What is TAC

TAC is a Network Extension for TON that expand its compatibility with the Ethereum Virtual Machine (EVM). It enables users to access EVM applications directly through their TON wallets, eliminating the need for managing multiple wallets or using traditional bridges.

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Key Features

Here are the key features of TAC and how they work:

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EVM equivalent Layer 1

The EVM equivalence in TAC is obtained running a fully fledged EVM Layer1 based on CosmosSDK + Ethermint, secured by dPoS and Babylon Bitcoin Staking. This TAC EVM Layer is the place where EVM code is deployed and executed to power TON Native-like dapps in the TAC ecosystem.

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Secure Cross-Chain Communication

At the heart of TAC is a decentralized sequencer network that ensures secure message delivery between TON and TAC EVM chains. This system implements multiple validation layers, where individual sequencers first validate transactions before groups reach consensus. The network requires 66% agreement within each group and further cross-group validation, creating a robust and secure communication channel between TON and TAC EVM chains.

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Economic Security Model

The network’s security on both the TAC EVM Layer and Message Bridge relies on real economic stake in the system. These groups of validators (EVM) & sequencers (Bridge) must stake collateral and actively participate in validation rounds. Good performance earns rewards, while incorrect operations face penalties. This economic model aligns incentives across the network, ensuring participants work to maintain security and efficiency.

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Proxy Apps

TAC provides a flexible approach to use or develop proxy smart contracts on both TON and EVM networks. These proxies handle all the complexities of cross-chain communication behind the scenes, making EVM apps feel native to TON users. When someone wants to interact with an EVM application, they simply use their TON wallet as they normally would - the proxy contracts take care of everything else.

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How TAC Works

TAC uses a multi-step process to enable seamless interaction between TON and EVM-based applications:

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Cross-Chain Messaging Process

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Epoch-Based Processing

TAC structures its transaction processing using epochs, a time-based system that ensures orderly processing of cross-chain messages. Each epoch is calculated using the formula:

EpochId = (now - protocolDeployDate) / epochDuration

Bridge Sequencers handle messages within specific timeframes defined by:

[protocolDeployDate + EpochId * epochDuration,
protocolDeployDate + (EpochId + 1) * epochDuration]

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TAC EVM Network Security

TAC is a ComsosSDK + Etheremint Layer 1 secured by Tendermint-Core and Babylon Bitcoin Staking. As such, the TAC EVM Layer inherit all the security aspects of Ethermint Cosmos chains.

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Bridge Network Security

TAC uses a combination of message validation and transaction protection to ensure the security of cross-chain transactions:

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Message Validation

Security starts with thorough message validation. Sequencers carefully index and validate all transferred assets, ensuring messages exactly match the actual transfers. This system prevents any potential misuse by ensuring target contracts can only access verified assets, with consensus mechanisms preventing double-spending attempts.

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Transaction Protection

TAC includes robust protection mechanisms for failed transactions. When a transaction fails, the system automatically returns assets to the sender and prevents forwarding to the target chain. A special rollback process handles these cases, ensuring user funds remain secure throughout the process.

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Developer Integration

Solidity developers that are interested in distributing their dApps as Native TON dApps in the TON ecosystem, have to focus only on the Frontend modifications. Solidity code can be deployed as-is on TAC EVM Layer using the common toolsets available for Ethereum Mainnet. The only difference lies in the frontend: having a Telegram MiniApp (TMA) is not mandatory, despite reccomended, but what is mandatory is to have a Frontend that uses TVM compatible wallets and is able to send transactions on TON network, targeting a Proxy App and paying fees on the TON network, in TON tokens.

TAC provides developers with a straightforward JavaScript SDK for the frontend integration. Here’s how simple it is to use:

const tacSdk = new TacSdk({
  network: CHAIN.TESTNET,
});

await tacSdk.sendJettonWithProxyMsg({
  fromAddress: userAddress,
  jettonAmount: amount,
  proxyMsg: {
    evmTargetAddress: targetAddress,
    methodName: "method",
    encodedParameters: params,
  },
});

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API Access

On the frontend side, developers can access the TON network through two public endpoints:

• Mainnet: https://toncenter.com/api/v2/jsonRPC
• Testnet: https://testnet.toncenter.com/api/v2/jsonRPC

To deploy Solidity code and directly access the TAC EVM Layer, developers can rely on public RPC endpoints that implements the standard EVM JSON-RPC interface:

• Mainnet: to-be-defined
• Testnet (Turin): [Coming Soon - later this week]

Third party providers like Anrk, offers private RPC endpoints and agumented APIs.

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Network Parameters

Here are the key parameters of the TAC EVM network:

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Testnet (Turin)

• ChainId: [Coming Soon - later this week]
• Blocktime: 4 seconds
• Explorer: [Coming Soon - later this week]

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Mainnet

• to-be-defined

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Bridge Consensus Architecture

The network operates on a carefully designed consensus system requiring 66% agreement within sequencer groups. This high threshold ensures security while maintaining efficiency. Cross-group consensus adds another layer of validation, with a 24-hour execution window providing ample time for transaction completion while maintaining network responsiveness.

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Bridge Economic Framework

TAC’s economic model centers on maintaining network security through financial incentives. The DAO sets minimum stake requirements for participants, while a performance-based reward system encourages reliable operation. Regular stake evaluations and a comprehensive penalty system ensure all participants maintain high standards of service.

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Sample Transaction Flow

Let’s walk through a real-world example of a user swapping tokens on an EVM DEX:

The process begins with Transaction Start, where a user connects their TON wallet to the DEX Frontend and selects the amount they want to swap. After approving the transaction, Cross-Chain Processing kicks in - the TON proxy locks their tokens and creates a cross-chain message. Sequencers detect this transaction and begin their validation process.

During Validation, groups form Merkle trees and work to reach consensus both internally and across groups. Once validated, the DEX Interaction phase begins. The EVM proxy receives the validated message, handles the necessary token operations, and executes the swap on the DEX. Finally, during Completion, the transaction confirms and the user receives their swapped tokens.

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Benefits

TAC creates value for multiple stakeholders in the blockchain ecosystem. Users gain the ability to use their familiar TON wallet while accessing the vast world of EVM applications deployed on the TAC EVM Layer, without dealing with complex bridging processes. Developers benefit from easy integration paths and automatic proxy generation, backed by secure cross-chain messaging and a comprehensive SDK.

For the broader ecosystem, TAC significantly increases TON’s utility by making EVM applications accessible to its users. The system’s security architecture and scalable design ensure it can grow with increasing demand while maintaining high security standards.