I'm currently reviewing the various DCError cases defined in Apple’s DeviceCheck framework (reference: https://aninterestingwebsite.com/documentation/devicecheck/dcerror-swift.struct). To better understand how to handle these in production, I’m looking for a clear breakdown of: Which specific DCError values can occur during service.generateKey, service.attestKey, and service.generateAssertion The realworld scenarios or conditions that typically cause each error for each method. If anyone has insight on how these errors arise and what conditions trigger them, I’d appreciate your input.

When presenting a cookie banner for GDPR purposes, should ATT precede the cookie banner? It seems that showing a Cookie Banner and then showing the ATT permission prompt afterwards (if a user elects to allow cookies/tracking) would be more appropriate. Related question: Should the “Allow Tracking” toggle for an app in system settings serve as a master switch for any granular tracking that might be managed by a 3rd party Consent Management Platform? If ATT is intended to serve as a master switch for tracking consent, if the ATT prompt is presented before a cookie banner, should the banner even appear if a user declines tracking consent? I’m not finding any good resources that describe this flow in detail and I’m seeing implementations all over the place on this. Help! Thanks!!!

I have an Autofill Passkey Provider working for Safari and Chrome via WebAuthn protocol. Unfortunately, Chrome will not offer my extension as a logon credential provider unless I add the credential to the ASCredentialIdentityStore. I wonder what is the best way to access the ASCredentialIdentityStore from an AutoFill extension? I understand I cannot access it directly from the extension context, so what is the best way to trigger my container app to run, based on a new WebAuthn registration? The best I can think of so far is for the www site to provide an App Link to launch my container app as part of the registration ceremony. Safari will offer my extension even without adding it to the ASCredentialIdentityStore, so I guess I should file a request with Chrome to work this way too, given difficulty of syncing ASCredentialIdentityStore with WebAuthn registration.

% curl -v https://app-site-association.cdn-apple.com/a/v1/zfcs.bankts.cn Host app-site-association.cdn-apple.com:443 was resolved. IPv6: (none) IPv4: 218.92.226.151, 119.101.148.193, 218.92.226.6, 115.152.217.3 Trying 218.92.226.151:443... Connected to app-site-association.cdn-apple.com (218.92.226.151) port 443 ALPN: curl offers h2,http/1.1 (304) (OUT), TLS handshake, Client hello (1): CAfile: /etc/ssl/cert.pem CApath: none (304) (IN), TLS handshake, Server hello (2): (304) (IN), TLS handshake, Unknown (8): (304) (IN), TLS handshake, Certificate (11): (304) (IN), TLS handshake, CERT verify (15): (304) (IN), TLS handshake, Finished (20): (304) (OUT), TLS handshake, Finished (20): SSL connection using TLSv1.3 / AEAD-AES256-GCM-SHA384 / [blank] / UNDEF ALPN: server accepted http/1.1 Server certificate: subject: C=US; ST=California; O=Apple Inc.; CN=app-site-association.cdn-apple.com start date: Sep 25 13:58:08 2025 GMT expire date: Mar 31 17:44:25 2026 GMT subjectAltName: host "app-site-association.cdn-apple.com" matched cert's "app-site-association.cdn-apple.com" issuer: CN=Apple Public Server RSA CA 11 - G1; O=Apple Inc.; ST=California; C=US SSL certificate verify ok. using HTTP/1.x GET /a/v1/zfcs.bankts.cn HTTP/1.1 Host: app-site-association.cdn-apple.com User-Agent: curl/8.7.1 Accept: / Request completely sent off < HTTP/1.1 404 Not Found < Content-Type: text/plain; charset=utf-8 < Content-Length: 10 < Connection: keep-alive < Server: nginx < Date: Wed, 04 Feb 2026 02:26:00 GMT < Expires: Wed, 04 Feb 2026 02:26:10 GMT < Age: 24 < Apple-Failure-Details: {"cause":"context deadline exceeded (Client.Timeout exceeded while awaiting headers)"} < Apple-Failure-Reason: SWCERR00301 Timeout < Apple-From: https://zfcs.bankts.cn/.well-known/apple-app-site-association < Apple-Try-Direct: true < Vary: Accept-Encoding < Via: https/1.1 jptyo12-3p-pst-003.ts.apple.com (acdn/3.16363), http/1.1 jptyo12-3p-pac-043.ts.apple.com (acdn/3.16363), https/1.1 jptyo12-3p-pfe-002.ts.apple.com (acdn/3.16363) < X-Cache: MISS KS-CLOUD < CDNUUID: 736dc646-57fb-43c9-aa0d-eedad3a534f8-1154605242 < x-link-via: yancmp83:443;xmmp02:443;fzct321:443; < x-b2f-cs-cache: no-cache < X-Cache-Status: MISS from KS-CLOUD-FZ-CT-321-35 < X-Cache-Status: MISS from KS-CLOUD-XM-MP-02-16 < X-Cache-Status: MISS from KS-CLOUD-YANC-MP-83-15 < X-KSC-Request-ID: c4a640c815640ee93c263a357ee919d6 < CDN-Server: KSFTF < X-Cdn-Request-ID: c4a640c815640ee93c263a357ee919d6 < Not Found Connection #0 to host app-site-association.cdn-apple.com left intact

