== .htdigest Auth Provider implementation

We provide an implementation of `link:../../jsdoc/module-vertx-auth-common-js_auth_provider-AuthProvider.html[AuthProvider]` which uses the .digest file format
to perform authentication. The provider will not watch for updates to the file after loading. If you need dynamic
user management it would be more convenient to use dynamic providers such as jdbc or mongo providers.

To use this project, add the following
dependency to the _dependencies_ section of your build descriptor:

* Maven (in your `pom.xml`):

[source,xml,subs="+attributes"]
----
<dependency>
 <groupId>io.vertx</groupId>
 <artifactId>vertx-auth-htdigest</artifactId>
 <version>3.8.2</version>
</dependency>
----

* Gradle (in your `build.gradle` file):

[source,groovy,subs="+attributes"]
----
compile 'io.vertx:vertx-auth-htdigest:3.8.2'
----

To create an instance you first need an .htdigest file. This file is created using the apache htdigest tool.

Once you've got one of these you can create a `link:../../jsdoc/module-vertx-auth-htdigest-js_htdigest_auth-HtdigestAuth.html[HtdigestAuth]` instance as follows:

[source,js]
----
var HtdigestAuth = require("vertx-auth-htdigest-js/htdigest_auth");
var authProvider = HtdigestAuth.create(vertx, ".htdigest");

----

Once you've got your instance you can authenticate with it just like any `link:../../jsdoc/module-vertx-auth-common-js_auth_provider-AuthProvider.html[AuthProvider]`.

The out of the box config assumes the usage of the file .htdigest in the root of the project.

== Authentication

When authenticating using this implementation, it assumes that the digest authorization header is parsed as a JSON
object which we refer from now on as authentication info:

[source,js]
----
var authInfo = {
  "username" : "Mufasa",
  "realm" : "testrealm@host.com",
  "nonce" : "dcd98b7102dd2f0e8b11d0f600bfb0c093",
  "method" : "GET",
  "uri" : "/dir/index.html",
  "response" : "6629fae49393a05397450978507c4ef1"
};

authProvider.authenticate(authInfo, function (res, res_err) {
  if (res_err == null) {
    var user = res;
  } else {
    // Failed!
  }
});

----

== Provider internal behavior

The provider will load the specified .htdigest file at start time and will not watch for modifications. If you
require dynamic reloads, you will need to restart the provider.

The implementation does not have any other state than the digest file itself, this means that validation and
generation of `nonce` strings and counters must be handled outside this provider.

Finally `auth-int` `qop` is not supported to avoid having to consume potential large blobs of data in order to
validate the hash of the full request. This is usually also not present on modern web browsers.

If validating if a user has a particular permission it will always return false since the htdigest file is a pure
authentication mechanism and not authorization.