The identity layer includes a series of Smart Contracts also known as Registry Contracts used to manage accounts, each account's memory, and keys stored Onchain on Optimism. The username will be managed Offchain for the namespace operated by Farcaster or Onchain with a domain name from a third party such as ENS. For the Registry Contract, there are 3 main Smart Contracts:

Id Registry: Issue fids to create new accounts on Farcaster.

Storage Registry: Rent storage units for an annual fee. Each account must have at least one storage unit to publish messages on Farcaster.

Key Registry: Allows each account to register signers for their activities on social networks such as posting Posts, Likes, ...