Chain Code Delegation: Private Access Control for Bitcoin Keys

OpenBazaar employed a unique protocol to facilitate secure and private transactions between buyers and sellers, leveraging the power of cryptocurrency technology. At the heart of this system was the use of a static public key posted by moderators, individuals who would oversee transactions only in cases of disputes. This approach allowed for a high degree of privacy, with transactions occurring without the moderator's knowledge unless their intervention was necessary.

The process began when both parties involved in a transaction agreed on selecting a moderator to oversee their deal. Following this agreement, they would decide on a specific chaincode to associate with their transaction. This chaincode played a crucial role, as it was used to tweak the moderator’s key and incorporate it into a specialized script. This script was designed to offer two paths for the transaction: a 2-of-2 path, known as the "happy path," which required consensus from both the buyer and seller for the transaction to proceed smoothly; and a 2-of-3 "dispute" path, which came into play if there were any issues during the transaction. The dispute path included the tweaked moderator’s key, enabling the moderator to step in and make a decision if the parties could not agree.

In essence, this protocol ensured that all transactions remained private under normal circumstances. The moderator's involvement was triggered only when a dispute arose, at which point they were provided with the chaincode and pertinent transaction information. This allowed them to impartially determine which party was entitled to the funds, based on the evidence presented. This innovative approach offered by OpenBazaar represents a significant advancement in ensuring secure, private, and fair digital transactions. For more details, one can refer to the project on GitHub at OpenBazaar.