Function

SecItemCopyMatching

Returns one or more keychain items that match a search query, or copies attributes of specific keychain items.

Declaration

OSStatus SecItemCopyMatching(CFDictionaryRef query, CFTypeRef  _Nullable *result);

Parameters

query

A dictionary that describes the search. A typical query dictionary consists of:

  • The item's class. Specify the kind of item you want, for example a password, a certificate, or a cryptographic key, using one of the class values in Item Class Keys and Values.

  • Attributes. Narrow the search by indicating the attributes that the found item or items should have. The more attributes you specify, the more refined the results, but not all attributes apply to all item classes. See Item Attribute Keys and Values for the complete list of possible attributes.

  • Search parameters. Condition the search in a variety of ways. For example, you can limit the results to a specific number of items, control case sensitivity when matching string attributes, or search only among a particular set of items. See Search Attribute Keys and Values for the complete list of possible search parameters.

  • One or more return types. Use the keys found in Item Return Result Keys to indicate whether you seek the item’s attributes, the item’s data, a reference to the data, a persistent reference to the data, or a combination of these. When you specify more than one return type, the search returns a dictionary containing each of the types you request. When your search allows multiple results, they’re all returned together in an array of items.

result

On return, a reference to the found items. The exact type of the result is based on the values supplied in attributes, as discussed in Item Return Result Keys.

Return Value

Discussion

By default, this function returns only the first match found. To obtain more than one matching item at a time, specify the search key kSecMatchLimit with a value greater than 1. The result will be an object of type CFArrayRef containing up to that number of matching items.

By default, this function searches for items in the keychain. To instead provide your own set of items to be filtered by this search query, specify the search key kSecMatchItemList and provide as its value a CFArrayRef object containing items of type SecKeychainItemRef, SecKeyRef, SecCertificateRef, or SecIdentityRef. The objects in the provided array must all be of the same type.

To limit a keychain search to a particular keychain or keychains, specify the search key kSecMatchSearchList and provide as its value a CFArrayRef object containing items of type SecKeychainRef items.

To convert from persistent item references to normal item references, specify the search key kSecMatchItemList with a value that consists of an object of type CFArrayRef referencing an array containing one or more elements of type CFDataRef (the persistent references), and a return-type key of kSecReturnRef whose value is kCFBooleanTrue. The objects in the provided array must all be of the same type.

When you use Xcode to create an application, Xcode adds an application-identifier entitlement to the application bundle. Keychain Services uses this entitlement to grant the application access to its own keychain items. You can also add a Keychain Access Groups Entitlement to the application, specifying an array of keychain access groups to which the application belongs. When you call the SecItemAdd function to add an item to the keychain, you can specify the access group to which that item should belong. By default, the SecItemCopyMatching function searches all the access groups to which the application belongs. However, you can add the kSecAttrAccessGroup key to the search dictionary to specify which access group to search for keychain items.

See Also

Keychain Item Search

Searching for Keychain Items

Find keychain items based on search criteria that you specify.

Item Return Result Keys

Specify how you want returned keychain item data formatted.