SafetyNetAttestation

A Ruby gem to verify SafetyNet attestation statements from Google Play Services on your server.

This gem verifies that the statement:

• has a valid signature that is trusted using certificates from https://pki.goog/
• has the correct nonce
• has been generated recently (default allowed leeway from current time is 60 seconds)
• has a signing certificate with the correct subject

With a valid statement your application can then inspect the information contained about the device integrity, calling app, and if applicable any integrity errors and potential solutions (see usage).

Installation

Add this line to your application's Gemfile:

gem 'safety_net_attestation'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install safety_net_attestation

Usage

Request an attestation statement as described in the Android developer documentation and send the JWS response to your server application.

In your server application code, do the following:

require "safety_net_attestation"

statement = begin 
  SafetyNetAttestation::Statement.new(jws_response).verify(nonce)
rescue SafetyNetAttestation::Error => e
  # Statement is not valid, you should abort
end

statement.json
# => {"apkPackageName": "com.package.name.of.requesting.app", "ctsProfileMatch": true, ... }

# snake cased convenience methods are available after #verify call succeeded, use these to make your specific checks: 
statement.cts_profile_match?
# => true
statement.basic_integrity?
# => true
statement.apk_package_name
# => "com.package.name.of.requesting.app"
statement.apk_certificate_digest_sha256
# => ["..."]
statement.error
# => nil
statement.advice
# => nil

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bin/rspec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/bdewater/safety_net_attestation. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

The gem and its authors are unaffiliated with Google.