> For the complete documentation index, see [llms.txt](https://docs.arcan.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.arcan.finance/protocol/keys.md). # Opening a handle Computation never needs the plaintext. Opening does. Arcan keeps those steps apart. ## Who can ask The access list is the authority. A user decrypt succeeds only when that user and the contract both have persistent permission on the handle. A public decrypt succeeds only when the contract called `FHE.makePubliclyDecryptable`. A denied account cannot open a handle even if an older grant exists. ## What the key service returns The service decrypts the ciphertext for that request and returns the clear value to the requester. For a user decrypt, the requester is the allowed account, through the SDK. For a public decrypt, the cleartext may also be submitted on-chain with a proof. The contract checks the proof with `FHE.checkSignatures` before it trusts the number. The service does not choose the business rule. The contract already did, inside `add`, `sub`, and `select`. ## What never happens * The host does not decrypt in order to execute the transfer. * A node does not learn a balance because it stored the handle. * An account off the list does not receive the cleartext because it can see the ciphertext bytes. Delegation lets a contract lend its decrypt right to another account until an expiry. Revocation removes it. See the [access list](/solidity/acl.md) for the calls. --- # 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 dynamically by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.arcan.finance/protocol/keys.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 `build a script that syncs our docs to a CMS` 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.