Washington - News of a massive surveillance effort led by the secretive National Security Agency has sent web users scrambling to find new ways to avoid tracking.
It might have seemed paranoid not long ago when netizens used tools to hide their tracks, "shred" data or send self-destructing messages.
Web anonymisers, encryption programmes and similar tools have been available for years, but have been often associated with hackers, criminals and other "dark" elements on the internet.
"I think the notion of what is an unreasonable level of paranoia has shifted in the past couple of weeks," said Alex Stamos, an NCC Group security consultant and self-described "white hat" hacker.
Ironically, some tools for eluding detection come from US government-funded programmes aimed at helping people living under authoritarian regimes.
"The technologies usable in Tehran or Phnom Penh are just as usable in New York or Washington," said Sascha Meinrath, who heads a New America Foundation programme helping users maintain secure and private communications in totalitarian countries.
"The real problem is that many people don't know these tools exist and a lot of them are not usable to non-geeks."
One of the well-known programs used to hide online traces is Tor, a tool originally developed by the US military and now managed by the nonprofit Tor Project.
Tor, which has some 500 000 users worldwide, about 15% of whom are in the United States, can be used online to hide one's IP address, effectively blocking tracking by governments or commercial entities seeking to deliver targeted advertising.
Tor's development director Karen Reilly said the US government promotes the programme in other countries, but noted that it also protects against snooping from US law enforcement.
"We get inquiries from law enforcement saying criminals are using Tor, and they want to know where the back door is," she said.
"There is no back door. We are protecting you not only from your (internet provider) but from us. We never keep records that can identify our users."
Reilly brushed aside concerns about nefarious elements on the internet hiding behind Tor and similar programmes.
"Criminals are the ultimate early adopters of new technologies," she said.
If anonymous programmes were not available, Reilly said "they would find another option."