> For the complete documentation index, see [llms.txt](https://moon-ton.gitbook.io/moon-ton/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://moon-ton.gitbook.io/moon-ton/technical-overview/bridge-architecture.md).

# Bridge Architecture

MoonTON stands as an innovative platform meticulously crafted to facilitate secure and efficient token exchange among Ethereum, Solana, and TON blockchains. Its bridge architecture is founded upon advanced technologies and robust security mechanisms, rendering it a dependable instrument for cryptocurrency users seeking seamless interoperability across blockchain networks.

<figure><img src="/files/hgO4CVGJx2rYLSRkztKN" alt=""><figcaption></figcaption></figure>

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**Example of Bridge Operation: Solana-TON**

Overview:

The Solana-TON bridge enables the bidirectional transfer of tokens between the Solana and TON blockchains. It uses a lock-and-mint mechanism where tokens are locked in a bank contract on the source chain, and a wrapped version is minted on the destination chain. A multisig committee provides attestations to ensure the validity and security of the transfers.

Components:

1. Solana SPL Token Vault: A smart contract on Solana that locks SPL tokens to be transferred to TON. It supports multiple SPL token types and emits a lock event with the relevant details, including the token type and amount.
2. TON Bank Contract: A smart contract on TON that locks native tokens to be transferred to Solana. It emits a lock event with the relevant details.
3. Solana SPL Token Mint Contract: Mints wrapped TON tokens as SPL tokens on Solana upon receiving a valid attestation from the multisig committee. It maintains a mapping of the wrapped token type to the corresponding TON token type. Burns wrapped tokens when unlocking.
4. TON Mint Contract: Mints wrapped Solana SPL tokens on TON upon receiving a valid attestation from the multisig committee. It maintains a mapping of the wrapped token type to the corresponding Solana SPL token type. Burns wrapped tokens when unlocking.
5. Multisig Attestation Committee: A set of trusted entities that run nodes to monitor lock events from the token vaults and bank contracts. They sign attestations validating the lock events and submit them to the mint contracts.

Transfer Flow (Solana SPL to TON):

1. User sends SPL tokens to the Solana SPL Token Vault.
2. Solana SPL Token Vault locks the tokens and emits a lock event, including the token type and amount.
3. Multisig committee validators detect the lock event.
4. Validators sign an attestation validating the lock details.
5. Attestation is submitted to the TON Mint Contract.
6. TON Mint Contract verifies the multisig attestation.
7. If valid, wrapped Solana SPL tokens are minted to the user's address on TON, according to the token type mapping.

Transfer Flow (TON to Solana SPL):

1. User sends native TON tokens to the TON Bank Contract.
2. TON Bank Contract locks the tokens and emits a lock event.
3. Multisig committee validators detect the lock event.
4. Validators sign an attestation validating the lock details.
5. Attestation is submitted to the Solana SPL Token Mint Contract.
6. Solana SPL Token Mint Contract verifies the multisig attestation.
7. If valid, wrapped TON tokens are minted as SPL tokens to the user's address on Solana, according to the token type mapping.

Unlocking (Solana SPL):

1. User burns their wrapped TON SPL tokens on Solana.
2. Burn event is detected by the Solana SPL Token Vault.
3. Solana SPL Token Vault unlocks the corresponding native TON tokens to the user.

Unlocking (TON):

1. User burns their wrapped Solana SPL tokens on TON.
2. Burn event is detected by the TON Mint Contract.
3. TON Mint Contract unlocks the corresponding native SPL tokens to the user on Solana.

#### Additional Considerations

* The Solana SPL Token Vault and Mint Contract need to handle multiple SPL token types and maintain accurate mappings to the corresponding wrapped tokens on TON. Similarly, the contracts must support the mappings for wrapped ERC-20 tokens on Ethereum.
* The TON Mint Contract needs to support minting and burning of wrapped Solana SPL tokens, as well as wrapped ERC-20 tokens, based on the token type mappings.
* The bridge ensures that the total supply of wrapped tokens on each chain matches the locked supply of the native tokens on the originating chain, for each token type.

#### Security Measures

* Multisig committee with a high threshold to prevent rogue attestations.
* Validators are required to stake funds that can be slashed for malicious behavior.
* Thorough testing and auditing of all smart contracts.
* Monitoring for anomalous events and the ability to pause contracts if needed.
* Time-locks on unlocking to allow for challenges and resolving disputes.

This design uses a multisig committee as a trust-minimized middle layer to attest lock events, enabling secure bidirectional token transfers between Solana and TON, as well as between TON and Ethereum, with protections against counterfeiting or invalid mints. The native tokens remain fully backed on their original chain while users can utilize wrapped versions on the other ecosystem.

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