.. index::
single: Security; How to Migrate a Password Hash
In order to protect passwords, it is recommended to store them using the latest
hash algorithms. This means that if a better hash algorithm is supported on your
system, the user's password should be rehashed using the newer algorithm and
stored. That's possible with the migrate_from option:
- Configure a new Encoder Using "migrate_from"
- Upgrade the Password
- Optionally, Trigger Password Migration From a Custom Encoder
When a better hashing algorithm becomes available, you should keep the existing
encoder(s), rename it, and then define the new one. Set the migrate_from option
on the new encoder to point to the old, legacy encoder(s):
.. configuration-block::
.. code-block:: yaml
# config/packages/security.yaml
security:
# ...
encoders:
# an encoder used in the past for some users
legacy:
algorithm: sha256
encode_as_base64: false
iterations: 1
App\Entity\User:
# the new encoder, along with its options
algorithm: sodium
migrate_from:
- bcrypt # uses the "bcrypt" encoder with the default options
- legacy # uses the "legacy" encoder configured above
.. code-block:: xml
<!-- config/packages/security.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<container xmlns="http://symfony.com/schema/dic/services"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:security="http://symfony.com/schema/dic/security"
xsi:schemaLocation="http://symfony.com/schema/dic/security%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20https://symfony.com/schema/dic/security/security-1.0.xsd">
<security:config>
<!-- ... -->
<security:encoder class="legacy"
algorithm="sha256"
encode-as-base64="false"
iterations="1"
/>
<!-- algorithm: the new encoder, along with its options -->
<security:encoder class="App\Entity\User"
algorithm="sodium"
>
<!-- uses the bcrypt encoder with the default options -->
<security:migrate-from>bcrypt</security:migrate-from>
<!-- uses the legacy encoder configured above -->
<security:migrate-from>legacy</security:migrate-from>
</security:encoder>
</security:config>
</container>
.. code-block:: php
// config/packages/security.php
$container->loadFromExtension('security', [
// ...
'encoders' => [
'legacy' => [
'algorithm' => 'sha256',
'encode_as_base64' => false,
'iterations' => 1,
],
'App\Entity\User' => [
// the new encoder, along with its options
'algorithm' => 'sodium',
'migrate_from' => [
'bcrypt', // uses the "bcrypt" encoder with the default options
'legacy', // uses the "legacy" encoder configured above
],
],
],
]);
With this setup:
- New users will be encoded with the new algorithm;
- Whenever a user logs in whose password is still stored using the old algorithm, Symfony will verify the password with the old algorithm and then rehash and update the password using the new algorithm.
Tip
The auto, native, bcrypt and argon encoders automatically enable
password migration using the following list of migrate_from algorithms:
- :ref:`PBKDF2 <reference-security-pbkdf2>` (which uses :phpfunction:`hash_pbkdf2`);
- Message digest (which uses :phpfunction:`hash`)
Both use the hash_algorithm setting as the algorithm. It is recommended to
use migrate_from instead of hash_algorithm, unless the auto
encoder is used.
Upon successful login, the Security system checks whether a better algorithm is available to hash the user's password. If it is, it'll hash the correct password using the new hash. If you use a Guard authenticator, you first need to :ref:`provide the original password to the Security system <provide-the-password-guard>`.
You can enable the upgrade behavior by implementing how this newly hashed password should be stored:
- :ref:`When using Doctrine's entity user provider <upgrade-the-password-doctrine>`
- :ref:`When using a custom user provider <upgrade-the-password-custom-provider>`
After this, you're done and passwords are always hashed as secure as possible!
When you're using a custom :doc:`guard authenticator </security/guard_authentication>`,
you need to implement :class:`Symfony\\Component\\Security\\Guard\\PasswordAuthenticatedInterface`.
This interface defines a getPassword() method that returns the password
for this login request. This password is used in the migration process:
// src/Security/CustomAuthenticator.php
namespace App\Security;
use Symfony\Component\Security\Guard\PasswordAuthenticatedInterface;
// ...
class CustomAuthenticator extends AbstractGuardAuthenticator implements PasswordAuthenticatedInterface
{
// ...
public function getPassword($credentials): ?string
{
return $credentials['password'];
}
}
When using the :ref:`entity user provider <security-entity-user-provider>`, implement
:class:`Symfony\\Component\\Security\\Core\\User\\PasswordUpgraderInterface` in
the UserRepository (see the Doctrine docs for information on how to
create this class if it's not already created). This interface implements
storing the newly created password hash:
// src/Repository/UserRepository.php
namespace App\Repository;
// ...
use Symfony\Component\Security\Core\User\PasswordUpgraderInterface;
class UserRepository extends EntityRepository implements PasswordUpgraderInterface
{
// ...
public function upgradePassword(UserInterface $user, string $newEncodedPassword): void
{
// set the new encoded password on the User object
$user->setPassword($newEncodedPassword);
// execute the queries on the database
$this->getEntityManager()->flush($user);
}
}
If you're using a :ref:`custom user provider <custom-user-provider>`, implement the :class:`Symfony\\Component\\Security\\Core\\User\\PasswordUpgraderInterface` in the user provider:
// src/Security/UserProvider.php
namespace App\Security;
// ...
use Symfony\Component\Security\Core\User\PasswordUpgraderInterface;
class UserProvider implements UserProviderInterface, PasswordUpgraderInterface
{
// ...
public function upgradePassword(UserInterface $user, string $newEncodedPassword): void
{
// set the new encoded password on the User object
$user->setPassword($newEncodedPassword);
// ... store the new password
}
}
If you're using a custom password encoder, you can trigger the password
migration by returning true in the needsRehash() method:
// src/Security/CustomPasswordEncoder.php
namespace App\Security;
// ...
use Symfony\Component\Security\Core\Encoder\PasswordEncoderInterface;
class CustomPasswordEncoder implements PasswordEncoderInterface
{
// ...
public function needsRehash(string $encoded): bool
{
// check whether the current password is hash using an outdated encoder
$hashIsOutdated = ...;
return $hashIsOutdated;
}
}