I have to say, I find it remarkably ironic that a researcher developing surveillance technologies has this much concern over being surveiled. I'm also inclined

I have to say, I find it remarkably ironic that a researcher developing surveillance technologies has this much concern over being surveiled. I'm also inclined to note that the argument "these technologies with obvious, profound antisocial uses have some feasible prosocial uses also" doesn't justify the work. Having gotten that off my chest; you're probably worrying about nothing, at least in terms of impact on your day-to-day activities- if the U.S. or aligned nation started curtailing the travel of computer scientists, it would be all over HN for weeks. Maybe if you want to go work for your country's intelligence agency someday (an obvious move, with your interests) they might look over your file before an interview. But perhaps in that case, contacts with Chinese researchers would be seen as an asset- the CIA and similar organizations have been known to try to recruit cooperative foreign-employed scientists in interesting fields, for various purposes, and to use their own experts in those fields to make contact. It might matter if you're a "real academic," i.e., affiliated with a university and conducting your research in "conventional" settings. For an academic to not be talking to out-of-country colleagues would look pretty odd, in most fields. But if you're just some dude in your basement chatting with Chinese espionage experts, that might raise some red flags. :)