š
Original date posted:2021-02-11
š Original message:
Good morning Nadav and Andres,
Thank you for bringing up this topic again.
Let me provide a new twist to this old idea.
This is the entire logic of the contract to the seller:
SELLER && (BUYER || ESCROW)
Now, a big issue is that simple `&&` is trivial for PTLCs, it is the `||` which is difficult and requires ECDH and proof that the ECDH was done correctly.
But we can observe the De Morgan Theorem:
A || B <=> !(!A && !B)
So how about we *invert* the logic?
So what we do is, we make *two* payments of the same amount:
* Seller -> Buyer , claimable by BUYER && ESCROW key.
* Buyer -> Seller, claimable by SELLER key.
So the ritual is this:
* Seller -> Buyer claimable by BUYER && ESCROW.
* Buyer -> Seller claimable by SELLER.
* Seller hands over item.
* Buyer judges whether to accept, or complain to Escrow.
Now let us consider our cases:
* Buyer is satisfied with the product.
* Buyer fails the Seller->Buyer payment after seller claims the Buyer->Seller payment, so Seller is paid and has no more obligations.
* Buyer is dissastisfied and wants the Escrow to judge:
* Escrow judges Buyer is right: Escrow reveals ESCROW key to Buyer, who then clawbacks the payment to the seller.
* Escrow judges Seller is right: Escrow deletes ESCROW privkey ("not ESCROW"), and the Seller->Buyer payment eventually times out, ending the obligation of the Seller.
The "reverse" payment is effectively the inversion of logic by the De Morgan theorem, and the "normal case" (buyer ultimately pays seller) has the Escrow not revealing the privkey.
In addition, in the case where Buyer is satisfied (i.e. both Buyer and Seller agree the trade is beneficial) the Escrow is never involved (the Escrow might have a timeout for the temporary ESCROW keypair, which it will eventually delete; since all payments on LN need a timeout anyway, this is fine) and thus does not know about the trade, except that some trade was requested (since it must provide a temporary ESCROW pubkey).
This even provides a simple BUYER + ESCROW keypair that gives the seller a proof-of-refund, and of course the simple SELLER gives the buyer a proof-of-payment as well.
It only just requires twice as much Bitcoins getting locked.
Thoughts?
Regards,
ZmnSCPxj
ZmnSCPxj [ARCHIVE] /
npub1g5ā¦3ms3l
2023-06-09 13:01:59
in reply to nevent1qā¦vkxq
Author Public Key
npub1g5zswf6y48f7fy90jf3tlcuwdmjn8znhzaa4vkmtxaeskca8hpss23ms3lPublished at
2023-06-09 13:01:59Event JSON
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Original date posted:2021-02-11\nš Original message:\nGood morning Nadav and Andres,\n\nThank you for bringing up this topic again.\n\nLet me provide a new twist to this old idea.\n\nThis is the entire logic of the contract to the seller:\n\n SELLER \u0026\u0026 (BUYER || ESCROW)\n\nNow, a big issue is that simple `\u0026\u0026` is trivial for PTLCs, it is the `||` which is difficult and requires ECDH and proof that the ECDH was done correctly.\n\nBut we can observe the De Morgan Theorem:\n\n A || B \u003c=\u003e !(!A \u0026\u0026 !B)\n\nSo how about we *invert* the logic?\n\nSo what we do is, we make *two* payments of the same amount:\n\n* Seller -\u003e Buyer , claimable by BUYER \u0026\u0026 ESCROW key.\n* Buyer -\u003e Seller, claimable by SELLER key.\n\nSo the ritual is this:\n\n* Seller -\u003e Buyer claimable by BUYER \u0026\u0026 ESCROW.\n* Buyer -\u003e Seller claimable by SELLER.\n* Seller hands over item.\n* Buyer judges whether to accept, or complain to Escrow.\n\nNow let us consider our cases:\n\n* Buyer is satisfied with the product.\n * Buyer fails the Seller-\u003eBuyer payment after seller claims the Buyer-\u003eSeller payment, so Seller is paid and has no more obligations.\n* Buyer is dissastisfied and wants the Escrow to judge:\n * Escrow judges Buyer is right: Escrow reveals ESCROW key to Buyer, who then clawbacks the payment to the seller.\n * Escrow judges Seller is right: Escrow deletes ESCROW privkey (\"not ESCROW\"), and the Seller-\u003eBuyer payment eventually times out, ending the obligation of the Seller.\n\nThe \"reverse\" payment is effectively the inversion of logic by the De Morgan theorem, and the \"normal case\" (buyer ultimately pays seller) has the Escrow not revealing the privkey.\nIn addition, in the case where Buyer is satisfied (i.e. both Buyer and Seller agree the trade is beneficial) the Escrow is never involved (the Escrow might have a timeout for the temporary ESCROW keypair, which it will eventually delete; since all payments on LN need a timeout anyway, this is fine) and thus does not know about the trade, except that some trade was requested (since it must provide a temporary ESCROW pubkey).\n\nThis even provides a simple BUYER + ESCROW keypair that gives the seller a proof-of-refund, and of course the simple SELLER gives the buyer a proof-of-payment as well.\nIt only just requires twice as much Bitcoins getting locked.\n\nThoughts?\n\nRegards,\nZmnSCPxj",
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