How does the bitoftrade Cross-Chain Messaging Protocol (CCMP) work?

Cross Chain Messaging Protocol consists of 3 steps:

 

• Emit event on the SRC chain

• Verify the event and get proof from the Signer

• Receive the event on the DEST chain

 

Signer Service is responsible for producing proofs, whereas Signers Registry smart contract is responsible for validation if proof was made by the correct Signer.

 

Signer Service

 

Signer service is used to verify specific events. By request the service produces the proof for events. Proof of the event is a signature created by the signer's address.

 

Under the hood, Signer could implement any protocol to sign messages.

 

To create an event signature Signer signs a specific eventHash.

 

After the signature was generated, it could be used on your smart contract to verify the event. After successful verification, you could trust this event and do your dApp logic.

 

See the Signer Interface page to get endpoint params to sign the event.

 

You could also interact with our public Signer.

 

Event Hash

eventHash is calculated from the eventId and eventArgs:

 

 

eventId is the event params combined together to create a unique id.

 

where:

• EventName - the name of the event

• EventChainId - chainId of the transaction with invoked event

• EventContract - a contract that invoked the event

• EventTransactionHash - hash of the transaction with invoked event

EventArgs is the event's arguments. All event arguments will be combined in the same order as they were in the event.

 

 

 

For example, for this Transfer event, eventHash will be:

 

 

Signer interface

Each Signer implements an interface.

 

Metadata

 

GET /metadata the endpoint returns an object with the following type:

 

 

Where:

• name is the human-recognizable name of the signer

• availableChains is the list of supported chains

• signer is the address which is used to sign messages

   

Sign event

 

 

POST /sign-event the endpoint which is used to get proof of the event.

This endpoint requires a request body with the following type:

 

 

 

Where:

• chainId and txHash are from the transaction that has the event

• abi is the ABI of the event

• eventLogIndex (optional) - parameter that specifies the log index for the event. By default, the first event-matched ABI will be selected.

   

The response body will have the following type:

 

Where:

• eventHash - hash of the event

• signature - is signed eventHash by the signer

• params - list of the params, eventId and eventArgs

   

Signers Registry Contract

Signers Registry contract is used by other smart contracts to verify if the signature was created by the whitelisted signer. This smart contract has to be deployed on each supported chain.

 

Signers Registry implements this interface:

 

 

The signer could be public or private.

• Anyone can use the public signer for supported chains.

• The Private signer could be used for specific dApps, chains, etc. Such signers are restricted and closed for the community. Contact us if you want to implement a private signer.

   

See the example to understand how to use Signers Registry smart contract.

 

See deployed smart contract on explorer.

 

Signers Registry Smart contracts