Introduction to Shield Node

A Shield Node is an observatory node within the Nanon Rollup protocol. Its primary function is to monitor the protocol and alert (by whichever means the operator chooses) if an incorrect block is proposed, allowing for intervention by others. The purpose of a Shield Node is to address the verifier's dilemma, ensuring that validations are correctly executed and false submissions are promptly identified and dealt with.

How Shield Node Work

Shield Nodes operate by registering as referees with the purchase of a Shield Node Key, enabling them to qualify to make statements against specific assertions. When the correct state root of an assertion is obtained—which will become the successor of a published assertion—Shield Nodes can make statements against the assertion if specific conditions are met, by invoking the referee. If a subsequent statement is created and confirmed, and the Shield has published the correct statement, it will contact the referee to issue a redemption transaction. The referee will verify several conditions before paying out rewards to the Shield.

Operational Conditions for Shield Node

Anyone can operate a Shield Node by downloading, installing, and running the necessary software. However, to be eligible for rewards, at least one Shield Node Key must be purchased. To claim accumulated rewards, two conditions must be met: a) the operators are not in the US, and b) they are not under any OFAC sanctions. Additionally, purchasing a Shield Node Key requires confirmation that doing so does not violate any local laws applicable to the purchaser. Rewards are not granted to Shield Nodes that do not run or fail to secure adequate funding to cover gas fees, so operators must ensure their nodes are well-funded, online, and operational.

Referee Smart Contract

The Referee Smart Contract plays a crucial role within the Nanon ecosystem, handling the management and validation of assertions made by Shield Nodes. Key functionalities of this contract include submitting assertions, claiming rewards, and creating assertion hashes to check payments. This contract allows Shield Nodes to submit assertions in response to challenges, and this function can only be invoked by the owner of a Shield Token or an address authorized by them on this contract. The contract also includes a function allowing users to receive rewards for successful assertions. This function checks whether submission for verification has been closed and, if conditions are met and the assertion is valid for payment, it satisfies the reward criteria. The Referee Contract ensures the integrity of the Nanon network by verifying assertions and rewarding successful ones, thus incentivizing Shield Nodes to monitor the network accurately and diligently.