sinatra-digest-auth.rb

helpers do
    def protected!
        response = callcc do |cont|
            auth = Rack::Auth::Digest::MD5.new(cont, "Administrator only") do |username|
                "password" # username is ignored, or Password is always 'password' in this example.
            end

            auth.opaque = $$.to_s
            auth.call(request.env)
        end

        throw(:halt, response) if response.first == 401
    end
end

# Example:
#
# get '/admin/?' do
#     protected!
#     something to do...
# end
#