plugin.rb

# name: altpwd
# about: enable alternative password hash algorithms
# version: 0.1
# authors: Jens Maier

require 'digest'

after_initialize do

  module ::AlternativePassword
    def confirm_password?(password)
      return true if super
      return false unless self.custom_fields.has_key?('import_pass')
      salt, password_hash = self.custom_fields['import_pass'].split(':')
      if password_hash == AlternativePassword::hash_password(password, salt)
        self.password = password
        self.custom_fields.delete('import_pass')
        return save
      end
      false
    end

    def self.hash_password(password, salt)
      Digest::SHA1.hexdigest(salt + password)
    end
  end

  class ::User
    prepend AlternativePassword
  end

end