Argon2i Password Encoder

Add/modify sections for the Argon2i password encoder (symfony/symfony#21604).

Author: zanbaldwin

best_practices/security.rst

@@ -38,6 +38,13 @@ of ``bcrypt`` are the inclusion of a *salt* value to protect against rainbow
 table attacks, and its adaptive nature, which allows to make it slower to
 remain resistant to brute-force search attacks.
 
+.. note::
+
+    :ref:`Argon2i <reference-security-argon2i>` is the hashing algorithm as
+    recommended by industry standards, but this won't be available to you unless
+    you are using PHP 7.2+ or have the `libsodium`_ extension installed.
+    ``bcrypt`` is sufficient for most applications.
+
 With this in mind, here is the authentication setup from our application,
 which uses a login form to load users from the database:
 
@@ -397,3 +404,4 @@ Next: :doc:`/best_practices/web-assets`
 .. _`ParamConverter`: https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/converters.html
 .. _`@Security annotation`: https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/security.html
 .. _`FOSUserBundle`: https://github.com/FriendsOfSymfony/FOSUserBundle
+.. _`libsodium`: https://pecl.php.net/package/libsodium

doctrine/registration_form.rst

@@ -132,7 +132,7 @@ With some validation added, your class may look something like this::
 
         public function getSalt()
         {
-            // The bcrypt algorithm doesn't require a separate salt.
+            // The bcrypt and argon2i algorithms don't require a separate salt.
             // You *may* need a real salt if you choose a different encoder.
             return null;
         }

reference/configuration/security.rst

@@ -82,6 +82,10 @@ Each part will be explained in the next section.
                     algorithm:            plaintext
                     ignore_case:          false
 
+                # Argon2i encoder
+                Acme\DemoBundle\Entity\User6:
+                    algorithm:            argon2i
+
             providers:            # Required
                 # Examples:
                 my_in_memory_provider:
@@ -611,7 +615,7 @@ persisting the encoded password alone is enough.
 
 .. note::
 
-    All the encoded passwords are ``60`` characters long, so make sure to
+    BCrypt encoded passwords are ``60`` characters long, so make sure to
     allocate enough space for them to be persisted.
 
 .. tip::
@@ -622,6 +626,64 @@ persisting the encoded password alone is enough.
 
     .. _reference-security-firewall-context:
 
+.. _reference-security-argon2i:
+
+Using the Argon2i Password Encoder
+----------------------------------
+
+.. caution::
+
+    To use this encoder, you either need to use PHP version 7.2 or install
+    the `libsodium`_ extension.
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # app/config/security.yml
+        security:
+            # ...
+
+            encoders:
+                Symfony\Component\Security\Core\User\User:
+                    algorithm: argon2i
+
+    .. code-block:: xml
+
+        <!-- app/config/security.xml -->
+        <config>
+            <!-- ... -->
+            <encoder
+                class="Symfony\Component\Security\Core\User\User"
+                algorithm="argon2i"
+            />
+        </config>
+
+    .. code-block:: php
+
+        // app/config/security.php
+        use Symfony\Component\Security\Core\User\User;
+
+        $container->loadFromExtension('security', array(
+            // ...
+            'encoders' => array(
+                User::class => array(
+                    'algorithm' => 'argon2i',
+                ),
+            ),
+        ));
+
+A salt for each new password is generated automatically and need not be
+persisted. Since an encoded password contains the salt used to encode it,
+persisting the encoded password alone is enough.
+
+.. note::
+
+    Argon2i encoded passwords are ``96`` characters long, but due to the hashing
+    requirements saved in the resulting hash this may change in the future.
+
+.. _reference-security-firewall-context:
+
 Firewall Context
 ----------------
 
@@ -749,3 +811,4 @@ To use HTTP-Digest authentication you need to provide a realm and a secret:
 
 .. _`PBKDF2`: https://en.wikipedia.org/wiki/PBKDF2
 .. _`ircmaxell/password-compat`: https://packagist.org/packages/ircmaxell/password-compat
+.. _`libsodium`: https://pecl.php.net/package/libsodium

security.rst

@@ -457,8 +457,8 @@ C) Encoding the User's Password
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Whether your users are stored in ``security.yml``, in a database or somewhere
-else, you'll want to encode their passwords. The best algorithm to use is
-``bcrypt``:
+else, you'll want to encode their passwords. The most suitable algorithm to use
+is ``bcrypt``:
 
 .. configuration-block::
 
@@ -593,8 +593,8 @@ before inserting them into the database? Don't worry, see
 
     Supported algorithms for this method depend on your PHP version, but
     include the algorithms returned by the PHP function :phpfunction:`hash_algos`
-    as well as a few others (e.g. bcrypt). See the ``encoders`` key in the
-    :doc:`Security Reference Section </reference/configuration/security>`
+    as well as a few others (e.g. bcrypt and argon2i). See the ``encoders`` key
+    in the :doc:`Security Reference Section </reference/configuration/security>`
     for examples.
 
     It's also possible to use different hashing algorithms on a user-by-user

security/named_encoders.rst

@@ -101,6 +101,12 @@ named encoders:
             ),
         ));
 
+.. note::
+
+    If you are running PHP 7.2+ or have the `libsodium`_ extension installed,
+    then the recommended hashing algorithm to use is
+    :ref:`Argon2i <reference-security-argon2i>`.
+
 This creates an encoder named ``harsh``. In order for a ``User`` instance
 to use it, the class must implement
 :class:`Symfony\\Component\\Security\\Core\\Encoder\\EncoderAwareInterface`.
@@ -172,3 +178,5 @@ you must register a service for it in order to use it as a named encoder:
 
 This creates an encoder named ``app_encoder`` from a service named
 ``app.password_encoder_service``.
+
+.. _`libsodium`: https://pecl.php.net/package/libsodium