In an earlier post I explained how to use TLS client authentication for AIR applications on Windows and Mac OS. Commenter Arlen asked how to do the same on Linux; unfortunately, TLS client authentication is not supported in AIR for Linux.
The first problem is that, unlike Windows and Mac OS, Linux doesn’t have a standardized, easily accessible certificate store available. Instead, AIR bundles its own certificate stores. (See this Adobe knowledge base article for information about managing those certificate stores.) Other Linux applications typically do the same. Even if client authentication was supported, it would have be configured separately for AIR applications versus other applications, thus making it much less useful than on Windows or Mac OS.
The second problem is that Linux doesn’t have a standardized, easily accessible HTTP stack that supports TLS client authentication—instead, applications have to bundle their own implementation. That, of course, doesn’t make it impossible for AIR to add this support, but it means it requires a non-trivial engineering investment.
To date, these two issues have kept us from adding TLS client authentication support on Linux. If you’d like to see it added, I encourage you to vote for it on the Adobe AIR Ideas site.