Cypriot ISPs could not enforce HTTPS URL entries from the NBA blocklist because SSL/TLS interception was not deployed; connections to port 443 for blocked domains simply timed out with no block page or user notification, meaning HTTPS entries were effectively under-blocked.
From 2017-ververis-internet — Internet Censorship Capabilities in Cyprus: An Investigation of Online Gambling Blocklisting
· §4.1
· 2017
· E-Democracy
Implications
In regulatory blocking regimes without SSL/TLS interception capability, HTTPS is sufficient to defeat URL-level blocking; circumvention tools should ensure all control-plane and proxy traffic runs over TLS to reduce the ISP's ability to identify specific URLs or paths.
Absence of a block page on HTTPS makes censorship invisible to users; circumvention tools targeting similar regulatory environments should detect silent connection failures (timeouts vs. block pages) to distinguish censorship from network errors.