silent90

Language extension for maintenance of legacy application sounds a little bullsh1t to me.

0) If the application needs checks on anything (at the cost of performance) then higher level language (like C++) should be chosen at design time. No use for new application. 1) Existing applications will NOT port directly. Real-life applications are tightly coupled with supported compiler(s), so the compiler would need the update. Errors/exceptions (like overflows) would need handling and changes in logic. It could only deny read/write from illegal area, but without the feedback. The speed is also a major thing. Boundary check could possible prevent some bugs, but the performance will drop dramatically (example: commonly used libs like OpenSSL).

One use case I see is to add an extension (like GCC's for instance) for an existing compiler which does this. User could build a slower debug application and spot the silent errors during testing. An implementation thing, not the language extension.

I'm sensing a huge incomprehension in a great amount of posts. The key is to know the purpouse of tools. C is a "close-to-the-metal" type language. You can control a low-level things, execution time, "number of hops" when writing data, etc. If you want a friendly language with "no segfaults, no memory leaks" then go higher level (which in many cases is a better choice, i.e. a GUI desktop application with no performance constraint). If you have a problems wrigint in C then you simply still can't C and using the wrong tool for the task.

"But C? C's dead. It's the language for old programmers who want to debate section A.6.2 paragraph 4 of the undefined behavior of pointers"

Someone has to build the low-level stuff. Dear boys in too-tight pants and a hippie mustache: your high-level things and gluten-free snacks does not grow on trees.

Capturing the CPU instructions by a side-channel is indeed possible but the "real-life, working" use of the method described here is questionable for me. CPU in modern phones runs above 1GHz. USB sound card they're using provides max 192kHz which allows max 96kHz signal. 4 orders of magnitude less. There's also a lot of noise from different circuitry (GPU, display, wireless comm.) and laptop's noise as well which will obfuscate the signal.

I would recommend low power nRF51 chips. It's a Cortex M0 with integrated 2,4GHz radio. You can use is for Bluetooth Low Energy and communicate with other chips / smartphones / etc (manufacturer provides a BLE stack) or your own simple protocol. There are some modules below $10, but those would require additional USB chip (like ft232 or $2 pl2303 / ch341 module).

If you need a long distance (like 1km) communication then you need a "larger" radio which works in ISM band. For the cheapest solution I'd go with mass produced devices - two WiFi APs with 2 directional antennas + some custom boards ob both sides or APs with open firmware like openWRT.