Greetings, We are struggling to implement device binding according to your documentation. We are generation a nonce value in backend like this: public static String generateNonce(int byteLength) { byte[] randomBytes = new byte[byteLength]; new SecureRandom().nextBytes(randomBytes); return Base64.getUrlEncoder().withoutPadding().encodeToString(randomBytes); } And our mobile client implement the attestation flow like this: @implementation AppAttestModule - (NSData *)sha256FromString:(NSString *)input { const char *str = [input UTF8String]; unsigned char result[CC_SHA256_DIGEST_LENGTH]; CC_SHA256(str, (CC_LONG)strlen(str), result); return [NSData dataWithBytes:result length:CC_SHA256_DIGEST_LENGTH]; } RCT_EXPORT_MODULE(); RCT_EXPORT_METHOD(generateAttestation:(NSString *)nonce resolver:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject) { if (@available(iOS 14.0, *)) { DCAppAttestService *service = [DCAppAttestService sharedService]; if (![service isSupported]) { reject(@"not_supported", @"App Attest is not supported on this device.", nil); return; } NSData *nonceData = [self sha256FromString:nonce]; NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; NSString *savedKeyId = [defaults stringForKey:@"AppAttestKeyId"]; NSString *savedAttestation = [defaults stringForKey:@"AppAttestAttestationData"]; void (^resolveWithValues)(NSString *keyId, NSData *assertion, NSString *attestationB64) = ^(NSString *keyId, NSData *assertion, NSString *attestationB64) { NSString *assertionB64 = [assertion base64EncodedStringWithOptions:0]; resolve(@{ @"nonce": nonce, @"signature": assertionB64, @"deviceType": @"IOS", @"attestationData": attestationB64 ?: @"", @"keyId": keyId }); }; void (^handleAssertion)(NSString *keyId, NSString *attestationB64) = ^(NSString *keyId, NSString *attestationB64) { [service generateAssertion:keyId clientDataHash:nonceData completionHandler:^(NSData *assertion, NSError *assertError) { if (!assertion) { reject(@"assertion_error", @"Failed to generate assertion", assertError); return; } resolveWithValues(keyId, assertion, attestationB64); }]; }; if (savedKeyId && savedAttestation) { handleAssertion(savedKeyId, savedAttestation); } else { [service generateKeyWithCompletionHandler:^(NSString *keyId, NSError *keyError) { if (!keyId) { reject(@"keygen_error", @"Failed to generate key", keyError); return; } [service attestKey:keyId clientDataHash:nonceData completionHandler:^(NSData *attestation, NSError *attestError) { if (!attestation) { reject(@"attestation_error", @"Failed to generate attestation", attestError); return; } NSString *attestationB64 = [attestation base64EncodedStringWithOptions:0]; [defaults setObject:keyId forKey:@"AppAttestKeyId"]; [defaults setObject:attestationB64 forKey:@"AppAttestAttestationData"]; [defaults synchronize]; handleAssertion(keyId, attestationB64); }]; }]; } } else { reject(@"ios_version", @"App Attest requires iOS 14+", nil); } } @end For validation we are extracting the nonce from the certificate like this: private static byte[] extractNonceFromAttestationCert(X509Certificate certificate) throws IOException { byte[] extensionValue = certificate.getExtensionValue("1.2.840.113635.100.8.2"); if (Objects.isNull(extensionValue)) { throw new IllegalArgumentException("Apple App Attest nonce extension not found in certificate."); } ASN1Primitive extensionPrimitive = ASN1Primitive.fromByteArray(extensionValue); ASN1OctetString outerOctet = ASN1OctetString.getInstance(extensionPrimitive); ASN1Sequence sequence = (ASN1Sequence) ASN1Primitive.fromByteArray(outerOctet.getOctets()); ASN1TaggedObject taggedObject = (ASN1TaggedObject) sequence.getObjectAt(0); ASN1OctetString nonceOctet = ASN1OctetString.getInstance(taggedObject.getObject()); return nonceOctet.getOctets(); } And for the verification we are using this method: private OptionalMethodResult<Void> verifyNonce(X509Certificate certificate, String expectedNonce, byte[] authData) { byte[] expectedNonceHash; try { byte[] nonceBytes = MessageDigest.getInstance("SHA-256").digest(expectedNonce.getBytes()); byte[] combined = ByteBuffer.allocate(authData.length + nonceBytes.length).put(authData).put(nonceBytes).array(); expectedNonceHash = MessageDigest.getInstance("SHA-256").digest(combined); } catch (NoSuchAlgorithmException e) { log.error("Error while validations iOS attestation: {}", e.getMessage(), e); return OptionalMethodResult.ofError(deviceBindError.getChallengeNotMatchedError()); } byte[] actualNonceFromCert; try { actualNonceFromCert = extractNonceFromAttestationCert(certificate); } catch (Exception e) { log.error("Error while extracting nonce from certificate: {}", e.getMessage(), e); return OptionalMethodResult.ofError(deviceBindError.getChallengeNotMatchedError()); } if (!Arrays.equals(expectedNonceHash, actualNonceFromCert)) { return OptionalMethodResult.ofError(deviceBindError.getChallengeNotMatchedError()); } return OptionalMethodResult.empty(); } But the values did not matched. What are we doing wrong here? Thanks.

