def security_token(params = {})
      params = params.dup.stringify_keys
      params.update({
        'crop' => params['crop'] ? 'crop' : nil,
        'id' => id
      })
      PictureAttributes.secure(params)
    end
def security_token(params = {})
      params = params.dup.stringify_keys
      params.update({
        'crop' => params['crop'] ? 'crop' : nil,
        'id' => id
      })
      PictureAttributes.secure(params)
    end
Returns a security token for signed picture rendering requests.

 Pass a params hash containing:

   size       [String]  (Optional)
   crop       [Boolean] (Optional)
   crop_from  [String]  (Optional)
   crop_size  [String]  (Optional)
   quality    [Integer] (Optional)

 to sign them.