Quote from: Serge V. on January 14, 2015, 01:21:30 PM

Reliable purchase/sell (also applicable for accounts) escrow scheme in which seller and buyer can't have any motivation to cheat each other (tested on DOGE):

1. Escrow agent creates 2-of-2 MultiSig address from Buyer and Seller pubkeys.
2. Buyer sends 2x coins to MultiSig address (buyer collateral + buyer payment for goods).
3. Seller sends 1x coins to MultiSig address (seller collateral).
4. Seller sends goods to buyer.
5. Buyer receives the goods and informs the escrow agent.
6. Escrow agent prepares 1x coins tx from MultiSig address to buyer (buyer collateral) and 2x coins to seller (seller collateral + buyer payment for goods).
7. Buyer and seller checks and signs tx, 1x coins goes back to buyer and 2x coins goes to seller.

Seller is interested to send the goods to buyer because he can lose an amount equal to value of the goods.
Buyer is interested to release the funds after getting the goods, otherwise he can lose an amount equal to value of the goods.
Collateral will encourage both sides to be honest, and if something happens with the parcel to conduct a thorough investigation and find consensus.

My first question to this would be why we need an escrow agent at all in this scheme. He has no power and doesn't do anything that the buyer or seller couldn't do.

My second question is what happens if the seller is a scammer, and doesn't send any coins in step 3? The buyer has just lost 2x his coins and has no chance of getting them back if the scammer doesn't cooperate. The scammer can make a transaction paying 1.9x coins to himself and 0.1x coins to the buyer. The buyer has to choose between signing the transaction and getting 0.1x coins back or not signing it and getting 0 coins back.