied. Access is tied to a user's unforgeable cryptographic identity.
• Privacy: The guest doesn't need to share their legal name, email, or other PII with the owner, just their pseudonymous DID.
• True Ownership: The guest holds their own "key" (the VC) in their own wallet. The owner has direct control over their property's access rules.