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I’m not a crypto expert, but you can get 8 bit Atmel / Microchip AVRs with AES units on them (for example), are “special” lightweight algorithms actually needed
by fredoralive 4y ago
I’m not a crypto expert, but you can get 8 bit Atmel / Microchip AVRs with AES units on them (for example), are “special” lightweight algorithms actually needed, or should we just be encouraging the use of MCUs with suitable accelerators for proven algorithms?
- jvanderbot 4y agoThey're also expensive. At least last time I priced them out, they cost more than the radio and MCU.
- fredoralive 4y agoI was thinking of on chip accelerator units / peripherals, like the AVR Xmega AES example, rather than external chips.
- zokier 4y agoAfaik these LWCs are supposed to also be easier to implement in HW (=smaller die area/gate count), but I'm also wondering is the difference really meaningful especially with current manufacturing tech? I imagine there are limits on die size reductions where the returns really start diminishing very quickly.
- Avamander 4y agoMost microcontrollers are done on as large nodes as possible to reduce cost, so probably?
- hra5th 4y agoA brief search on Mouser seems to indicate that The AVR Xmega costs roughly 2.5 times as much as other 8 bit MCUs from Atmel with comparable amounts of flash/RAM -- are there other "selling point" on-chip perpiherals significantly contributing to that cost?
- fredoralive 4y agoGenerally a lot more stuff than the average AVR, so (IIRC) you have a multi level interrupt controller, a DMA unit, more adaptable clock / power configuration, and just more of things like UARTS and ADCs (which tended to have more features) and so on[1]. It feels more like an AVR core bolted onto something nearer to the “everything and a kitchen sink” peripheral set you get with a 32 bit ARM MCU. The projects I worked on weren’t particularly super cost sensitive though, so I’m perhaps a bit isolated from the “every cent matters” level. (Also, you’d probably just use one of those 32 bit ARM chips nowadays). [1] I don’t have an encyclopaedic knowledge of the AVR range and haven’t looked at in a couple of years, so I’m sure some of the advanced stuff is available on Mega models.
- ilyt 4y agocheapest one I found with AES is ~$1.5 https://eu.mouser.com/ProductDetail/STMicroelectronics/STM32L021D4P7DTR?qs=%252B6g0mu59x7LRqnyho9XTpA%3D%3D https://eu.mouser.com/ProductDetail/STMicroelectronics/STM32... There are probably even cheaper ones
- tptacek 4y agoThey're not just optimized to "fit" into small devices, but also for handling things like ultra-small messages, which is a common requirement in RF protocols.
- charcircuit 4y agoAES can handle ultra small messages just fine and a hash's security is based off of its length.
- tptacek 4y agoAES-what? AES is a block transform. Ascon is an AEAD construction.
- Avamander 4y agoYou can also get crypto coprocessors to accelerate such operations, without switching platforms or sacrificing for example power usage.