Local Authentication

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Authenticate users biometrically or with a passphrase using Local Authentication.

Posts under Local Authentication tag

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Biometrics prompt + private key access race condition on since iOS 26.1
We are using SecItemCopyMatching from LocalAuthentication to access the private key to sign a challenge in our native iOS app twice in a few seconds from user interactions. This was working as expected up until about a week ago where we started getting reports of it hanging on the biometrics screen (see screenshot below). From our investigation we've found the following: It impacts newer iPhones using iOS 26.1 and later. We have replicated on these devices: iPhone 17 Pro max iPhone 16 Pro iPhone 15 Pro max iPhone 15 Only reproducible if the app tries to access the private key twice in quick succession after granting access to face ID. Looks like a race condition between the biometrics permission prompt and Keychain private key access We were able to make it work by waiting 10 seconds between private key actions, but this is terrible UX. We tried adding adding retries over the span of 10 seconds which fixed it on some devices, but not all. We checked the release notes for iOS 26.1, but there is nothing related to this. Screenshot:
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evaluatedPolicyDomainState
Hi Apple Developers, I'm having a problem with evaluatedPolicyDomainState: on the same device, its value keeps changing and then switching back to the original. My current iOS version is 26.1. I upgraded my iOS from version 18.6.2 to 26.1. What could be the potential reasons for this issue? { NSError *error; BOOL success = YES; char *eds = nil; int edslen = 0; LAContext *context = [[LAContext alloc] init]; // test if we can evaluate the policy, this test will tell us if Touch ID is available and enrolled // success = [context canEvaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]; if (SystemVersion > 9.3) { // test if we can evaluate the policy, this test will tell us if Touch ID is available and enrolled success = [context canEvaluatePolicy: LAPolicyDeviceOwnerAuthentication error:&error]; } else{ // test if we can evaluate the policy, this test will tell us if Touch ID is available and enrolled success = [context canEvaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]; } if (success) { if (@available(iOS 18.0, *)) { NSData *stateHash = nil; if ([context respondsToSelector:@selector(domainState)]) { stateHash = [[context performSelector:@selector(domainState)] performSelector:@selector(stateHash)]; }else{ stateHash = [context evaluatedPolicyDomainState]; } eds = (char *)stateHash.bytes; edslen = (int)stateHash.length; } else { eds = (char *)[[context evaluatedPolicyDomainState] bytes]; edslen = (int)[[context evaluatedPolicyDomainState] length]; } CC_SHA256(eds, edslen, uviOut); *poutlen = CC_SHA256_DIGEST_LENGTH; } else { *poutlen = 32; gm_memset(uviOut, 0x01, 32); } }
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LAContext.evaluatedPolicyDomainState change between major OS versions
The header documentation for the (deprecated) LAContext.evaluatedPolicyDomainState property contains the following: @warning Please note that the value returned by this property can change exceptionally between major OS versions even if the state of biometry has not changed. I noticed that the documentation for the new LAContext.domainState property does not contain a similar warning. I also found this related thread from 2016/17. Is the domainState property not susceptible to changes between major OS versions? Or is this generally not an issue anymore?
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448
Oct ’25
deviceOwnerAuthenticationWithCompanion evaluation not working as expected
In one of my apps I would like to find out if users have their device set up to authenticate with their Apple Watch. According to the documentation (https://developer.apple.com/documentation/localauthentication/lapolicy/deviceownerauthenticationwithcompanion) this would be done by evaluating the LAPolicy like this: var error: NSError? var canEvaluateCompanion = false if #available(iOS 18.0, *) { canEvaluateCompanion = context.canEvaluatePolicy(.deviceOwnerAuthenticationWithCompanion, error: &error) } But when I run this on my iPhone 16 Pro (iOS 18.5) with a paired Apple Watch SE 2nd Gen (watchOS 11.5) it always returns false and the error is -1000 "No companion device available". But authentication with my watch is definitely enabled, because I regularly unlock my phone with the watch. Other evaluations of using biometrics just works as expected. Anything that I am missing?
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Jul ’25
Permission requirements for LAContext's canEvaluatePolicy
Hi, I am developing an app that checks if biometric authentication capabilities (Face ID and Touch ID) are available on a device. I have a few questions: Do I need to include a privacy string in my app to use the LAContext's canEvaluatePolicy function? This function checks if biometric authentication is available on the device, but does not actually trigger the authentication. From my testing, it seems like a privacy declaration is only required when using LAContext's evaluatePolicy function, which would trigger the biometric authentication. Can you confirm if this is the expected behavior across all iOS versions and iPhone models? When exactly does the biometric authentication permission pop-up appear for users - is it when calling canEvaluatePolicy or evaluatePolicy? I want to ensure my users have a seamless experience. Please let me know if you have any insights on these questions. I want to make sure I'm handling the biometric authentication functionality correctly in my app. Thank you!
