Encryption and data interception --- Vladimir, let me add to the responses by Bennette and Tracy with a particular look at the role of encryption.

If data that are traveling through the fibre (or any other medium - copper, wireless, mobile links, etc) are not encrypted, than the owner of the infrastructure (be it telecom companies, or a caffee which operates the WiFi you are connected to) has a technical capability to intercept and surveil (even alter it). If they are encrypted, however, it is not possible.

Then, the question is who does the encryption? Take a look at the 1.3 and part on encryption for some details, but in a nutshell - we can encrypt data - on our ends, at our devices: encryption of the content on our computers (such as with PGP applications) - in transit, which depends on the service we use and whether it has encryption embedded (eg. WhatsApp, Telegram, Zoom and most web-based services that use HTTPS encrypt the data during the exchange from our devices to their servers) - at the servers' end, in the cloud: this also depends on the service and providers we use: if the cloud is ours (ie servers are hosted by our institution) we can make the content to be encrypted; if it is a public cloud (say Google, Microsoft or other) then it's up to them - in most cases, cloud storage is not encrypted by default (unless you pay extras or so - but this is changing now).

Each of these points (our end, transit, and servers) can be a point where data can be intercepted if they are not encrypted. On our ends, a hack could enable the adversary to access our data (even before they get encrypted). In transit, as well as on servers, companies owning the medium (cables, satellites, etc) and servers could possibly intercept data - or could the law enforcement (depending on the jurisdictions and laws).

I hope this helps?

Source author: Vladimir Radunovic vladar@diplomacy.edu