Once a tool primarily used by law enforcement to help identify criminals, biometric 

technologies increasingly are being used 

by government and the private sector to 

authenticate a person’s identity, provide security at the 

nation’s borders and restrict access to secure sites—both 

buildings and computer networks.New software and other 

tools that can be used to help build improved biometric 

applications are now available from the National Institute 

of Standards and Technology (NIST). 

Most biometric systems are “unimodal,”meaning they rely 

on a single distinguishing physical characteristic—such 

as a fngerprint—for authenticating identity. However, 

using a single feature can present problems. Poor illumination can make a face image unrecognizable; dirty or 

damaged sensor plates can affect fngerprint equipment. 

A multimodal system that has several sources of information, including fngerprint, face, and iris data, can be more 

fexible and reliable. However, most biometric equipment, 

including the sensors that capture data and the database 

that stores the information, is not interoperable. Organizations must either purchase a complete system or develop 

“middleware”—custom integration software—to link 

together applications. 

Despite existing efforts, building modern biometric applications (or “ clients”) that are fexible with respect to these 

problems—changes in sensors, workfow, confguration, 

and responsiveness—remains both diffcult and costly. 

The Multimodal Biometric Application Resource Kit, 

or MBARK, reduces the complexity and costs of implementing such an application. MBARK is public domain 

source code that may be leveraged to develop the next 

generation of biometric and personal identity verifcation 

applications. 

Incorporating the MBARK libraries can yield a variety of 

enhancements critical for the success of any real-world 

system. For example, MBARK provides a usabilitytested and consistent user 
 

 

 

 

 

 

MBARK represents a ready response to the National Biometric Challenge of developing middleware techniques 

and standards that will permit “plug-and-play” capabilities for biometric sensors. This Challenge was issued by 

The National Science and Technology Council’s Subcommittee on Biometrics & Identity Management. 

interface. MBARK provides operators the means to 

quickly recover from both minor mistakes and major 

hardware failures. In addition, the use of Extensible 

Markup Language (XML) facilitates true sensor interoperability via plug-ins and allows for changes in workfow 

on-the-fy. 

The following are just some of the features of MBARK 

that make it robust and fexible with respect to changes in 

sensors, workfow, confguration, and responsiveness. 

Provides a consistent user interface 

Often biometric systems change interfaces depending on 

which sensors are being used. MBARK, however, provides 

a consistent and user-centered interface, reducing errors 

and minimizing the need to retrain users as vendors 

develop new sensors and software. User-centered design 

is a formal process that helps ensure the effciency, effectiveness, and user-satisfaction of a system throughout the 

system’s lifecycle. 

Allows users to recover quickly and easily 

from mistakes 

Signifcant costs may accompany any system that does 

not allow recovery from both common and uncommon 

mistakes. With MBARK, an operator may not only easily 

recover from mistakes, but may also save a snapshot of a 

session (in the form of an XML fle), allowing that session 

to be re-loaded at a later time. 

Provides fexible user confguration 

The workfow of a system is the logic that defnes the order 

in which things happen. Typically, biometric clients have a 

fxed workfow—for example, a right index fngerprint is 

always followed by a left index. A fxed workfow means 

that the tasks to be performed can never be changed. 

Alternatively, a highly confgurable biometric client 

empowers users to defne and experiment with various 

biometrics and workfows. With the workfow described 

in its XML fles, MBARK allows users to defne precise 

custom workfows specifcally tailored to their needs. 
 

 

 

 

Adjusts workfow automatically 

Defning a workfow that accommodates mistakes 

becomes more complex as “edge cases” are added. For 

example, how should the system behave if a fngerprint 

sensor detects that a fnger is missing, but the operator 

has not indicated such? MBARK will warn the operator 

if it detects a confict between what was expected and 

what was captured. 

Multitask whenever possible 

Users expect modern applications to be responsive to their 

input at all times—during initialization, startup, capture, 

task editing, and so on. How does a user distinguish 

between a long-running operation and a system that is 

simply “frozen”? MBARK uses a natively multi-threaded 

architecture to allow as much “background” processing 

as possible. For example, for some sensors, initialization 

can take up to 30 seconds. MBARK will initialize sensors 

simultaneously. Applications that don’t do this force the 

user to wait for each sensor in turn. 

