Inexpensive Two Factor Authentication

Two Factor authentication is a means by which a user’s identity can be confirmed in a more secure manner. Typically, the user supplies a username and password, the first factor, and then an additional piece of information, the second factor. In theory, providing this additional information proves the user is who they say they are. Two different types of factors should be used to maximize security.

There are three general types of factors that are used. They are as follows (quoting from Wikipedia):

  • Human factors are inherently bound to the individual, for example [[biometrics]] (“Something you are”).
  • Personal factors are otherwise mentally or physically allocated to the individual as for example learned code numbers. (“Something you know”)
  • Technical factors are bound to physical means as for example a pass, an ID card or a token. (“Something you have”)

While Two Factor authentication can be secure, the security is often compromised through the use of less secure second factors. For instance, many institutions use a series of questions as a second factor. While this is somewhat more secure than a single username and password, these questions are often generic enough that they can be obtained through social engineering. This is an example of using the same factor twice, in this case, Personal factors. Personal factors are inexpensive, however, often free to the institution requiring the security.

On the other hand, use of either Human or Technical factors is often cost prohibitive. Biometrics, for instance, requires some sort of interface to read the biometric data and convert it to something the computer can understand. Technical factors are typically physical electronic devices with a cost per device. As a result, institutions are unwilling to put forth the cost necessary to protect their data.

Banks, in particular, are unwilling to provide this enhanced security due to their large customer base and the prohibitive cost of providing physical hardware. But, banks may be willing to provide a more cost effective second factor, if one existed. Australian inventor, Matt Walker, may be able to provide such a solution.

Passwindow is a new authentication method consisting of a transparent window with seemingly random markings on it. The key is to combine these markings with similar markings provided by the application requiring authentication. The markings are similar to those on an LED clock and combining the two sources reveals a series of numbers, effectively creating a one-time password. The Passwindow provides a Physical factor, making it an excellent second factor. The following video demonstrates how Passwindow works.

What makes Passwindow so incredible is the how inexpensive it is to implement it. The bulk of the cost is in providing users with their portion of the pattern. This can easily be added to new bank cards as they are sent out, or provided as a second card to customers until they require a new card. There is sufficient space on existing bank cards to integrate a clear window with the pattern on it.

Passwindow seems to be secure for a number of reasons. It’s a physical device, something that cannot be socially engineered. In order for it to be compromised, an attacker needs to have a copy of the segment pattern on your specific card. While users generally have a difficult time keeping passwords safe, they are exceedingly good at keeping physical objects secure.

If an attacker observes the user entering the generated number, the user remains secure because the number is a one-time password. While it is theoretically possible for that number to come up again, it is highly unlikely. A well written generator will ensure truly random patterns, ensuring they can’t be predicted. Additional security can be added by having the user rotate the card into various positions or adding additional lines to the card.

If Passwindow can find traction, I can see it being integrated into most bank cards, finally providing a more secure means of authentication. Additionally, it brings an inexpensive second factor to the table, giving other institutions the ability to use enhanced security. This is some pretty cool technology, I’m eager to see it implemented in person.


Leave a Reply