override func prepareInterface(forPasskeyRegistration registrationRequest: any ASCredentialRequest) int this function how can i get the "challenge" from user agent, the params "challenge" need to be used in webauthn navigator.credentials.create

I'm trying to setup device attestation. I believe I have everything setup correctly but the final step of signature validation never succeeds. I've added validation on the client side for debugging and it doesn't validate using CryptoKit. After the assertion is created, I try to validate it: assertion = try await DCAppAttestService.shared.generateAssertion(keyId, clientDataHash: clientDataHash) await validateAssertionLocallyForDebugging(keyId: keyId, assertionObject: assertion, clientDataHash: clientDataHash) In the validateAssertionLocallyForDebugging method, I extract all the data from the CBOR assertionObject and then setup the parameters to validate the signature, using the key that was created from the original attestation flow, but it fails every time. I'm getting the public key from the server using a temporary debugging API. let publicKeyData = Data(base64Encoded: publicKeyB64)! let p256PublicKey = try P256.Signing.PublicKey(derRepresentation: publicKeyData) let ecdsaSignature = try P256.Signing.ECDSASignature(derRepresentation: signature) let digestToVerify = SHA256.hash(data: authenticatorData + clientDataHash) print(" - Recreated Digest to Verify: \(Data(digestToVerify).hexDescription)") if p256PublicKey.isValidSignature(ecdsaSignature, for: digestToVerify) { print("[DEBUG] SUCCESS: Local signature validation passed!") } else { print("[DEBUG] FAILED: Local signature validation failed.") } I have checked my .entitlements file and it is set to development. I have checked the keyId and verified the public key. I have verified the public key X,Y, the RP ID Hash, COSE data, and pretty much anything else I could think of. I've also tried using Gemini and Claude to debug this and that just sends me in circles of trying hashed, unhashed, and double hashed clientData. I'm doing this from Xcode on an M3 macbook air to an iPhone 16 Pro Max. Do you have any ideas on why the signature is not validating with everything else appears to be working? Thanks

this is my monitor image that shows DeviceCheck api responding very slowly.

