Todd E. Humphreys, (Aerospace Engineering, Ph.D., 2007); Paul Kintner and Mark Psiaki, professors of Electrical and Computer Engineering; Brent Ledvina, (Electrical Engineering, Ph.D. 2004); demonstrated the first known GPS spoofing attack, where a hacker can fool a targeted GPS receiver to misestimating its position, time or both. This has guided the development of a new generation of spoofing detection countermeasures to ensure the security of civilian GPS