How many keys can be stored in the iOS Secure Enclave?

Question

Is there a limit to the number of keys I can store in the iOS Secure Enclave?

I have read Apple's documentation about the Secure Enclave (with a lot of associated pages) and also Apple's document about security, but I haven't found anything about the Secure Enclave's capacity.

score 5 · Answer 1 · answered Mar 21 '19 at 14:08

5

I have tried to generate 1025 key pairs to try the Secure Enclave's capacity. Around number 400 I started to receive an error.

So I think, there s a limit. But right now I can not say if it is a size limit or quantity limit.

answered Mar 21 '19 at 14:08

Martin Žid

289
3
18

1

However I was more concerned that the limit will be 5 max. 10 keys (like with fingerprint you can use to authenticate). This test shows that it is much bigger number, which is enough for me right now. – Martin Žid Mar 21 '19 at 14:11

score -5 · Answer 2 · answered Mar 20 '19 at 13:17

According UserDefaults and other *.plist.

From iOS SDK codes, and related Apple official document..

 extension UserDefaults {


  /*!
   NSUserDefaultsSizeLimitExceededNotification is posted on the main queue when 
more data is stored in user defaults than is allowed. Currently there is no 
limit for local user defaults except on tvOS, where a warning notification will 
be posted at 512kB, and the process terminated at 1MB. For ubiquitous defaults, 
the limit depends on the logged in iCloud user.
 */
@available(iOS 9.3, *)
public class let sizeLimitExceededNotification: NSNotification.Name


// ....
}

Summary

Currently there is no limit for local user defaults
On tvOS, where a warning notification will be posted at 512kB, and the process terminated at 1MB.
For ubiquitous defaults, the limit depends on the logged in iCloud user.

How many keys can be stored in the iOS Secure Enclave?

2 Answers2