Provides true sensor interoperability 

MBARK uses a plug-in style mechanism that allows 

true sensor interoperability based on a unifed application programming interface (API). This common digital 

interface has been used to successfully integrate face 

cameras, fngerprint scanners, and iris sensors. To add 

a new sensor to MBARK, developers only have to write 

the code necessary to communicate with that particular 

sensor. All of the user interfaces, workfow logic, and 

‘plug-and-play’ capabilities are written already. 

Open and free 

MBARK source code is public domain. This means that 

anyone is free to modify MBARK for their application with 

minimal commercial and intellectual property restrictions. 
 

 

 

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ReLATeD PRojeCTS AND CAPABILITIeS 

The following is a list of related projects and capabilities that are under development within the 

NIST Biometric Clients Lab. 

The frst two projects, the Adaptive Sensor Testbed 

and the Biometric Clients Confguration Language 

(BiCCL) have general applicability to multimodal 

biometric systems. The second two projects, NBIS.Net 

and the Data Interchange Code Generator, are more 

focused towards the multimodal biometric application 

developer. 

Adaptive Biometric Client Testbed 

The NIST Biometric Clients Lab has initiated research into 

biometric systems that automatically adapt to a user’s 

need. The basic concept of an adaptive client is straightforward. First, as a user approaches the biometric sensors, 

a signal is sent to the system that indicates a user’s 

desires or requirements. Then, the system acts on that 

signal, enabling or disabling various features based on 

those user requirements. By the time the user is ready to 

present their biometrics, the system has been automatically confgured in a personalized fashion. 

Biometric Clients Confguration Language 

The Biometric Clients Confguration Language (or BiCCL) 

is a simple, domain specifc language for describing 

biometric client confgurations and workfows. The 

Biometric Clients Lab has developed a compiler that 

transforms BiCCL into an MBARK XML confguration fle, 

which greatly simplifes the confguration of any MBARKbased system. 

NBIS.Net 

NBIS.Net is the Biometric Clients Lab proof-of-concept 

interoperability layer so that the NIST Biometric Image 

Software (NBIS) tools can be effciently called directly 

from the .NET runtime (i.e., — no inter-process communication or fle system interaction is required). 

The NBIS project is a suite of public domain biometric 

libraries and applications. In includes (a) a neuralnetwork based fngerprint pattern matcher, (b) a fngerprint minutiae detector, (c) the NIST Fingerprint Image 

Quality (NFIQ) metric, (d) a reference implementation of 

the ANSI/NIST-ITL 1-2007 Data Format for the Interchange 

of Fingerprint, Facial, Scar Mark & Tattoo (SMT) Informa 

tion, and (e) JPEG 2000 and WSQ image compression and 

decompression algorithms. 

Data Interchange Code Generator 

The NIST Biometric Clients Lab is currently developing a 

tool to automatically generate class libraries for use in 

reading and writing biometric information in the ANSI/ 

NIST-ITL family—ANSI/NIST-ITL1-2000, Electronic Finger 

print Transmission Specifcation (EFTS), ANSI/NIST-ITL2007, Electronic Biometric Transmission Specifcation 

(EBTS), or any ANSI/NIST customized application profle. 

The tool can generate code in any language for which a 

custom ‘codec’ is written. 
 

For comments, questions, or inquiries (including source code), please contact mbark@nist.gov. 

Although it is being developed at NIST, MBARK is sponsored by the Standards Portfolio of the Department of 

Homeland Security’s Science and Technology Directorate. 

NIST has recently completed a handbook that provides an overview of the user-centered design process, along 

with examples of how the process can be specifcally tailored for biometric systems. This 75-page handbook 

can be downloaded from NIST Biometrics Usability project homepage, http://zing.ncsl.nist.gov/biousa/. 

MBARK was developed at NIST by employees of the Federal Government in the course of their offcial duties. 

Pursuant to Title 17 Section 105 of the United States Code, this software is not subject to copyright protection 

and is in the public domain. NIST assumes no responsibility whatsoever for use by other parties of its source 

code or open source server, and makes no guarantees, expressed or implied, about its quality, reliability, or any 

other characteristic. 

Specifc hardware and software products identifed in this open source project were used in order to 

perform technology transfer and collaboration. In no case does such identifcation imply recommendation or 

endorsement by NIST, nor does it imply that the products and equipment identifed are necessarily the best 

available for the purpose. 

Biometric Clients Lab 

Image Group 

Information Access Division 

Information Technology Laboratory 

mbark@nist.gov 

http://mbark.nist.gov 

November 2008