What is CCTP Express?

CCTP Express: An intent based cross-chain bridging system built upon CCTP

Introduction

The protocol name explained what it is - CCTP Express provides an express way to use CCTP.

CCTP Express is an intent-based USDC bridging system, which introduces a filler-pay-first mechanism to enable instant USDC bridging for end users. Before delving into the technical details, let's understand what CCTP is and why an express way is necessary.

What is CCTP?

Cross-Chain Transfer Protocol (CCTP) is a permissionless on-chain utility that facilitates USDC transfers securely between blockchains networks via native burning and minting. Circle, the issuer of USDC, created it to improve capital efficiency and minimize trust requirements when using USDC across blockchain networks. CCTP enables developers to build multi-chain applications that provide secure, 1:1 transfers of USDC across blockchains for their users.

How CCTP works?

1. USDC is burned on the source chain: Using an app, an user initiates a transfer of USDC from one blockchain to another, and specifies the recipient wallet address on the destination chain. The app facilitates a burn of the specified amount of USDC on the source chain.

2. A signed attestation is fetched from Circle: Circle observes and attests to the burn event on the source chain. The app requests the attestation from Circle, which provides authorization to mint the specified amount of USDC on the destination chain.

3. USDC is minted on the destination chain: The app uses the attestation to trigger the minting of USDC. The specified amount of USDC is minted on the destination chain and sent to the recipient wallet address.

Problem - Waiting time on CCTP

Before signing an attestation for a source chain event, Circle waits for a specified number of on-chain block confirmations to pass to determine finality. The following table displays the average time it takes for an attestation to become available after a source chain event, which includes the ~20 seconds it takes for the attestation service to observe and sign the source chain event.

Mainnet:

Apart from Avalanche, Noble, and Solana, it typically takes around 8-13 minutes to achieve finality before the Circle team can sign on attestation for a source chain event. Despite this is quicker than using canonical bridges, the wait time remains a disadvantage for the DeFi market, which demands instant transaction processing.

Solution - CCTP Express

CCTP Express is positioned as a booster of CCTP - it provides a faster and cheaper way to bridge USDC using CCTP.

CCTP Express introduces an intent-based, filler pay first system building on top of CCTP. Instead of waiting for the 8 - 13 minutes, users would simply need to send the fund and receive the fund within 1 - 36 seconds. For users, CCTP Express is an instant and one click bridging process which is a better UX than the traditional CCTP route. Please see our architecture for more details.