Randomize Filename in Paperclip

Here’s a quick tip that Jonathan Yurek, author of Paperclip, was kind enough to help me with. It’s a simple way to have a randomized filename for uploaded content. This is useful for security through obscurity, especially when used with Paperclip’s id_partition interpolation helper:

class Photo < Asset

  has_attached_file :image, :path => ":class/:attachment/:id_partition/:basename_:style.:extension"

  before_create :randomize_file_name

private

  def randomize_file_name
    extension = File.extname(image_file_name).downcase
    self.image.instance_write(:file_name, "#{ActiveSupport::SecureRandom.hex(16)}#{extension}")
  end

end

That would, for example, change an uploaded image named “DS_100.JPG” into:

http://example.com/photos/images/000/001/204/e15f64f5e7gjdo3e4ae58f4ed9j925f5.jpg

That makes it effectively impossible to guess the location of an image, provided that you don’t allow people to browse around the directories on your server. This is the same method of privacy protection that Flickr uses, and it ought to be enough for most non-governmental privacy needs :)