module OffsitePayments::Integrations::Universal

def self.notification(post, options = {})
  Notification.new(post, options)
end

def self.return(query_string, options = {})
  Return.new(query_string, options)
end

def self.sign(fields, key)
  OpenSSL::HMAC.hexdigest(OpenSSL::Digest::SHA256.new, key, fields.sort.join)
end