Safire

Safire is a lean Ruby library that implements SMART on FHIR and UDAP client protocols for healthcare applications.

Features

SMART on FHIR App Launch (v2.2.0)

Discovery (/.well-known/smart-configuration)
Public Client (PKCE)
Confidential Symmetric Client (client_secret + HTTP Basic Auth)
Confidential Asymmetric Client (private_key_jwt with RS384/ES384)
POST-Based Authorization

UDAP

Planned. See ROADMAP.md for details.

Installation

Requires Ruby ≥ 4.0.2.

gem 'safire'

bundle install

Quick Start

require 'safire'

# Step 1 — Create a client (Hash config or Safire::ClientConfig.new)
client = Safire::Client.new(
  base_url:     'https://launch.smarthealthit.org/v/r4/sim/eyJoIjoiMSJ9/fhir',
  client_id:    'my_client_id',
  redirect_uri: 'https://myapp.example.com/callback',
  scopes:       ['openid', 'profile', 'patient/*.read']
)

# Step 2 — Discover SMART metadata (lazy — only called when needed)
metadata = client.server_metadata
puts metadata.authorization_endpoint
puts metadata.capabilities.join(', ')

# Step 3 — Build the authorization URL (Safire generates state + PKCE automatically)
auth_data = client.authorization_url
# auth_data => { auth_url:, state:, code_verifier: }
# Store state and code_verifier server-side, redirect the user to auth_data[:auth_url]

# Step 4 — Exchange the authorization code for tokens (on callback)
token_data = client.request_access_token(
  code:          params[:code],
  code_verifier: session[:code_verifier]
)
# token_data => { "access_token" => "...", "token_type" => "Bearer", ... }

# Step 5 — Refresh when the access token expires
new_tokens = client.refresh_token(refresh_token: token_data['refresh_token'])

Supported SMART Client Types

`client_type:`	Authentication	When to use
`:public` (default)	PKCE only	Browser/mobile apps that cannot store a secret
`:confidential_symmetric`	HTTP Basic Auth (`client_secret`)	Server-side apps with a securely stored secret
`:confidential_asymmetric`	JWT assertion (`private_key_jwt`, RS384/ES384)	Server-side apps using a registered key pair

For a confidential asymmetric client, provide a private key and key ID:

client = Safire::Client.new(
  {
    base_url:    'https://fhir.example.com',
    client_id:   'my_client_id',
    redirect_uri: 'https://myapp.example.com/callback',
    scopes:      ['openid', 'profile', 'patient/*.read'],
    private_key: OpenSSL::PKey::RSA.new(File.read('private_key.pem')),
    kid:         'my-key-id-123'
  },
  client_type: :confidential_asymmetric
)
# Authorization and token exchange are identical — Safire builds the JWT assertion automatically

Configuration

Safire.configure do |config|
  config.logger   = Rails.logger   # Default: $stdout
  config.log_http = true           # Log HTTP requests (sensitive headers always filtered)
end

See the Configuration Guide for all options including user_agent, log_level, and SSL settings.

Demo Application

A Sinatra-based demo is included in href="examples/sinatra_app/">:

bin/demo
# Visit http://localhost:4567

Demonstrates SMART discovery, all authorization flows, and token refresh. See href="examples/sinatra_app/README_md.html"> for details.

Development

bin/setup            # Install dependencies
bundle exec rspec    # Run tests
bin/console          # Interactive prompt

To serve the docs locally:

bin/docs
cd docs && bundle install && bundle exec jekyll serve
# Visit http://localhost:4000/safire/

Contributing

Bug reports and pull requests are welcome. Please read CONTRIBUTION.md before opening a PR — it covers branch naming, commit message style, and the sign-off requirement.

License

Available as open source under the Apache 2.0 License.

Parts of this project were developed with AI assistance (Claude Code) and reviewed by maintainers.