---
title: Attestation Object Validation Guide
framework: DeviceCheck
role: article
role_heading: Article
path: devicecheck/attestation-object-validation-guide
---

# Attestation Object Validation Guide

Use this guide to validate your implementation of verifying the attestation object verification process.

## Example setup

Example setup Consider we have an example iOS Application with the following properties: appIDPrefix = "1234567890" (teamID) bundleID = "com.example.myapp" serverChallenge = "example_server_challenge" After calling generateKey(completionHandler:), this example produces the following keyId: "zgSY9YSD+7TaDXssY6WlOPVS1K3Lmk+pFhlcSWE+ZV0=" note: The keyId from the generateKey(completionHandler:) API is already in Base64 encoded format. After calling attestKey(_:clientDataHash:completionHandler:), this example produces the following attestationObject, as a Base64 encoded string: "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" You may use this guide as a reference to cross-check your attestation object validation operations against this sample attestation object, to ensure you are producing the correct results at each step, in your use case. Walking through the validation steps Verify that the x5c array contains the intermediate and leaf certificates for App Attest, starting from the credential certificate in the first data buffer in the array (credcert). Verify the validity of the certificates using Apple’s App Attest root certificate. Expected leaf certificate, as a Base64 encoded string: "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" Expected intermediate certificate, as a Base64 encoded string: "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" Create clientDataHash as the SHA256 hash of the one-time challenge your server sends to your app before performing the attestation, and append that hash to the end of the authenticator data (authData from the decoded object). Expected clientDataHash, as a Base64 encoded string: "9EZtaPketsEGIMt+Y8coMkRoXuHWRntUFg51MXIFfwNAAAAAAGFwcGF0dGVzdAAAAAAAAAAAIM4EmPWEg/u02g17LGOlpTj1UtSty5pPqRYZXElhPmVdpQECAyYgASFYIEMyVErPMj23dEQ8qvM59W5+lcck+sLBQlnzZeJEVlCyIlggtfsoW89Um8tgWUQS52gqJCfuran7Ut/tCxqxftCfqb2id2FwcGxlX2J1bmRsZV92ZXJzaW9uXzAxYTF4HGFwcGxlX3ZhbGlkYXRpb25fY2F0ZWdvcnlfMDFEAQAAAGV4YW1wbGVfc2VydmVyX2NoYWxsZW5nZQ==" Generate a new SHA256 hash of the composite item to create nonce. Expected nonce, as Base64 encoded string: "h7fQbZOkKU5G8BHma2zEAPC6sgcpl2xhlYC0KuYL/24=" Obtain the value of the credCert extension with OID 1.2.840.113635.100.8.2, which is a DER-encoded ASN.1 sequence. Decode the sequence and extract the single octet string that it contains. Verify that the string equals nonce. Expected octet string from credCert, as a Base64 encoded string: "h7fQbZOkKU5G8BHma2zEAPC6sgcpl2xhlYC0KuYL/24=" important: On macOS, obtain the value of the aclBlob for the key associated with the attestation with OID 1.2.840.113635.100.8.6, which is a DER-encoded ASN.1 sequence. Decode the sequence and extract the single octet string that it contains. Verify that the string equals MEAMAjExMDowCQwCb2uhAwEB/zAJDAJvYaEDAQH/MAsMBG9kZWyhAwEB/zAVDARvc2duoAYMBHJzZWMwBaYDAgEB. Expected octet string from aclBlob, as a Base64 encoded string: MEAMAjExMDowCQwCb2uhAwEB/zAJDAJvYaEDAQH/MAsMBG9kZWyhAwEB/zAVDARvc2duoAYMBHJzZWMwBaYDAgEB Create the SHA256 hash of the public key in credCert with X9.62 uncompressed point format, and verify that it matches the key identifier from your app. Expected public key SHA256 hash from credCert, as a Base64 encoded string: "inGjK2JbaAEhAsYwCns2zTyZDzsJ3OKx3Q2nnxk+mkY=" Compute the SHA256 hash of your app’s App ID, and verify that it’s the same as the authenticator data’s RP ID hash. Expected SHA256 hash of App ID, as a Base64 encoded string: "9EZtaPketsEGIMt+Y8coMkRoXuHWRntUFg51MXIFfwM=" Expected hash of RP_ID from the authenticator data field: "9EZtaPketsEGIMt+Y8coMkRoXuHWRntUFg51MXIFfwM=" Verify that the authenticator data’s counter field equals 0. Expected counter field: 0 note: The counter is incremented on each subsequent call to generateAssertion(_:clientDataHash:completionHandler:), following the call to attestKey(_:clientDataHash:completionHandler:). Verify that the authenticator data’s aaguid field is either appattestdevelop if operating in the development environment, or appattest followed by seven 0x00 bytes if operating in the production environment. Expected aaguid field for production: "\x61\x70\x70\x61\x74\x74\x65\x73\x74\x00\x00\x00\x00\x00\x00\x00" Verify that the authenticator data’s credentialId field is the same as the key identifier. Expected credentialId: "zgSY9YSD+7TaDXssY6WlOPVS1K3Lmk+pFhlcSWE+ZV0=" Verify the apple_validation_category_01 value within the extensions CBOR dictionary in the authenticator data. Expected apple_validation_category_01 UInt32-value for OS distributed executable: 1 Verify the apple_bundle_version_01 value within the extensions CBOR dictionary in the authenticator data. Expected apple_bundle_version_01 String-value for distributed App with bundle version of “1.0”: "1.0"

## See Also

### App Attest

- [Establishing your app’s integrity](devicecheck/establishing-your-app-s-integrity.md)
- [Validating apps that connect to your server](devicecheck/validating-apps-that-connect-to-your-server.md)
- [Assessing fraud risk](devicecheck/assessing-fraud-risk.md)
- [Preparing to use the app attest service](devicecheck/preparing-to-use-the-app-attest-service.md)
- [DCAppAttestService](devicecheck/dcappattestservice.md)
- [App Attest Environment](bundleresources/entitlements/com.apple.developer.devicecheck.appattest-environment.md)