As I read in the "Government use" section in the VPN blocking article on Wikipedia. It seems that Iran and China (used to) block access to use VPN software. I'd like to widen the scope of the question and apply it on any type of software, not specifically VPN or encryption software.
On what grounds can a government delegalise the use of specific software? And is delegalization of (specific) software compliant with international laws (human rights)?