Sequencer Network

The sequencer network is TAC’s decentralized off-chain system based on proof-of-stake that ensures reliable and secure message delivery between TON and EVM chains.

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Understanding Sequencers

Sequencers are nodes that form transaction trees, with one tree for TON and another for EVM. They use Merkle trees to organize cross-chain messages, collecting log messages from TON and events from the EVM side within specific time intervals set by the network.

A sequencer takes data from smart contracts, part of the execution layer, and aggregates transactions received over time T (a global network parameter). This organized approach ensures orderly processing of all cross-chain communications.

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Sequencer Groups

The network organizes sequencers into groups to enhance security and reliability. A sequencer group is a unified set of sequencer nodes owned by a specific entity - for example, each trusted dApp can have its own group.

• Within each group, sequencers independently form transaction trees and create Merkle proofs. They submit their root hashes to the SequencerGroup smart contract, where the system verifies the submitting wallet’s approval status.

• The signature counter for each proof increases as group members submit matching hashes. When signatures reach 66% of the group’s required threshold, the tree advances to the CrossChainLayer smart contract.

• At the CrossChainLayer level, groups must achieve network-wide consensus. The tree is only applied for cross-chain operations when enough groups submit identical trees, creating multiple layers of security.

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Becoming a Sequencer Group

Group formation isn’t open to everyone - it requires approval through multisig or DAO voting. Organizations managing a group can determine their internal sequencers using standard wallets or multisig for enhanced security. Future implementations may include a rating system affecting group collateral and profitability.

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Economic Security Model

Each group must maintain collateral above a minimum threshold determined by DAO voting. While collateral size doesn’t influence the signatures needed for tree establishment, it affects profitability. Higher collateral incentivizes better security through increased stake in the system’s success.

Groups can modify their collateral when changing proofs. If an incorrect proof is submitted, there’s time to issue penalties before collateral withdrawal. Other groups can submit penalty applications to the Penalty smart contract, with partial collateral locking if enough groups agree.

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Message Validation

The sequencer network ensures transaction integrity through comprehensive validation. When processing cross-chain messages, sequencers verify that:

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Executor Selection

Executors are sequencers chosen to process specific transactions in each execution round. Selection happens randomly but proportionally to each sequencer’s collateral - higher stake means more frequent selection and larger rewards.