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Add Fingerprint Scan-based Security to Your .NET Applications Today

It wasn't all that long ago that biometric authentication seemed like the kind of sci-fi technology that might never be practical outside of top-secret government laboratories. But believe it or not, you can build a fingerprint scanner into any .NET application you like just by following these simple instructions.

iometric recognition is one of the most reliable ways to confirm the identity of an individual. And by now, many people are undoubtedly familiar with the Microsoft Fingerprint Reader (see Figure 1).

Besides logging into a computer using a fingerprint scan from the reader, you can also use the application provided by the Fingerprint Reader to save your user IDs and passwords for web sites that require them. You can then use your fingerprint as a key to retrieve the authentication information to log in securely, thereby eliminating the hassle of remembering different sets of passwords for different sites.

Unfortunately, that's all you can do with the Fingerprint Reader. Microsoft does not provide an SDK to allow developers to incorporate the Fingerprint Reader into their applications. For this, you have to reply on third-party solution providers. Fortunately, there is one such provider available in the market: (Griaule provides the GrFinger Suite, a fingerprint recognition suite that comes with an SDK for integrating your fingerprint readers into your applications. (It works with Microsoft Fingerprint Reader, Digital Persona U.are.U 4000, SecuGen Hamster FDU02, Geomok (Testech) Bio-I, and Crossmatch USB Fingerprint Readers.).

In this article, I will show you how you can use the GrFinger SDK to integrate the Microsoft Fingerprint Reader into your .NET applications. In particular, you will build a Visitor Identification System whereby users visiting your office can register with their fingerprints at the reception desk (see Figure 2). Once a user is registered, the next time he visits the office he can simply scan his fingerprint and the system will register his visit. This application can also be adapted by schools for attendance taking purposes, such as in big lecture theaters where attendance must be taken rapidly and efficiently.

Figure 1. The Microsoft Fingerprint Reader in action.
Figure 2. The screen shot shows the completed Visitor Identification System application you will build in this article.

Obtaining the GrFinger SDK
There are three editons of the GrFinger SDK: FREE, LIGHT, and FULL. From Griuale's web site:

"The FREE Edition can be used for any non-commercial purposes and evaluation. Support is provided in forum.griaule.com. LIGHT Edition is intended for companies that would like to deploy GrFinger in many computers but does not need all of its speed. FULL edition unleashes all the GrFinger speed and allows you to access the fingerprint images and also features e-mail support."
In addition, images captured by the FREE and LIGHT editions are encrypted, and for the FREE version, there is an advertisement banner displayed on the captured image. Consult Griaule's website for full pricing information for each edition. For this article, I have used the FULL edition (special thanks to Griaule for kindly granting me the license).

To obtain the GrFinger SDK, visit: http://griaule.com/page/en-us/downloads.

Creating the Application
Once the GrFinger SDK is installed, you are ready to create the application. For this article, I used Visual Studio .NET 2003. Create a new Windows application and name it C:\Fingerprintreader.

First, you need to add the GrFingerxCtrl (an ActiveX control representing the GrFinger component) into your Toolbox. Right-click on Toolbox and select Add/Remove Items…. Check the GrFingerXCtrl Class (see Figure 3) and click OK.

The GrFingerXCtrl control will now appear in the ToolBox (see Figure 4).

Figure 3. Add the GrFingerXCtrl class into the ToolBox in Visual Studio.
Figure 4. Check the ToolBox to make sure the GrFingerXCtrl ActiveX control has been added successfully.

In the default Form1, populate it with the following controls (see also Figure 5):
  • PictureBox
  • Label
  • TextBox
  • ListBox
  • GroupBox
  • Button
  • AxGrFingerXCtrl

Figure 5. Populate the default Form1 with all the controls shown in the screen shot.
In addition, add a Timer control to the project. The Timer control will be used to clear away the user's information after his identity has been loaded from the database (after five seconds).

Also, add an ImageList control and add an image to it (via the Images property). This image is the one shown in the PictureBox control as shown in Figure 5.

Author's Note: I suggest you download the source code for this project in order to obtain the detailed settings for each control.

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