Force password change on email activation

Today I'm looking for a recipe to force drupal to change a password on activation email page on first login.

I tried to alter my user_reset_pass form,开发者_开发百科 and I know how to print password confirmation fields, but I don't have any idea how to override verification of that form to check if password is set and proper value.

Maybe You can give me some hints to do that?

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Check this module out: Force Password Change