GrapeAPISignature

GrapeAPISignature provides a AWS 4 style Authentication middleware to be used with grape. It calculates the 'AWS4-HMAC-SHA256' style signature and compares it against the HTTP_AUTHORIZATION header within the request.

Installation

Add this line to your application's Gemfile:

gem 'grape_api_signature'

And then execute:

$ bundle

Or install it yourself as:

$ gem install grape_api_signature

Usage

In your API

Example usage:

 
  class YourAPI < Grape::API
    Grape::Middleware::Auth::Strategies.add(:aws4_auth,
                                            GrapeAPISignature::Middleware::GrapeAuth,
                                            ->(options) { [options[:max_request_age] || 900, options[:user_setter]] })
     
    GrapeAPISignature::Middleware::GrapeAuth.default_authenticator do |_access_key, _region, _service|
     user = ... # find the user, this block is executed in the context of your Endpoint
     { user: user, secret_key: user.key }
    end
    
    helpers do
      attr_accessor :current_user
    end
    
    auth :aws4_auth,
        max_request_age: 100,
        user_setter: :'current_user=',
        &GrapeAPISignature::Middleware::GrapeAuth.default_authenticator
    
    get '/aws4_authorized' do
     'DONE'
    end
  end
  

Options:

• max_request_age => Time in seconds how long a request is valid
• user_setter => When provided this is be used to set the user on your Endtpoint instance if the validations was successful

If the validation was successful env['REMOTE_USER'] is set to the access_key.

If the validation was not successful HTTP-Status 401 is set via Grape#error! when the signature was wrong and 400 if Scheme does not match 'AWS4-HMAC-SHA256'

In your rspecs

The following code only supports 'application/json' as Content-Type.

# spec_helper.rb

require 'grape_api_signature/rspec'

# in your spec

describe 'your wishes' do
  include GrapeAPISignature::RSpec
  
  let(:secret_key) { 'SUPERSUPERSUPERSECRET' }
  let(:access_key) { 'MyUser' }
  
  
  # if you don't use Rails
  let(:hostname) { Rack::Test::DEFAULT_HOST }
  let(:port) { 80 }
  let(:host) { "#{hostname}:#{port}" }
  
  def https?
    port == 443
  end
  
  it 'should do' do
     get_with_auth '/'
  end
  
  it 'should also do' do
    post_with_auth '/', request_params
  end
  
end

In your Rails-App

This gem provides a coffee script to authenticate swagger demo requests via AWS 4.

# application.js.coffee

#= require aws-signature

# your swagger index.html, or what you use

<div id="header">
  <div class="swagger-ui-wrap">
    <form id="api_selector">
      <div class="input">
        <input type="text" placeholder="Username" id="input_apiUser" name="user">
      </div>
      <div class="input">
        <input type="password" placeholder="Password" id="input_apiPassword" name="password">
      </div>
    </form>
   </div>
</div>

Standalone RackMiddleware

Example usage:

...

max_request_age = 200

use GrapeAPISignature::Middleware::Auth, max_request_age  do |_access_key, _region, _service|
  user = ... 
  user.secret_key # different return value as for grape API's return only the key
end

run app

...

Standalone Authenticator/Signer

Example usage:

# Gemfile
gem 'grape_api_signature', require: 'grape_api_signature/signer_components'

# In your ruby file validate a request

auth = Authorization.new(request_method,
                         headers,
                         URI(url),
                         body,
                         max_request_age)
                         
auth.authentic?(secret_key)

# OR use the signer

signer = GrapeAPISignature::AWSSigner.new(
          access_key: user_id,
          secret_key: secret_key,
          region: authorization.region
)

signer.signature_only(request_method, uri, headers_to_sign, body)

# OR

signer.sign(request_method, uri, headers_to_sign, body)

Contributing

1. Fork it ( https://github.com/faber-lotto/grape_api_signature/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request