CCIP v2.0.0 MessageV1Codec API Reference

MessageV1Codec defines the canonical binary encoding format for CCIP V1 messages and token transfers.

It is used to:

• serialize messages on the source chain
• deserialize messages on the destination chain
• ensure consistent message hashing and verification

All cross-chain message integrity depends on this encoding.

This library provides reusable helper functions and is not deployed as a standalone application-facing contract.

Usage Boundary

You do not call this library directly.

• CCIP contracts use this library to encode and decode message payloads.
• OnRamp encodes messages before emission.
• OffRamp decodes messages before execution.
• You may use this library for debugging or custom integrations.

Contract

libraries/MessageV1Codec.sol

Import

import {MessageV1Codec} from "chainlink-ccip/libraries/MessageV1Codec.sol";

Functions

All functions are internal and pure.

_computeCCVAndExecutorHash

function _computeCCVAndExecutorHash(
  address[] memory ccvs,
  address executor
) internal pure returns (bytes32)

Computes a deterministic hash over CCV addresses and executor.

• Used to bind verifier configuration to the message.

_encodeTokenTransferV1

function _encodeTokenTransferV1(
  TokenTransferV1 memory tokenTransfer
) internal pure returns (bytes memory)

Encodes a token transfer.

_decodeTokenTransferV1

function _decodeTokenTransferV1(
  bytes calldata encoded,
  uint256 offset
) internal pure returns (
  TokenTransferV1 memory tokenTransfer,
  uint256 newOffset
)

Decodes a token transfer.

_encodeMessageV1

function _encodeMessageV1(
  MessageV1 memory message
) internal pure returns (bytes memory)

Encodes a CCIP message.

_decodeMessageV1

function _decodeMessageV1(
  bytes calldata encoded
) internal pure returns (MessageV1 memory message)

Decodes a CCIP message.

Constants

MAX_NUMBER_OF_TOKENS

uint256 public constant MAX_NUMBER_OF_TOKENS = 1;

MESSAGE_V1_REMOTE_CHAIN_ADDRESSES

uint256 public constant MESSAGE_V1_REMOTE_CHAIN_ADDRESSES = 2;

Structs

MessageV1

TokenTransferV1

Errors

• error InvalidDataLength(EncodingErrorLocation location)
• error InvalidEncodingVersion(uint8 version)

For a cross-contract error index, see Errors.

Notes

• Encoding and decoding functions must be strictly symmetric.
• Encoded messages must match the expected format exactly across chains.
• Message hashing depends on canonical encoding.
• Only a single token transfer is supported per message.
• Decoding will revert if message data is malformed or incomplete.

Usage context

Used by:

• OnRamp
• OffRamp
• TokenPool

Example:

bytes memory encoded = MessageV1Codec._encodeMessageV1(message);
bytes32 messageId = keccak256(encoded);

Related Interfaces & Contracts

• OnRamp
• OffRamp
• TokenPool
• ExtraArgsCodec
• CCVConfigValidation