# open(_:) Decrypts a message, if the ciphertext is valid. ``` mutating func open(_ ciphertext: C) throws -> Data where C : DataProtocol ``` ## Parameters `ciphertext` The ciphertext message to decrypt. ## Return Value The resulting cleartext message if the message is authentic. ## Discussion You can call this method multiple times to decrypt a series of messages. When using this method, the recipient of the ciphertext messages needs to decrypt them in the same order that the sender encrypts them. > Note: The system throws errors from ``doc://com.apple.CryptoKit/documentation/CryptoKit/HPKE/Errors`` when it encounters them. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)