Hidden Validators

To bolster the security of the Zeknd Superchain, the concept of Hidden Validators is employed. These Hidden Validators form smaller committees assigned to each shard, typically consisting of around 100 validators. Their primary role is to verify the integrity of each chunk within their respective shards. However, unlike traditional validation mechanisms that publicly assign validators, Zeknd takes a different approach.

Rather than openly disclosing shard assignments on the blockchain, opZEKND leverages a technique where validators individually determine their assignments in a private manner. Using a Verifiable Random Function (VRF), each validator randomly draws a set of shard IDs, allowing them to know which specific shards they are responsible for verifying. This privacy-centric approach adds an additional layer of security to the network.

By employing this methodology, corrupting a Hidden Validator becomes significantly more challenging for adversaries. To compromise the system, an attacker would need to bribe a substantial number of validators across all shards to reveal their assignments, making coordinated attacks prohibitively difficult.

Moreover, opZEKND introduces an element of randomness in the selection of hidden validators assigned to a particular block. This prevents adversaries from accurately determining the number of hidden validators they need to corrupt to execute a successful attack. The lack of these information thwarts tactics where attackers could strategically plan their moves based on knowledge of validator assignments.

The verification process carried out by Hidden Validators enables any individual validator to present a proof known as a "fraud proof" if they detect any invalid chunks. This capability ensures the integrity of the network by allowing validators to expose fraudulent behavior.

The selection of the smaller per-shard committee, including Hidden Validators, occurs in every epoch, which spans approximately half a day. These committees are chosen from the same pool of nodes that participate as block and chunk producers. For instance, if there are 100 seats per shard and 100 shards, resulting in a total of 10,000 seats, 100 seats are allocated to chunk producers, while the remaining seats are assigned to Hidden Validators.

In summary, opZEKND's implementation of Hidden Validators introduces an innovative and privacy-focused approach to enhance the security of the network. By combining random assignment, private shard verification, and the ability to present fraud proofs, opZEKND ensures the integrity and resilience of its blockchain ecosystem.