Transparency of Operations

Definition

Transparency of operations is an important theme that emerged in the analysis of the biometric security devices. Transparency can have two meanings: (1) to be easily detected or seen through (visibility), and (2) to be readily understood. In interface designs these definitions are often in conflict, where making the operations of the system detectable and visible may make the system harder to understand, especially if the visible operations are complex. On the other hand, hiding information to make things apparently easier to understand is often in conflict with supporting a deeper understanding that comes from having the operations of the system visible.

Transparency has a number of dimensions and implications that are important for usability:

• Understandability: The application structure, navigation, procedures, features and terminology should be comprehensible for users.
• Learnability: The usage of the application or hardware device should exhibit a gradual learning curve and encourage exploration.
• Self-descriptiveness: This is also called "affordance" or "obviousness" and is the system's ability to speak for itself. When the application is presented to the user, it should be intuitively obvious how the system operates and what kind of tasks can be achieved.
• Feedback: This refers to whether there is an accessible, clear, and timely indication and response to user's actions.
• Metaphors: Metaphors support the transfer of real world knowledge into applications.

Transparency and Trust

The issue of transparency is not unique to biometric security applications and devices, but it does have an especially important role. In order to be used and accepted, users must come to trust the biometric systems and be willing to replace their old password methods. It is understandable that all new things will may be met with criticism and resistance. But it is even more difficult for biometric authentication systems to be accepted because of their long association with forensic science and science fiction. People often have misconceptions about the capabilities and implications of biometric security devices. Hiding the internal operations of the systems in an attempt to make them easier to understand does little to dispel the myths and fears. Instead, a more valuable approach may be to make the users understand the inner workings of these systems, including how the biometric features are captured, extracted, stored, and used. In the next section, several commercially available products are evaluated against this concept of supporting transparency through visibility.

Device Specific Discussions

• Understandability:
  The U.are.U Personal biometric system is a good example of supporting visibility of operations. For example, U.are.U Personal's "One Touch Internet" feature illustrates how a single sign-on (SSO) entry is created by asking the user to type the credentials in a form and then drag and drop it to the corresponding field on the web page. In contrast, the SSO entries are created automatically and invisibly in the "SecureSession" feature of the SecureSuite software that is used with the Authenticam and Targus Defender products.

  In another example, the BioconX software used in the Sony Puppy system has two front-end parameters that can be adjusted: MergeThreshold and MinutiaMin. Both parameters are intuitively named to suggest the value that they adjust, and both definitions are documented in the user manual. In contrast, BioPassword has two front-end parameters and one back-end parameter, and two of the three parameters are called Security and the another one is called Enrollment. The role of each parameter is not outlined in the interface, and the software does not have a user manual. Further, while the iris and fingerprint products all showed some representation of the biometric information being captured, BioPassword remains a mystery. It does not give even a glimpse of how keystroke dynamics are measured.

• Learnability:
  All the applications were relatively easy to learn, but there were two training features that are notable. BioconX has a built-in enrollment tutor that mimics the authentication process, and in which the user receives scores on how successful their authentication attempts are. BioPassword, on the other hand, has "user training cycles" in which the user repeatedly types in their user name and password in order to create a new template, without receiving any feedback. So in a sense, this only "trains" the computer not the user.
• Self-descriptiveness:
  The file encryption function of BioconX is an example of poor self-descriptiveness. This function appears to authenticate the user via biometrics when the user attempts to open the encrypted file, but really the "authentication" is done at sign sign-on and the actual operations are invisible.
• Feedback:
  U.are.U Personal is the only application that has multiple forms of feedback: visual, auditory, and animations. U.are.U Personal, BioconX, and SecureSuite all allow the user to adjust the form or the combination of feedback. U.are.U Personal's unique animation feedback is a good example of telling users their consequences of their actions, in contrast to the generic error messages in SecureSuite and BioconX. BioPassword has very poor feedback with the only communication being cryptic error messages.
• Metaphors:
  In U.are.U Personal, when a file is encrypted a key symbol appears on the file icon. In SecureSuite, a product logo is presented. The first one is better because it draws on an analogy with real world security.

This page is part of a project on the Usability and Acceptability of Biometric Security Devices.