Terminology

This page provides clear definitions of key rollup-related terms, particularly those associated with bonding mechanics in the Taiko Alethia protocol.

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Bonding Mechanisms in Taiko Alethia

Bonding is a fundamental mechanism in the proving and verification process of Taiko Alethia. Different types of bonds ensure that provers, contesters, and the network remain accountable for their commitments.

Liveness Bond

• A bond posted by the initially assigned block prover to guarantee that they will submit the first proof within the required proving window.
• Purpose: Ensures that the assigned prover remains active and submits the initial proof within the allocated time.
• Lifecycle:
  1. The L2 block proposer submits a block via proposeBlock on Ethereum L1.
  2. The assigned prover locks a Liveness Bond to signal commitment.
  3. If the prover submits the proof within the proving window, the bond is refunded.
  4. If the proof is not submitted within the proving window, another prover can step in, but they must provide a new Validity Bond.

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Validity Bond

• A bond submitted by the prover at the time of proving a block (proveBlock transaction). This bond guarantees that the prover stands by the correctness of their proof.
• Purpose: Protects the network from fraudulent or incorrect proofs by ensuring provers have economic skin in the game.
• Lifecycle:
  1. A prover submits a validity proof for a block.
  2. The Validity Bond is locked in the contract.
  3. If the proof is verified and uncontested, the bond is returned to the prover.
  4. If the proof is contested and found incorrect, the bond is slashed.

Note

If a new prover submits a proof after the initial proving window, they must post the full validity bond amount, regardless of whether the previous prover had posted a Liveness Bond.

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Contest Bond

• A bond submitted by a contester who believes an already proven block contains an invalid proof and should be escalated to a higher-tier proof system for validation.
• Purpose: Ensures that contesters only challenge proofs when they have strong evidence, preventing spam or frivolous disputes.
• Lifecycle:
  1. A prover submits a proof for a block.
  2. A contester submits a Contest Bond if they suspect the proof is invalid.
  3. The challenge escalates to a higher-tier prover for verification.
  4. If the higher-tier proof is valid, the contester forfeits their bond.
  5. If the higher-tier proof is invalid, the original prover’s Validity Bond is slashed, and the contester receives a portion of the slashed bond.

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Summary of Bonding Relationships

Bond Type	Submitted By	When Is It Locked?	When Is It Returned?	When Is It Forfeited?
Liveness Bond	Assigned Block Prover	Upon block assignment (proposeBlock transaction)	When the block is proved within the proving window	If proof is not submitted within the proving window
Validity Bond	Prover (any)	Upon proof submission (proveBlock transaction)	If the proof is uncontested and verified	If the proof is invalid and contested successfully
Contest Bond	Contester	Upon submitting a dispute against an existing proof	If the contested proof is found invalid	If the contested proof is verified as correct

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Key Takeaways

1. Liveness Bond ensures that the initial prover submits their proof on time.
2. Validity Bond guarantees that a submitted proof is correct and withstands scrutiny.
3. Contest Bond prevents frivolous challenges by ensuring contesters have an economic stake in their disputes.