[Duo Security](https://duosecurity.com/) is a cloud second-factor
authentication service that supports a wide variety of different
mechanisms for a user to establish a second authentication factor.  It is
intended to supplement local authentication systems, such as
password-based authentication, with an unrelated second factor: possession
of a device, or access to a phone.  Duo Security provides direct
integration with a variety of applications and a self-service web sign-up
interface, but for more control, it also provides several RESTful APIs
that can perform all possible actions on Duo accounts, users, and their
devices.

This module implements a client for the Duo REST APIs.  It differs from
the sample Perl implementation provided by Duo in that it attempts to wrap
the Duo data model and JSON information in Perl objects and provide
logical and convenient methods on those objects to make writing Perl
clients of Duo simpler and easier.  It tries to abstract portions of the
API, such as the endpoint URLs, that allow for more natural and less
cluttered Perl code than manipulating the JSON data structures directly.

The API implementation is currently incomplete and contains just the calls
required by Stanford's integration.  Only the Auth and Admin APIs are
implemented, and both are partial.  However, the Net::Duo `call`,
`call_json`, and `call_json_paged` methods can be used to make calls to
APIs that aren't fully implemented.