Hey, there are plans to design a government app. When a citizen will login they will see their passport, driving license etc... What is the solution of avoiding mandatory in-app user data deletion?

Hi team, We are experiencing an issue where some users in China are unable to create passkeys due to authentication errors. This is the UI flows The method we use to prompt users is passkey creation. Technically, this is implemented using Apple’s AuthenticationServices framework. We create an instance of ASAuthorizationController and conform to ASAuthorizationControllerDelegate to handle the results of the authentication attempt. In failure cases, we receive ASAuthorizationError.failed (code 1004), along with some additional details describing the nature of the failure. However, we are currently unable to determine the exact root cause of this issue or how to resolve it. At this point, we can only make assumptions based on the limited error information provided. Our current hypothesis is that due to network restrictions, Apple may be unable to reach the .well-known endpoint where we host the associated domain file. Alternatively, even if the file is successfully loaded and cached to Apple’s CDN, the system in China may not be able to reach the CDN itself. We would greatly appreciate it if you could help us understand what might be causing this problem and guide us on how we can resolve it effectively. Thanks, Hung

We recently deployed Attestation on our application, and for a majority of the 40,000 users it works well. We have about six customers who are failing attestation. In digging through debug logs, we're seeing this error "iOS assertion verification failed. Unauthorized access attempted." We're assuming that the UUID is blocked somehow on Apple side but we're stumped as to why. We had a customer come in and we could look at the phone, and best we can tell it's just a generic phone with no jailbroken or any malicious apps. How can we determine if the UUID is blocked?

Trusted execution is a generic name for a Gatekeeper and other technologies that aim to protect users from malicious code. General: Forums topic: Code Signing Forums tag: Gatekeeper Developer > Signing Mac Software with Developer ID Apple Platform Security support document Safely open apps on your Mac support article Hardened Runtime document WWDC 2022 Session 10096 What’s new in privacy covers some important Gatekeeper changes in macOS 13 (starting at 04: 32), most notably app bundle protection WWDC 2023 Session 10053 What’s new in privacy covers an important change in macOS 14 (starting at 17:46), namely, app container protection WWDC 2024 Session 10123 What’s new in privacy covers an important change in macOS 15 (starting at 12:23), namely, app group container protection Updates to runtime protection in macOS Sequoia news post Testing a Notarised Product forums post Resolving Trusted Execution Problems forums post App Translocation Notes (aka Gatekeeper path randomisation) forums post Most trusted execution problems are caused by code signing or notarisation issues. See Code Signing Resources and Notarisation Resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

I need to launch ASWebAuthenticationSession from single sign on extension, but its not launching it might issue with anchoring window, I have create custom windo and passing it in presentanchor(for session) function, custom window is launching but ASWebAuthenticationSession browser is not launching Note - flow is like this Apple PSSO register window lauched OIDC login will happen via ASWebAuthenticationSession to get accesstoken which will use in device registration but ASWebAuthenticationSession is not launching, I am using custom scheme as redirect URI iskeywindow for custom window is always false what is right approach to achieve the goal

Hi, We're in the process of implementing Apple's App Integrity, but am getting stalled due to missing documents. Can anyone assist with this? We've been following https://aninterestingwebsite.com/documentation/devicecheck/validating-apps-that-connect-to-your-server to make the necessary updates, but have come up short with where the document references decoding the Attestation Object. Can we get more information here and how the decoding process work?

Hi, Xcode Instruments shows multiple Points of Interest with the information that the framework is not listed in my Privacy Manifest. However, I have already included them in the Privacy Manifest under the privacy tracking domains. I have this problem with every tracking domain i listed in the Privacy Manifest's Privacy Tracking Domains. Did I make a mistake in my Privacy Manifest declaration?

When developing and testing using my phone I got prompted for allowing app tracking. I later uploaded a build to TestFlight, deleted the old testing app and installed the TestFlight build. I am now stuck in an infinite loop of not getting prompted for allowing app tracking for the app. When entering the app settings the toggle for tracking never appears which leaves me not able to enter the app's content. My guess is that the prompt can only be shown once for the app bundle, but there has to be a way for me to get prompted again without changing the app bundle id. Help is appreciated since this app is scheduled to be published in a week.

