IMS LTI

LTI ruby implementation

Installation

Add this line to your application's Gemfile:

gem 'ims-lti'

And then execute:

$ bundle

Or install it yourself as:

$ gem install lti

Usage

LTI 1.x

Validating Launches

You can use the classes in the IMS::LTI::Models::Messages module to valdiate Launches

For example in a rails app you would do the following

authenticator = IMS::LTI::Services::MessageAuthenticator.new(request.url, request.request_parameters, shared_secret)

#Check if the signature is valid
return false unless authenticator.valid_signature?

# check if `params['oauth_nonce']` has already been used

#check if the message is too old
return false if DateTime.strptime(request.request_parameters['oauth_timestamp'],'%s') < 5.minutes.ago

params = { user_id: '123', lti_message_type: IMS::LTI::Models::Messages::BasicLTILaunchRequest::MESSAGE_TYPE }

header = SimpleOAuth::Header.new(:post, 'https://yoursite.com', params, consumer_key: oauth_consumer_key, consumer_secret: secret)

signed_params = header.signed_attributes.merge(params)

IMS::LTI::Services::MessageAuthenticator.new(launch_url, signed_params, secret)

Contributing

1. Fork it ( http://github.com/instructure/ims-lti/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 new Pull Request