What is Cross-Chain Transfer Protocol (CCTP)?

CCTP is a permissionless on-chain utility that enables the flow of USDC across chains through native burning and minting. With CCTP, USDC is effectively teleported from one blockchain to another.

Why was CCTP important for Circle to create?

CCTP eliminates the need to use a conventional “lock-and-mint” bridge, which otherwise would lock native USDC on the source chain – incurring a security risk – and then mint a bridged version of USDC on the destination chain, which results in fragmentation of liquidity and poor UX.

Who was CCTP designed for?

CCTP serves as permissionless infrastructure for third-party developers to build on top of or integrate into their existing apps/dApps, wallets, and bridges.

Does Circle require KYC to use CCTP?

No. CCTP is a permissionless on-chain utility that is intended to be accessible through third-party developer products and services.

When will CCTP be available?

Developers can access our GitHub repo and developer guides today to begin building on CCTP on testnet for Ethereum and Avalanche. CCTP is expected to be live on mainnet for Ethereum and Avalanche in Mid-Q1 2023. CTTP is expected to expand to Solana and additional chains in H1 2023.

Can’t I use a Circle Account or Core API to move USDC across chains? What about a centralized exchange?

Yes, Circle Account and Core API are capable of moving USDC natively across chains. Those are Circle commercial products that a business entity can sign up for, in which they are KYC’d and undergo a compliance check.

While a centralized exchange cannot burn-and-mint USDC, it can effectively move USDC across blockchains because the exchange holds large amounts of liquidity on-platform for various forms of native USDC. A KYC’d user can deposit USDC from one blockchain into a centralized exchange, and then withdraw USDC on another blockchain to their external wallet.

In contrast to the above solutions, CCTP is permissionless, which means it is accessible to anyone and does not require signing up for an account. Users can move USDC through a CCTP-enabled app/dApp to any supported blockchain at any time. Additionally, developers can compose new on-chain experiences on top of CCTP within their apps/dApps.

How is CCTP different from cross-chain liquidity pool solutions?

In contrast to cross-chain liquidity pool solutions, CCTP is more capital efficient due to avoiding tying up liquidity in pools, and does not require additional fees to incentivize liquidity providers.

How does the USDC that is burned on the source chain end up being successfully minted on the destination chain?

All burns of USDC emit an event on the source chain, and it is the responsibility of the third-party app/dApp to trigger the minting of USDC on the destination chain. The mint is not automatically triggered by Circle. The mint requires a signed attestation from Circle's attestation service, which the third-party app/dApp is responsible for fetching.

How does the USDC that is burned on the source chain end up being successfully minted on the destination chain?

All burns of USDC emit an event on the source chain, and it is the responsibility of the third-party app/dApp to trigger the minting of USDC on the destination chain. The mint is not automatically triggered by Circle. The mint requires a signed attestation from Circle's attestation service, which the third-party app/dApp is responsible for fetching. Circle’s attestation service is permissionless and hosted by Circle, and while its unavailability would preclude mints from triggering, we anticipate extremely robust uptime and availability, similar to how our existing minting and redemption services operate today.

What happens if Circle’s attestation service is unresponsive?

Circle’s attestation service is permissionless and hosted by Circle, and while its unavailability would temporarily preclude new burn messages from being signed, we anticipate robust uptime and availability, similar to how our existing minting and redemption services operate today.q

Does Circle have access to or store any personally identifiable information (PII) when I send my USDC through CCTP?

No.

How does CCTP affect existing bridged versions of USDC?

CCTP does not directly affect existing bridged versions of USDC.

How does CCTP affect Circle’s plans to launch USDC on more blockchains?

Circle’s plans to bring USDC natively to more blockchain ecosystems remains the same. We envision CCTP to serve as a seamless connection where developers and users can easily move USDC natively across supported chains.


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