# SecKeyCreateFromData(_:_:_:) Constructs a SecKeyRef object for a symmetric key. ``` func SecKeyCreateFromData(_ parameters: CFDictionary, _ keyData: CFData, _ error: UnsafeMutablePointer?>?) -> SecKey? ``` ## Parameters `parameters` A parameter dictionary that describes the key. See the discussion for details. `keyData` A `CFDataRef` object that contains the raw key data. `error` A pointer to a variable where an error object is stored upon failure. If not `NULL`, the caller is responsible for checking this variable and releasing the resulting object if it exists. ## Return Value A symmetric key. In Objective-C, call the function to free the key’s memory when you are done with it. ## Discussion The parameters dictionary must contain (at minimum) an entry for the [`kSecAttrKeyType`](/documentation/Security/kSecAttrKeyType) key with a value of [`kSecAttrKeyTypeAES`](/documentation/Security/kSecAttrKeyTypeAES) or any other key type defined in Key Type Value. The keys below may be optionally set in the parameters dictionary (with a `CFBooleanRef` value) to override the default key usage values: - [`kSecAttrCanEncrypt`](/documentation/Security/kSecAttrCanEncrypt) - [`kSecAttrCanDecrypt`](/documentation/Security/kSecAttrCanDecrypt) - [`kSecAttrCanWrap`](/documentation/Security/kSecAttrCanWrap) - [`kSecAttrCanUnwrap`](/documentation/Security/kSecAttrCanUnwrap) These values default to `true` if no value is specified. --- 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)