> These "constrained devices" come up so often in discussions about costs of cryptography, yet people rarely tell what exactly they are talking about. Dependin

> These "constrained devices" come up so often in discussions about costs of cryptography, yet people rarely tell what exactly they are talking about. Depending on how difficult you want to be, you can mean different things. If you're being reasonable, you might for example think of a $5 retail price wifi-enabled lightbulb. It might use a chip such as the ESP8266 with 80 KB of memory. Depending on how efficient the SSL library is, supporting 4096-bit RSA on these chips can be a real squeeze, so some SDKs only support 2048-bit. But it's still a 160 MHz chip, so it can run grown-up cryptography. If you want to impose nigh-impossible requirements to torpedo the whole proposal, then demand the cryptosystem work on the tiny sips of power available to contactless bank cards and ten-year-battery-powered smart gas meters; and that it work for automotive door locking where their budget is like $0.02 per chip.