Android Key Attestation Sample

This sample illustrates how to use the Bouncy Castle ASN.1 parser to extract information from an Android attestation data structure to verify that a key pair has been generated in an Android device. This sample demonstrates how to verify a certificate on a server.

Introduction

This example demonstrates the following tasks:

Loading the certificates from PEM/DER-encoded strings.
Verifying the X.509 certificate chain, up to the root. This includes checking that the root certificate is one of Google's root certificates listed in https://developer.android.com/training/articles/security-key-attestation.
Extracting the attestation extension data from the attestation certificate.
Verifying (and printing) data elements from the attestation extension.

For more information about the process of extracting attestation certificate extension data, as well as the extension data schema, see the Key Attestation Android developer training article.

Note that this sample demonstrates the verification of a certificate on a server and not on the Android framework. Although you can test the certificate and extensions directly on a device, it is safer to run these checks on a separate server you can trust.

Pre-requisites

Up-to-date Java JDK
Bouncy Castle Cryptography Java APIs (included as dependency in gradle build configuration).

Getting Started

This sample uses the Gradle build system. To build this project, use the gradlew build command or use “Import Project” in IntelliJ or Android Studio.

Run the main method in KeyAttestationExample directly or use the gradlew run --args="<cert-directory>" task to execute this sample. The cert-directory must contain the certificate chain, one certificate per file in either DER or PEM encoding and the files are read in alphabetical order. For example the provided /examples/pem/algorithm_EC_SecurityLevel_StrongBox/ can be used.

Support

Stack Overflow: http://stackoverflow.com/questions/tagged/android

If you've found an error in this sample, please file an issue: https://github.com/googlesamples/android-key-attestation

Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.

License

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.