Shopliebe Configurable Password Strength allows to configure the required password strength by following parameters:
- length
- must contain both uppercase and lowercase characters (yes / no)
- must contain special characters (yes / no)
More config parameters are in development. This extension modifies javascript and backend validation without hacking into your templates. The modified validation is only active for new and changed passwords. It's disabled for the "change password" function in the admin panel.