Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

D. Richard Kuhn

Computer Scientist

Biographical Information

Rick Kuhn is a computer scientist in the Computer Security Division at NIST, and is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE).  His research focuses on combinatorial methods in software verification and testing (, and extending these methods for assurance and explainability in AI and machine learning.  He has authored three books and more than 150 conference or journal publications on information security, empirical studies of software failure, and software assurance.  He co-developed the role based access control model (RBAC) used worldwide and led the effort that established RBAC as an ANSI standard. Before joining NIST, he worked as a software developer with NCR Corporation and the Johns  Hopkins University Applied Physics Laboratory. He received an MS in computer science from the University of Maryland College Park.

All publications (Google Scholar)

Significant papers (or at least ones that seem to get a lot of attention):

  • D.R. Kuhn, D.R. Wallace, A.M. Gallo, Jr., "Software Fault Interactions and Implications for Software Testing", IEEE Transactions on Software Engineering, vol. 30, no. 6, June 2004, pp. 418-421.
    AbstractDOI: 10.1109/TSE.2004.24 - investigates number of interactions required to trigger failures in various types of systems; basis for our combinatorial testing project.
  • D.R. Kuhn, "Fault Classes and Error Detection Capability of Specification Based Testing", ACM Transactions on Software Engineering and Methodology,Vol. 8, No. 4 (October,1999) - demonstrates existence of a hierarchy of fault classes that may be used to generate test more efficiently.  Others have extended the hierarchy based on more types of faults.
  • D. Ferraiolo and D.R. Kuhn, "Role Based Access Controls"Proceedings, 15th Natl. Computer Security Conference, 1992, pp. 554–563. --- the early paper on role based access control; includes basic formal definition.  This was unified w/ Sandhu et. al (1996) to create the standard model for RBAC (more on RBAC project site).

Professional activities:

  • Fellow, Institute of Electrical and Electronics Engineers (IEEE)
    Member, Association for Computing Machinery (ACM)
  • Co-editor, Resilient Security department, IEEE Security & Privacy
  • Co-editor, Securing IT department, IEEE IT Professional
  • Patents: "Implementation of Role Based Access Control in Multi-level Secure Systems", U.S. Patent #6,023,765.,
    "Oracle-free Match Testing of a Program Using Covering Arrays and Equivalence Classes", U.S. Patent #10,552,300. 
    U.S. Provisional Patent Application #62/842,616 “Data Block Matrix” (blockchain/DLT allowing block edits, to enable privacy requirements such as GDPR)
  • Past member of DARPA High Confidence Systems Working Group, IEEE Technical Committee on Operating Systems POSIX 1003.1, 1003.2 and 1201.2 working groups;
  • Past projects: development of software tools and conformance  test suites; methods for analyzing changes in formal specifications;  verification of cryptographic protocols; and the first formal definition of role based access control; IEEE POSIX working groups and developing parts of the POSIX Conformance Test Suite for IEEE 1003.1; and definition of software assurance requirements  for FIPS 140-1 (Security Requirements for Cryptographic Modules).


  • IEEE Reliability Society lifetime achievement award 'for contributions to the theory and empirical foundations of combinatorial testing', 2019
  • ACSAC 'Test of Time' paper award for 'Role Based Access Control:  Features and Motivations' (with D. Ferraiolo and J. Cugini), Annual Computer Security Applications Conference, 2019. 
  • IEEE Innovation in Societal Infrastructure Award, Institute of Electrical and Electronics Engineers, 2018 (for role based access control)
  • Best poster, Hot Topics in Science of Security, 2018, "What Proportion of Vulnerabilities can be Attributed to Ordinary Coding Errors?" (with Mohammad Raunak and Raghu Kacker)
  • IEEE Fellow (for contributions to access control and combinatorial test methods)
  • Silver medal award for scientific/engineering achievement, U.S. Dept. of Commerce, 2014
  • Excellence in Technology Transfer Award, Federal Laboratory Consortium Mid-Atlantic, 2009
  • Best Standards Contribution, NIST/ITL, 2008
  • Best Journal Paper Award, NIST/ITL, 2007
  • Outstanding Authorship Award, NIST/ITL, 2003
  • Gold medal award for scientific/engineering achievement, U.S. Dept. of Commerce, 2002;
  • Excellence in Technology Transfer Award, 1998, Federal Laboratory Consortium.
  • Bronze Medal, U.S. Dept. of Commerce, 1990;
  • Member, Beta Gamma Sigma honorary.


Combinatorial Methods for Explainable AI

David R. Kuhn, Raghu N. Kacker, Yu Lei, Dimitris Simos
This paper introduces an approach to producing explanations or justifications of decisions made by artificial intelligence and machine learning (AI/ML) systems

Aggregating Atomic Clocks for Time-Stamping

Temur Saidkhodjaev, Jeffrey M. Voas, David R. Kuhn, Joanna DeFranco, Phil Laplante
A timestamp is a critical component in many applications, such as proof of transaction ordering or analyzing algorithm performance. This paper reports on a
Created October 9, 2019, Updated July 23, 2020