not achieve. One of the major problems that keystroke dynamics runs into is that a person's typing varies substantially during a day and between different days and may be affected by any number of external factors. Because of these variations, any system will make false-positive and false-negative errors. Some successful commercial products have strategies to handle these issues and have proven effective in large-scale use in real-world settings and applications. Legal and regulatory issues Use of keylogging software may be in direct and explicit violation of local laws, such as the U.S. Patriot Act, under which such use may constitute wire-tapping. This could have severe legal penalties. See spyware for a better description of user-consent issues and various fraud statutes. Patents P. Nordström, J. Johansson. Security system and method for detecting intrusion in a computerized system. Patent No. 2 069 993, European Patent Office, 2009. Other uses Because human beings generate keystroke timings, they are not well correlated with external processes. They are frequently used as a source of hardware-generated random numbers for computer systems. See also Fist (telegraphy) References Other references Checco, J. (2003). Keystroke Dynamics & Corporate Security. WSTA Ticker Magazine, . iMagic Software. (vendor web-site May 2006). Notes: Vendor specializing in keystroke authentication for large enterprises. AdmitOne Security - formerly BioPassword. (vendor web-site home [Web Page]. URL . Notes: Vendor specializing in keystroke dynamics Garcia, J. (Inventor). (1986). Personal identification apparatus. (USA 4621334). Notes: US Patent Office - Bender, S and Postley, H. (Inventors) (2007). Key sequence rhythm recognition system and method. (USA 7206938), Notes: US Patent Office - Joyce, R., & Gupta, G. (1990). Identity authorization based on keystroke latencies. Communications of the ACM, 33(2), 168-176. Notes: Review up through 1990 much cited Monrose, F. R. M. K., & Wetzel, S. (1999). Password hardening based on keystroke dynamics. Proceedings of the 6th ACM Conference on Computer and Communications Security, 73-82. Notes: Kent Ridge Digital Labs, Singapore Young, J. R., & Hammon, R. W. (Inventors). (1989). Method and apparatus for verifying an individual's identity. 4805222). Notes: US Patent Office - Vertical Company LTD. (vendor web-site October 2006). Notes: Vendor specializing in keystroke authentication solutions for government and commercial agencies. Lopatka, M. & Peetz, M.H. (2009). Vibration Sensitive Keystroke Analysis. Proceedings of the 18th Annual Belgian-Dutch Conference on Machine Learning, 75-80. Coalfire Systems Compliance Validation Assessment (2007) https://web.archive.org/web/20110707084309/http://www.admitonesecurity.com/admitone_library/AOS_Compliance_Functional_Assessment_by_Coalfire.pdf Further reading User interfaces Biometrics