[Cryptography] Hacking spread spectrum clocking of HW ?

[Henry Baker]

FYI --

https://www.maximintegrated.com/en/app-notes/index.mvp/id/1995

"In 1975 the Federal Communications Commission (FCC), the government agency that regulates radio frequency (RF) emissions in the United States, enacted new regulations called FCC Part 15.  These were not directed at controlling equipment such as radio and TV transmitters, or aircraft-navigation and emergency beacons that deliberately radiate high-power RF energy.  Instead, these regulations sought to control equipment that did not deliberately radiate RF energy such as televisions, automobiles, and low-power, unregulated RF radiators such as walkie-talkies and electronic remote controls.  During the 1980s and 1990s, electronic devices from microwaves to cell phones proliferated.  Cross interference between these devices became a problem.  Traditional methods to address radiated emissions issues consisted of shielding, careful board layout, as well as filtering to reduce undesired radiated emissions.  As electronics became smaller, another technique, Spread Spectrum, borrowed from 
communication applications was used.  This article gives a background and history of spread spectrum and describes how it is used today as a technique to reduce radiated emissions in consumer electronic equipment."

Q: How hard is it to diddle with the spreading codes on these clocking sources?  I'd like to experiment with some longer codes.