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Universal Bridge

Overview​

Universal Bridge is the asset-transfer and settlement layer used across Sepolia and Ethera rollups. It provides the bridge flows used to move value between Sepolia and the rollups, and between the rollups themselves.

It is the bridge and settlement stack provided by Ethera and the recommended way to build. It is a reference implementation, not a required bridge design for every deployment.

It relies on the broader architecture described in these sections:

Supported Routes​

Universal Bridge supports three route families:

  1. Deposits from Sepolia into Ethera rollups
  2. Transfers between Ethera rollups
  3. Withdrawals from Ethera rollups back to Sepolia

These routes are implemented through different bridge contracts, and they follow Ethera's general model:

  • Canonical assets are escrowed or settled on Sepolia when required
  • Token representations are minted or burned on rollups when required
  • Cross-rollup communication is carried through the mailbox layer

Token Representation Model​

Universal Bridge does not treat an asset as one identical token across every chain. Instead, it tracks asset identity and materializes the correct representation where needed.

At a high level, builders should think in terms of:

  • Canonical assets on Sepolia
  • Native assets on a rollup
  • Wrapped CET, created when an asset needs a rollup representation
  • Core CET, representing the canonical form of an asset on its home chain

If an asset does not already exist on the destination rollup, the bridge can create the appropriate token representation automatically. In many cross-rollup cases, this means deploying or minting CET on the destination rollup.

Atomicity​

Universal Bridge relies on Ethera's atomic cross-rollup execution model. For the broader coordination model behind atomicity, see Synchronous Composability.

In bridge flows, this means ordered steps can still exist, but supported cross-rollup actions are coordinated as one atomic operation rather than as disconnected independent transactions.

Stack and Implementation​

The following pieces are part of Ethera Network and are foundational to Ethera's coordination model:

  • Mailbox-based cross-rollup messaging
  • Shared Publisher coordination
  • Two-Phase Commit for atomic cross-rollup execution

The following pieces are modular implementation choices built on top of that foundation:

In practice, this means Ethera's mailbox-based coordination model is part of the stack itself, while the bridge contracts documented in these docs are the reference implementation for the bridge and settlement layer.