Circumvention tools like pluggable transports (PTs) are designed with this principle in mind, to strategically target weaknesses in the tools censors use for censorship or else to make use of infrastructure that a region relies on for daily life. This assumes that a censor will trivially be able to reverse-engineer or run their own instance of the system in order to find and exploit any weakness that would help the censor’s blocking efforts. Kerchkoff’s principle: to design tools that are cryptographically secure even if everything about the system, except the secret key, is known to the censor. When developing circumvention tools then, it is important to use To mitigate these costs, censors typically rely on automated tools that are programmed to inspect and filter traffic flows based on strategically constructed rules that don’t simultaneously disrupt essential services.

As Internet connectivity becomes essential for the transactions of day-to-day life, complete Internet shutdowns become more and more costly, both monetarily and in terms of public perception. Internet shutdowns, for example, are very costly for businesses, both those based inside the censored region and those relying on patronage from the region. However, censors still have constraints that can be exploited when designing circumvention tools. When talking about Internet censorship and circumvention, it is generally safe to assume that state-level censors have significant resources that can be leveraged to run, block or undermine any tool that can be developed for circumvention. This post is intended for readers with interest and some existing knowledge of Internet censorship and resistance practices and techniques.

Fte tor bridge vs obfs3