Hi, we were recently approved for the com.apple.developer.web-browser.public-key-credential entitlement and have added it to our app. It initially worked as expected for a couple of days, but then it stopped working. We're now seeing the same error as before adding the entitlement: Told not to present authorization sheet: Error Domain=com.apple.AuthenticationServicesCore.AuthorizationError Code=1 "(null)" ASAuthorizationController credential request failed with error: Error Domain=com.apple.AuthenticationServices.AuthorizationError Code=1004 "(null)" Do you have any insights into what might be causing this issue? Thank you!

Dear Apple Developer Support Team, We are experiencing a recurring issue with the DeviceCheck API where the following error is being returned: com.apple.devicecheck.error 0 Upon analyzing our logs, we have noticed that this error occurs significantly more often when users are connected to Wi-Fi networks, compared to mobile networks. This leads us to suspect that there might be a relationship between Wi-Fi configuration and the DeviceCheck service’s ability to generate or validate tokens. We would like to know: Is this error code (0) known to be caused by specific types of network behavior or misconfigurations on Wi-Fi networks (e.g., DNS filtering, firewall restrictions, proxy servers)? Are there any recommended best practices for ensuring reliable DeviceCheck API communication over Wi-Fi networks? Additionally, could you please clarify what general conditions could trigger this com.apple.devicecheck.error 0? The lack of specific documentation makes debugging this issue difficult from our side. Any guidance or internal documentation on this error code and its potential causes would be greatly appreciated. IDE: Xcode 16.3 Looking forward to your support. Best regards,

