We estimate that by 2025, Signal will require approximately $50 million dollars a year to operate—and this is very lean compared to other popular messaging apps that don’t respect your privacy.
It’s difficult to maintain privacy in a P2P environment. In naive implementations, your IP address will be visible to all the peers you connect to. This is the case in e.g. BitTorrent.
Signal has this issue with video/voice calls as well; by default they operate on a P2P basis for performance reasons, and they expose your IP address to the second party. Signal has an option in the settings to relay voice/video calls through their servers specifically to mitigate this.
There are some workarounds for anonymizing P2P, like routing through Tor or I2P. Tor, however, has known exploits and is probably not suitable if you need to hide your activity from advanced adversaries like world governments (e.g. political dissidents, journalists, etc.)
I2P sounds interesting but I’m not deeply familiar with it. I understand that I2P clients also act as relay nodes, which puts an additional bandwidth burden on users. I’m not sure if I2P is more resilient against government-level attacks than Tor. I’d be interested to hear from anyone who is more familiar with the protocol.
If you’re using it for personal correspondence with people you know and trust, that’s probably fine. However, a secure and private communications platform should support more extreme use cases as well.
If you’re a journalist, for example, you might need to communicate with people you do not know or trust. You could realistically be talking to someone who wants to kill you, or who is being monitored by people who want to kill you, particularly if you are covering high-profile political issues or working with whistleblowers (or are yourself a whistleblower). Even revealing information as broad as what city you’re in (which would be revealed by your IP address) could be a risk to your physical safety.
Even though I do not personally face such high-level threats in my life, I feel better using services that allow for the possibility. Privacy is a habit, and who knows what tomorrow might bring?
