Hi, I'm running into an issue with App Attest in my iOS app, and I'm hoping you can help me troubleshoot. I've registered my app in App Check for both App Attest and Device Check, and I've double-checked that my bundle ID is correct. I've also enabled App Attest in Xcode capabilities and am testing on a physical device. However, when I run the app, I'm getting the following error in the console: Error getting App Check token; using placeholder token instead. Error: App attestation failed. HTTP status code: 403 "message": "App attestation failed." I've tried a few things, but I'm still stuck. Any suggestions on what might be causing this or how to resolve it would be greatly appreciated! Thanks in advance

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.

Hello Apple Team We are integrating App Attest with our backend and seeing a 400 Bad Request response when calling the attestation endpoint. The issue is that the response does not include an X-Request-ID or JSON error payload with id and code, which makes it hard to diagnose. Instead, it only returns a receipt blob. Request Details URL: https://data-development.appattest.apple.com/v1/attestationData Request Headers: Authorization: eyJraWQiOiI0RjVLSzRGV1JaIiwidHlwIjoiSldUIiwiYWxnIjoiRVMyNTYifQ.eyJpc3MiOiJOOVNVR1pNNjdRIiwiZXhwIjoxNzU3MDUxNTYwLCJpYXQiOjE3NTcwNDc5NjB9.MEQCIF236MqPCl6Vexg7RcPUMK8XQeACXogldnpuiNnGQnzgAiBQqASdbJ64g58xfWGpbzY3iohvxBSO5U5ZE3l87JjfmQ Content-Type: application/octet-stream Request Body: (Binary data, logged as [B@59fd7d35) Response Status: 400 Bad Request Response Headers: Date: Fri, 05 Sep 2025 04:52:40 GMT x-b3-traceid: 4c42e18094022424 x-b3-spanid: 4c42e18094022424 Response Body (truncated): "receipt": h'308006092A864886F70D01070... Problem The response does not include X-Request-ID. The response does not include JSON with id or code. Only a receipt blob is returned. Questions Can the x-b3-traceid be used by Apple to trace this failed request internally? Is it expected for some failures to return only a receipt blob without X-Request-ID? How should we interpret this error so we can handle it properly in production? Thanks in advance for your guidance.

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

Hey everyone, I'm hitting a really frustrating issue with App Attest. My app was working perfectly with DCAppAttestService on October 12th, but starting October 13th it started failing with DCError Code 2 "Failed to fetch App UUID" at DCAppAttestController.m:153. The weird part is I didn't change any code - same implementation, same device, same everything. I've tried switching between development and production entitlement modes, re-registered my device in the Developer Portal, created fresh provisioning profiles with App Attest capability, and verified that my App ID has App Attest enabled. DCAppAttestService.isSupported returns true, so the device supports it. Has anyone else run into this? This is blocking my production launch and I'm not sure if it's something on my end or an Apple infrastructure issue.

Hello everyone, I'm facing a critical, blocking issue where my developer account (Team ID: K655PX7A46) is unable to generate a valid provisioning profile with the App Attest entitlement. I have confirmed this is a server-side issue and am hoping to get visibility from an Apple engineer who can investigate. The Problem: When I generate a provisioning profile for an App ID with the "App Attest" capability enabled, the resulting profile is defective. It is missing the required com.apple.developer.app-attest.environment key in its entitlements dictionary, causing Xcode to fail the build. What I Have Proven: The issue is not a misconfiguration. The App Attest capability is correctly enabled and saved on the App ID configuration page. The issue is not isolated to one App ID. I created a brand new App ID from scratch, enabled the capability during creation, and the server still generates a defective profile with the same missing entitlement. I have definitive proof by inspecting the downloaded .mobileprovision file. The contents confirm the required key is missing. Steps to Reproduce on My Account: Create a new App ID on the Developer Portal. Enable the "App Attest" capability and save. Generate a new "iOS App Development" provisioning profile for this App ID. Download the profile and inspect its contents via security cms -D -i [profile]. Observe that the com.apple.developer.app-attest.environment key is missing. The Evidence (Contents of the Defective Profile): Here is the output from inspecting the profile for a brand new App ID (com.technology519.linksi.app2). As you can see, the correct entitlement is missing, and an incorrect devicecheck entitlement is present instead. This is a critical bug in the provisioning profile generation service for my account that is blocking all development. I have already filed a support ticket (Case #102721408444) but have so far only received generic, unhelpful responses. Can an Apple engineer please investigate this server-side issue with my account? Thank you.