IIP-31: Bridge Solana to IoTeX via ioTube


The proposal details the integration of Solana with the ioTube bridge, enhancing DEPIN interoperability. It specifies on-chain contracts for sending and receiving assets, the ioTube Message Protocol for event communication, and off-chain witness consensus using secp256k1 and ed25519 elliptic curves, optimizing cost and performance.


After integrating into EVM and Bitcoin ecosystem, Solana ecosystem is the next milestone for ioTube bridge. Bridging Solana and IoTeX chains will enhance interoperability between two leading DEPIN ecosystems, enabling seamless transfer of assets, data, and services. Once this bridge is complete, Solana DePIN tokens will be able to be bridged to the IoTeX L1. This allows Solana DePINs to expand their reach and benefit from IoTeX’s large, global community. As an example of this, IoTeX’s Liquidity Hub on the mimo DEX has had great success creating new liquidity pools for DePIN tokens on other chains (Polygon, Ethereum) and we look forward to offering this benefit to Solana DePIN projects. Enhanced interoperability will attract a broader user base, driving adoption and network effects while promoting the overall growth of the DEPIN sector. Additionally, as one of the public goods of IoTeX ecosystem, ioTube bridge is evolving to create a more interconnected and impactful DEPIN ecosystem, aligning with our mission of “DePIN for Everyone.”


Onchain Contracts

Methods of Sending Assets

These methods enable blockchain clients to bridge assets from the source chain to the destination chain. User assets are locked in a token safe within the contract by the bridge, which can only be withdrawn by burning the wrapped assets on the destination chain.

  • Method on Solana Chain:
pub fn process_bridge(program_id: &Pubkey, accounts: &[AccountInfo], amount: u64, to: &[u8]) -> ProgramResult
  • Method on IoTex Chain:
function depositTo(address _token, address _to, uint256 _amount) public whenNotPaused payable

Methods of Receiving Assets

These methods allow off-chain relayers of the bridge to submit proofs, confirmed by witnesses (oracles) regarding events emitted on the source chain, to the contract on the destination chain. Proofs are submitted automatically by relayers. Once verified, bridged assets are issued to the user’s wallet (assets will be sent to users’ associated token account on Solana).

  • Method on Solana Chain:
 pub fn process_settle(program_id: &Pubkey, accounts: &[AccountInfo], amount: u64) -> ProgramResult
  • Method on IoTex Chain:
function submit(address cashier, address tokenAddr, uint256 index, address from, address to, uint256 amount, bytes memory signatures) public whenNotPaused 

ioTube Message Protocol

The ioTube Message Protocol is adopted by on-chain contracts of ioTube bridge as the format of emitted events to ensure interoperability between the IoTeX chain, the Solana chain, and off-chain witnesses:

Receipt struct {
    token Address, 
    id Number, 
    sender Address,
    recipient Address, 
    amount Number, 
    fee Number,

Offchain witnesses concensus

Solana-IoTeX bridge, leveraged on the ioTube Bridge architecture, operates on the existing witnesses network with Solana client support. Once two-thirds of witnesses sign the event, a consensus is reached, and the relayer submits the data and signatures to the contract. When bridging assets from Solana to IoTeX, witnesses use the secp256k1 elliptic curve to sign the data, which can be verified in EVM smart contracts; in the opposite direction, the ed25519 elliptic curve is used.



Ed25519 Elliptic Curve

The address of a Solana account is a public key lies on the ed25519 curve. Therefore, to be seamlessly managed in the Solana program of the bridge, each off-chain witness possesses an ed25519 private key as their identity. Additionally, Ed25519 signatures can be natively verified by the system program Ed25519SigVerify111111111111111111111111111, significantly reducing the bridge’s operational costs.

Backward Compatibility

The change will ensure seamless integration with existing infrastructure, including UI/UX enhancements to include a Solana option and compatibility with the smart contracts on IoTeX.

Security Considerations

There is no security concern.


Copyright and related rights waived via CC0.


This is an awesome initiative to further extend the IoTeX reach into the greater DePIN ecosystem.

Solana + IoTeX = A major win for DePIN

1 Like

I want to see Avanche Depin niche collab
with iotex if they have any.

I can’t wait :heart_eyes:. Exciting developments ahead :mechanical_arm: