The Based Sovereign Rollup

The Based Sovereign Rollup

Like all Ethereum rollups, Facet’s state is derived from Ethereum L1 transaction history. However, Facet's fork of OP Stack incorporated key mechanisms from other existing Based Rollup and Sovereign Rollup architectures, resulting in a novel construction:

A BASED SOVEREIGN ROLLUP is a blockchain whose state is derived from transactions sequenced by L1 validators, with no dependency on privileged keys or enshrined contracts.

This new construct is the natural outcome of three design decisions that were necessary to preserve Ethereum's liveness, censorship resistance, and credible neutrality:

  1. Removal of all forms of privilege (e.g., upgradeable contracts, security councils, etc.).

Elimination of Centralized Dependencies

Facet replaces OP’s centralized sequencer with a Based Rollup sequencing mechanism, adopting regular Ethereum transactions as the default method for submitting Facet transactions (similar to OP’s “deposit transactions”).

In a conventional rollup, users send their transactions on a separate network to centralized sequencers, giving a single entity (or set of permissioned EOAs) control over the transaction history relevant to the rollup.

Facet returns control over transaction history back to Ethereum’s validators with a decentralized sequencing mechanism that ensures transactions are ordered fairly and impartially, allowing the rollup to inherit the L1’s native resilience to censorship, reordering attacks and single-party MEV exploitation. This approach, known as "Based Sequencing," affords everyone equal ability to post transactions to the rollup's history.

A rollup is said to be "based," or L1-sequenced, when its sequencing is driven by the base L1. More concretely, a based rollup is one where the next L1 proposer may, in collaboration with L1 searchers and builders, permissionlessly include the next rollup block as part of the next L1 block.

- Justin Drake

Removal of All Forms of Privilege

While a based sequencing mechanism certainly enhances a rollup's ability to preserve Ethereum's liveness, censorship resistance and credible neutrality, it's not enough on its own.

Current rollups make their rules in a far more centralized and less secure way than the underlying Ethereum protocol itself. Every L2 currently involves a set of privileged private keys (the "security council" or multi-sig) that is capable of changing the rules of the rollup by fiat.

Facet adopts Sovereign Rollup principles by eliminating these privileged keys (e.g., security councils, multi-sig wallets) from the protocol, thereby avoiding the centralization risks that plague traditional rollups (e.g., bridge security, contract upgradeability, etc.). Facet’s purge of privilege is indiscriminate, even removing the enshrined (built-in) gas token bridge. This ensures a core protocol void of centralized authority of any kind, while still allowing developers to offer trust-minimized bridging at the application level.

Of course, eliminating upgradeable contracts and privileged keys necessitates a novel approach to "gas"—which we'll cover below.

Issuing Gas Tokens Neutrally

Gas payments are an essential part of a blockchain network's operations, playing a crucial role in preventing network spam attacks. Unfortunately, L2s introduce privilege via their native gas token. They do so by enshrining a mandatory bridge in the protocol: the ether gas token bridge. Users must deposit ether into an L1 bridge contract managed by the protocol in order to mint gas tokens on the L2. This gas bridge is operated by the L2's privileged keys (security council), granting the protocol operators incredible advantage/control within the network (upgradeability, fork-choice influence, etc.). Thus, adoption of these L2s inherently comes at the expense of L1 censorship resistance and credible neutrality.

To avoid introducing privilege via a native gas token, Facet adopts a mechanically neutral issuance mechanism for the native gas token: Facet Compute Token (FCT). Anyone can participate in minting FCT on Facet simply by sending Facet transactions on L1 Ethereum. There are no enshrined bridge contracts and no privileged keys that alter Facet's immutable FCT issuance mechanism. Moreover, there are no pre-mined or privileged allocations.

Conclusion

By addressing key vectors of centralization and privilege introduced by conventional rollups, and by distributing the protocol's native gas token in a transparent, mechanically neutral way, Facet offers a way to scale Ethereum without sacrificing the very principles that make it special.

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