They would have to check logs at the VPN provider, unless the VPN provider has provided them with backdoor access for other reasons.
VPNs keep your traffic hidden between you and their entry point (encrypted), and then you’re anonymized at the exit point, so only the VPN provider knows what you’re looking at. If they don’t keep logs then no one will know what you’re doing.
Unless the government has spyware on your machine, or just checks with Twitter to see which Brazilian users are still logged on, they’re not going to know what’s up.
Latest Answers