Biconomy Cross Chain Messaging Protocol (CCMP)
This repository contains the smart contracts for Biconomy's CCM Protocol.
Introduction
CCMP faciliates cross-chain transfer of messages via Biconomy's network of decentralized relayers.
With CCMP, smart contracts deployed on one chain are able to execute arbitrary logic on another chain, while also transferring value (ERC20 tokens) via Biconomy's Hyphen Bridge.
Usage
To send a "message" to another chain, smart contracts will interact with the CCMPGateway
contract, specifically call the sendMessage
function as follows:
/// @param _destinationChainId The chain id of the destination chain.
/// @param _adaptorName The name of the router adaptor to use. Currently "axelar", "wormhole" and "abacus" are supported.
/// @param _gasFeePaymentArgs Contains details for the fee quoted by the relayer.
/// @param _routerArgs Contains abi encoded router specific arguments. For ex, CONSISTENCY_LEVEL when sending message via wormhole.
/// @return sent The hash of the message sent.
function sendMessage(
uint256 _destinationChainId,
string calldata _adaptorName,
CCMPMessagePayload[] calldata _payloads,
GasFeePaymentArgs calldata _gasFeePaymentArgs,
bytes calldata _routerArgs
) external payable;
The _payloads
argument is an array of the following form:
[
{
// Address of contract on the destination chain
address to;
// Calldata to execute on 'to'
bytes _calldata;
},
{
address to;
bytes _calldata;
},
{
address to;
bytes _calldata;
}...
]
Overview
Scenario: A smart contract 0xCONTRACT
on ethereum wants to send a cross-chain message to 0xCONTRACT
on Polygon.
Source Chain
-
0xCONTRACT
on ethereum prepares the requiredpayload
to be executed om polygon (calldata), selects an underlying protcol supported by CCMP and calls0xCCMPGateway.sendMessage
. The fee required to execute the message on the exit chain is assumed to be negotiated previously b/w the sender and relayer and the required payment mode is sent asgasFeePaymentArgs
along with the actual tokens are sent with the same call. -
0xCCMPGateway
will do some validations and pass on the message to0xCCMPExecutor
. -
0xCCMPExecutor
verifies the fee payment and does some accounting so that fee can be claimed later by the executor. In case there are any token transfer via Hyphen involved,0xExecutor
will perform the token deposits into existingHyphen
Liquidity Pools as well. -
0xCCMPGatway
calls the underlying protocol's adapter which sends the message to the exit chain.
Intermediate Off-Chain Steps
- In case the underlying protocol requires a fee payment for the message to be sent to the destination chain, the relayer will pay the fee to the underlying protocol on the user's behalf. This fee is assumed to be accounted for in the original fee negotiation b/w the user and the relayer.
- The relayer the waits for the message to be confirmed on the destination chain by the underlying protocol.
- Once the message is confirmed, the relayer calls
0xCCMPGateway
on the destination chain.
Destination Chain
-
0xCCMPGateway
calls the underlying adapter to verify the message with the underlying protocol. - The message is passed on
0xCCMPExecutor
, which executes the contract calls and Hyphen Token Transfers included in the original payload.