We've standardised decentralisation assessment for Rollups. Now it's time to do the same for Validiums and Optimiums. Introducing: the Alt-DA Stages Framework - a structured path for off-chain data availability systems to earn trust. Forum post + community feedback open 👇

Quick background: in a rollup, DA lives on the L1, anyone can read Ethereum and verify state transitions themselves. In a Validium or Optimium, DA is off-chain. If the sequencer withholds data, fraud proofs can't be constructed, and Validium users are unable to reconstruct their state. So far the ecosystem has lacked a clear way to evaluate which Validiums and Optimiums are properly leveraging Ethereum’s security and censorship resistance and this framework aims to change that. Our new framework extends the L2BEAT Stages approach to evaluate Alt-DA systems, specifically bridging the gap between "reputation-based" security and actual decentralization. It proposes three stages 👇

Stage0⃣ We require a functional proof system and onchain decodable DA commitments. Without a proof system, the sequencer is trusted for everything. With it, the attack surface is narrowed, invalid state transitions are caught whenever data is accessible.

Stage 1⃣ The guiding principle here is: The only ways (other than bugs) to steal funds or block withdrawals indefinitely are: (1) compromising ≥75% of the Security Council to push a malicious upgrade, or (2) the sequencer colluding with the DA committee to withhold data and finalize invalid state roots. So the defining requirement is onchain verification. The L1 contract must verify DA attestations. This ensures that users can actually trust the DA layer and can exit without permissioned operators. The requirements for the exit window and forced transaction mechanism as defined in the rollups’ framework apply as well.

Stage 2⃣ The defining gate here is that DA must be backed by staked assets that are slashable upon misbehavior. This creates a true, economically secure layer - the highest standard currently possible for off-chain DA systems. Other than that, the rollups’ framework requirements apply.

An important note ❗️ While these stages mirror our Rollup Stages, they are not equivalent. An Alt-DA system carries an inherent extra trust assumption - the DA layer itself. Even at Stage 2, Alt-DA systems aim for economic security, not absolute trustlessness.

We invite the community, developers, and researchers to review the requirements and help us refine this standard. 🙏