Taiko Alethia nodes

Taiko Alethia nodes are minimally modified Ethereum execution clients that adhere to Ethereum’s execution-consensus separation model. The two primary components of a Taiko node are:

• taiko-geth (execution client)
• taiko-client (consensus client)

This architecture mirrors Ethereum’s execution/consensus split but replaces the consensus layer with Taiko’s own taiko-client. The taiko-client drives taiko-geth over the Engine API, allowing modular execution client compatibility.

Execution Layer: taiko-geth

taiko-geth is a fork of go-ethereum with minimal changes to support Taiko Alethia.

Functionality:

• Processes and executes L2 transactions from the Taiko mempool.
• Maintains state storage, transaction history, and receipts.
• Implements Ethereum-equivalence, ensuring all EVM opcodes behave identically.
• Supports modular execution by allowing future execution clients.

All modifications to go-ethereum can be reviewed in the Geth fork diff.

Consensus Layer: taiko-client

taiko-client acts as the consensus component, replacing Ethereum’s traditional beacon chain. It interfaces with taiko-geth using the Engine API.

Components:

driver

• Serves as the L2 consensus client.
• Monitors L1 events from TaikoL1 to detect proposed blocks.
• Directs the execution engine to insert or reorganize blocks through the Engine API.

proposer

• Collects pending transactions from taiko-geth’s txpool.
• Constructs batch-compliant txLists and submits them to TaikoL1.

prover

• Fetches proposed blocks from TaikoL1 and verifies them.
• Generates ZK/Secure Enclave proofs to validate state transitions.

Chain Synchronization Process

The Taiko Alethia consensus model differs from Ethereum’s due to its rollup-based structure.

1. Driver Initialization

   • Fetches the latest verified L2 head from TaikoL1.
   • Tries to sync state via P2P.
   • If P2P sync fails, inserts verified L2 blocks sequentially using the Engine API.
   • After catching up to the latest verified L2 block, proceeds to the following step.

2. Block Proposal Ingestion

   • Listens for TaikoL1.BlockProposed events.
   • Retrieves the transaction calldata from TaikoL1.proposeBlock.
   • Decompresses txListBytes and reconstructs block metadata.

3. Validation and Execution

   • If txList is valid, constructs an L2 anchor transaction and inserts the block.
   • If txList is invalid, constructs an empty L2 block.

Block Proposal Process

1. The proposer fetches pending transactions from taiko-geth.

2. If transaction volume exceeds the max txList size, transactions are split into batches.

3. The proposer submits TaikoL1.proposeBlock transactions, encoding the txList.

Block Proving Process

Once a block is proposed:

1. The prover retrieves the corresponding TaikoL1.proposeBlock transaction calldata.

2. It waits until the L2 execution engine has inserted the block.

3. The prover generates a validity proof.

For a valid or invalid txList, the prover:

1. Constructs a Merkle proof verifying the block’s txRoot.

2. Verifies the TaikoL2.anchor transaction in the Merkle Patricia Trie (MPT).

3. Submits:

   • TaikoL2.anchor transaction’s RLP-encoded bytes.
   • Merkle proofs.
   • Proof-of-validity to TaikoL1.proveBlock.

Even if the txList is invalid, proving ensures that invalid blocks are mapped to an empty anchor-only block.

Taiko Alethia Node APIs

A Taiko Alethia node exposes Ethereum-equivalent JSON-RPC methods, making it compatible with standard Ethereum tooling.

Differences from Ethereum Geth

• Modified Consensus Rules: Taiko uses taiko-client instead of a traditional beacon chain.

• Blob Data Handling: If EIP-4844 blobs are enabled, calldata is stored separately.

• Taiko-Specific Events: Includes TaikoL1.BlockProposed, TaikoL1.BlockVerified, etc.

For a complete diff, check the Geth fork comparison.

JSON-RPC API

Supports all standard Ethereum execution APIs. See Ethereum Execution API Docs.

Engine API

Manages consensus-execution communication. See Engine API Spec.

Hive Test Compliance

Taiko Alethia aims to pass the Ethereum Hive e2e test suite, ensuring API and execution consistency.

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