I have a Joomla 3.10 and a Drupal 9 site.
I want to migrate user passwords from Joomla to Drupal. I have seen that Joomla uses bcrypt and Drupal uses sha512 as the password encryption.
Is it possible to migrate user passwords from Joomla to Drupal? If yes, how can I do this?
If the other site uses Phpass (Portable PHP password) password hashes, which are used from Drupal and from Joomla (starting with versions 2.5.18 and 3.2.1), then it's possible to migrate passwords. Drupal is able to handle Phpass password hashes that start with $P$, which are MD5 hashes normally used by phpBB3, that start with $H$, still MD5 hashes, that start with U$, which are Drupal 6 password hashes updated by user_update_7000(), and that start with $S$, the usual SHA512 password hashes Drupal 7 uses.
For other password hashes, a module should create a service that implements PasswordInterface and that verifies the password entered from the user matches the password hash stored in the database in PasswordInterface::check().
As reference, the default code used by Drupal core is in the PhpassHashedPassword class.
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No. If the password hash algorithms are different you cannot migrate the hash with Drupal Core alone without installing a module that changes the algorithm, if such module exists.
The answer depends on a lot of different factors.
Drupal uses not only sha512, but also a certain salt strategy, certain loop strategy, and data storage strategy in the password field in the database. Drupal core has a concept of supporting a few different password strategies and contributed modules can support others.
I did find this Password Bcrypt module for Drupal 7 which could be helpful to you.