I'm trying to use ASWebAuthenticationSession on macOS but there is a weird crash and I have no idea what to do. It looks like there is a main thread check in a framework code that I have no control over. Any help would be appreciated. Thank you in advance. The stack of crashed thread has no symbols, even for supposedly my code in OAuthClient.authenticate. macOS 15.4.1 (24E263) Xcode Version 16.3 (16E140) Thread 11: EXC_BREAKPOINT (code=1, subcode=0x10039bb04) Thread 12 Queue : com.apple.NSXPCConnection.m-user.com.apple.SafariLaunchAgent (serial) #0 0x0000000100b17b04 in _dispatch_assert_queue_fail () #1 0x0000000100b52834 in dispatch_assert_queue$V2.cold.1 () #2 0x0000000100b17a88 in dispatch_assert_queue () #3 0x000000027db5f3e8 in swift_task_isCurrentExecutorWithFlagsImpl () #4 0x00000001022c7754 in closure #1 in closure #1 in OAuthClient.authenticate() () #5 0x00000001022d0c98 in thunk for @escaping @callee_guaranteed (@in_guaranteed URL?, @guaranteed Error?) -&gt; () () #6 0x00000001c7215a34 in __102-[ASWebAuthenticationSession initWithURL:callback:usingEphemeralSession:jitEnabled:completionHandler:]_block_invoke () #7 0x00000001c72163d0 in -[ASWebAuthenticationSession _endSessionWithCallbackURL:error:] () #8 0x00000001c7215fc0 in __43-[ASWebAuthenticationSession _startDryRun:]_block_invoke_2 () #9 0x0000000194e315f4 in __invoking___ () #10 0x0000000194e31484 in -[NSInvocation invoke] () #11 0x00000001960fd644 in __NSXPCCONNECTION_IS_CALLING_OUT_TO_REPLY_BLOCK__ () #12 0x00000001960fbe40 in -[NSXPCConnection _decodeAndInvokeReplyBlockWithEvent:sequence:replyInfo:] () #13 0x00000001960fb798 in __88-[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:]_block_invoke_3 () #14 0x0000000194a6ef18 in _xpc_connection_reply_callout () #15 0x0000000194a6ee08 in _xpc_connection_call_reply_async () #16 0x0000000100b3130c in _dispatch_client_callout3_a () #17 0x0000000100b362f8 in _dispatch_mach_msg_async_reply_invoke () #18 0x0000000100b1d3a8 in _dispatch_lane_serial_drain () #19 0x0000000100b1e46c in _dispatch_lane_invoke () #20 0x0000000100b2bfbc in _dispatch_root_queue_drain_deferred_wlh () #21 0x0000000100b2b414 in _dispatch_workloop_worker_thread () #22 0x0000000100c0379c in _pthread_wqthread () My code: @MainActor func authenticate() async throws { let authURL = api.authorizationURL( scopes: scopes, state: state, redirectURI: redirectURI ) let authorizationCodeURL: URL = try await withUnsafeThrowingContinuation { c in let session = ASWebAuthenticationSession(url: authURL, callback: .customScheme(redirectScheme)) { url, error in guard let url = url else { c.resume(throwing: error ?? Error.unknownError("Failed to get authorization code")) return } c.resume(returning: url) } session.presentationContextProvider = presentationContextProvider session.start() } let authorizationCode = try codeFromAuthorizationURL(authorizationCodeURL) (storedAccessToken, storedRefreshToken) = try await getTokens(authorizationCode: authorizationCode) } Here is disassembly of the crashed function. libdispatch.dylib`_dispatch_assert_queue_fail: 0x10067fa8c &lt;+0&gt;: pacibsp 0x10067fa90 &lt;+4&gt;: sub sp, sp, #0x50 0x10067fa94 &lt;+8&gt;: stp x20, x19, [sp, #0x30] 0x10067fa98 &lt;+12&gt;: stp x29, x30, [sp, #0x40] 0x10067fa9c &lt;+16&gt;: add x29, sp, #0x40 0x10067faa0 &lt;+20&gt;: adrp x8, 71 0x10067faa4 &lt;+24&gt;: add x8, x8, #0x951 ; "not " 0x10067faa8 &lt;+28&gt;: adrp x9, 70 0x10067faac &lt;+32&gt;: add x9, x9, #0x16b ; "" 0x10067fab0 &lt;+36&gt;: stur xzr, [x29, #-0x18] 0x10067fab4 &lt;+40&gt;: cmp w1, #0x0 0x10067fab8 &lt;+44&gt;: csel x8, x9, x8, ne 0x10067fabc &lt;+48&gt;: ldr x10, [x0, #0x48] 0x10067fac0 &lt;+52&gt;: cmp x10, #0x0 0x10067fac4 &lt;+56&gt;: csel x9, x9, x10, eq 0x10067fac8 &lt;+60&gt;: stp x9, x0, [sp, #0x10] 0x10067facc &lt;+64&gt;: adrp x9, 71 0x10067fad0 &lt;+68&gt;: add x9, x9, #0x920 ; "BUG IN CLIENT OF LIBDISPATCH: Assertion failed: " 0x10067fad4 &lt;+72&gt;: stp x9, x8, [sp] 0x10067fad8 &lt;+76&gt;: adrp x1, 71 0x10067fadc &lt;+80&gt;: add x1, x1, #0x8eb ; "%sBlock was %sexpected to execute on queue [%s (%p)]" 0x10067fae0 &lt;+84&gt;: sub x0, x29, #0x18 0x10067fae4 &lt;+88&gt;: bl 0x1006c258c ; symbol stub for: asprintf 0x10067fae8 &lt;+92&gt;: ldur x19, [x29, #-0x18] 0x10067faec &lt;+96&gt;: str x19, [sp] 0x10067faf0 &lt;+100&gt;: adrp x0, 71 0x10067faf4 &lt;+104&gt;: add x0, x0, #0x956 ; "%s" 0x10067faf8 &lt;+108&gt;: bl 0x1006b7b64 ; _dispatch_log 0x10067fafc &lt;+112&gt;: adrp x8, 108 0x10067fb00 &lt;+116&gt;: str x19, [x8, #0x2a8] -&gt; 0x10067fb04 &lt;+120&gt;: brk #0x1

Hi Apple Team and Community, We encountered a sudden and widespread failure related to the App Attest service on Friday, July 25, starting at around 9:22 AM UTC. After an extended investigation, our network engineers noted that the size of the attestation objects received from the attestKey call grew in size notably starting at that time. As a result, our firewall began blocking the requests from our app made to our servers with the Base64-encoded attestation objects in the payload, as these requests began triggering our firewall's max request length rule. Could Apple engineers please confirm whether there was any change rolled out by Apple at or around that time that would cause the attestation object size to increase? Can anyone else confirm seeing this? Any insights from Apple or others would be appreciated to ensure continued stability. Thanks!