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Jun ’25
Face ID authentication via LAContext may not always result in App lifecycle notifications
When a user swipes up to see the app switcher, I put a blocking view over my app so the data inside cannot be seen if you flick through the app switcher. I do this by receive notifications(UIApplicationDidBecomeActiveNotification, UIApplicationWillResignActiveNotification) But on my iPhone 16 Pro, iOS 18.4.1 test device, Face ID authentication via LAContext may not always result in App lifecycle notifications.This caused my blocking view not to be removed. any ideas about the notification changes caused by Biometric authentication?
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Jun ’25
Unexpectedly invalidated Biometrics in iOS 18.3.2 or later
There is a sudden surge of users in our apps with invalidated biometrics. Even though the issue is being handled correctly and the user has another way to login, some of the users forgot their passwords and they can not login. Is there any known issue with Biometrics in iOS 18.3.2 or later? There is a (possible) related discussion here: https://discussions.apple.com/thread/256011565
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Apr ’25
How to Restrict Passkey Authentication to FaceID or TouchID Only
Hi everyone, I'm looking for a way to configure Passkey on iOS so that authentication is only possible using FaceID or TouchID. Specifically, I want to disable the use of passcodes and QR codes for authentication. Additionally, is there a method to detect if the authentication was done using a passcode or QR code? Thanks for your help!
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Apr ’25
iOS app build error with iOS 18 SDK and Xcode 16
Hi, I am able to build my iOS app successfully, developed in objective-C with iOS 17.5 SDK and Xcode 15. Due to requirement of Appstore we are trying to build with iOS 18 SDK and Xcode 16. When building getting error in LAEnvironmentState.h file: a) "Property requires field to be named" b) "Expected member name or ';' after declaration specifiers" Same app when opening with Xcode 15 gets build without any issue. Any help/suggestion would be appreciated.
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156
Apr ’25
Different PRF output when using platform or cross-platform authentication attachement
Hello, I am using the prf extension for passkeys that is available since ios 18 and macos15. I am using a fixed, hardcoded prf input when creating or geting the credentials. After creating a passkey, i try to get the credentials and retrieve the prf output, which works great, but i am getting different prf outputs for the same credential and same prf input used in the following scenarios: Logging in directly (platform authenticator) on my macbook/iphone/ipad i get "prf output X" consistently for the 3 devices When i use my iphone/ipad to scan the qr code on my macbook (cross-platform authenticator) i get "prf output Y" consistently with both my ipad and iphone. Is this intended? Is there a way to get deterministic prf output for both platform and cross-platform auth attachements while using the same credential and prf input?
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Apr ’25
LocalAuthentication (Alternative) in Autofill Credential Provider extension
Hi, how can you authenticate a User through Biometrics with iPhone Passcode as Fallback in the Autofill Credential Provider Extension? In the App it works without a problem. In the Extension I get "Caller is not running foreground" Yeah, it isn't, as it's just a sheet above e.g. Safari. I'd like to avoid having the user setup a Passcode dedicated to my App, especially because FaceID is way faster. Does anybody know how to achieve iOS native Auth in the extension? Please let me know, a code sample would be appreciated. Regards, Mia
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Mar ’25
MacOS sometimes not asking for password after sleep when close lid
Sometimes, when I close the lid using the MacOs version Sequoia 15.2, with the configuration to require a password for 5 seconds, the system does not ask for the password as expected. This happens sometimes even though nothing preventing the system from sleeping when you close and open the lid, but it still seems like a security concern. Is there some known issue related to this problem or a way to avoid it? Result of command pmset -g: Configuration:
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419
Feb ’25
Local Authentication & localized reason string
In a project I was using Local Authentication to authenticate a user. When I got a request to support smartcard/PIV token authentication (which Local Authentication does not support), I had to switch to Authorization Services, which works pretty. There's only one issue I have. Local Authentication's evaluatePolicy:localizedReason:reply: requires a reason in the form "<appname>" is trying to <localized reason>. The app is currently translated into 41 languages and I would like to use the localized strings for the AuthorizationEnvironment of Authorization Services as well. The problem is that Local Authentication prefixes the localized string with something like "<appname>" is trying to and Authorization Services does not do this. Is there a way to get this prefix from somewhere so I can manually add it to the (partially) localized string? Any help would be highly appreciated. Thank you, Marc
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Feb ’25