> For the complete documentation index, see [llms.txt](https://takes.gitbook.io/takes-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://takes.gitbook.io/takes-docs/security-and-trust/cross-chain-security.md). # Cross-chain security Tokens on Arc, Ethereum, Base, Arbitrum, and Monad use Circle CCTP to transfer USDC and authenticated messages to and from their HyperEVM hubs. New HyperEVM tokens use a dedicated local hub and do not need this transfer. The receiving contracts check the source network, paired sender, recipient, and request. The hub must receive at least the exact principal; excess reserve is segregated from user backing. Redemption return requires enough proceeds to have arrived. ## Finality and transfer routes Finality describes how firmly a transaction is recorded by its network. Circle signs a message after the route's required level is reached. Ethereum, Base and Arbitrum deposits can use Fast finality; Arc and Monad deposits and all returning USDC use Standard. Commands normally use Standard; an immutable switch can enable Fast commands on supported Ethereum, Base and Arbitrum testnet deployments only. Fast command effects during a source reorganization must not be assumed to have Circle USDC loss coverage. This switch cannot be enabled on mainnet. Receiving contracts enforce their configured finality, route, sender and recipient. Expired Fast transfers are re-attested with the same nonce, never reburned. Circle prevents reuse of the same message; request identity and execution-state checks prevent repeated settlement. These controls do not undo an action if its source block is later removed. That case can require operator recovery. These checks depend on Circle's contracts and signatures, both networks, and the HyperCore deposit path. A valid transfer can still wait for finality or delivery. HyperEVM tokens avoid Circle transfer risk for holder requests, but still depend on account deposits and withdrawals. See [Networks](/takes-docs/reference/supported-networks.md#networks), [Fees and limits](/takes-docs/reference/fees-and-limits.md#fees-and-limits), and [Circle's message-handling guide](https://developers.circle.com/cctp/references/technical-guide). There is no general timeout refund if a transfer stalls. See [Failure and recovery](/takes-docs/security-and-trust/failure-and-recovery.md#failure-and-recovery). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://takes.gitbook.io/takes-docs/security-and-trust/cross-chain-security.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.