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Comment by CHY872 | Hacker News Reader

I have no doubt that a few people will buy this device, but it costs $60. Add to an Arduino for like $20 and you're fast heading towards $100 for a device that can do very little. If your project is actually so complicated that you need strong crypto, why not just use a Raspberry Pi?

Power usage approaches Raspberry Pi anyway; the RTC in this device uses between 0.75 and 1W

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Really? 0.75-1W for an RTC that has a standby mode based on a coin cell? That sounds crazy! It's an SO8 package - can that even dissipate that much power?! Sounds double-crazy!!

Oh, wait, datasheet says its 0.0015mW max. https://cdn.sparkfun.com/datasheets/Dev/Beagle/DS3231M.pdf And 1 Watt would make the part run at 120˚C above ambient.

> Oh, wait, datasheet says its 0.0015mW max

I think you mean 1.5mW.

Whoops, thanks. I actually meant 0.0015 W to keep the units the same.

Ouch! Sorry for that blunder, of course I misread the datasheet...

Yeah it's totally unrealistic!

These are for learning and rapid prototyping. A raspberry pi hardly teaches anything about embedded systems compared to kits like this.

Yeah, but this doesn't teach you about cryptography except for using it (which you could do on the Pi) because it's a black box, so doesn't teach you any more about embedded systems than a normal Arduino and a few cheap extensions. I'm not knocking the Arduino - it's a fantastic bit of kit and I've had great fun with mine, but this is a very expensive learning experience for the amount that you can learn.

For rapid prototyping - the rapid prototyper shouldn't be dealing with cryptographic primitives full stop.

Folks making things like hardware Bitcoin wallets and such likely don't want an OS in the mix because of security considerations.

It's $60, but consider that as a cost not for a production device, but instead as a commercial development board, letting you get hands-on experience working with each of the chips on the board before you design them into a mass-production product.

While that's true, the chips aren't themselves cheap; together they cost £6.90 (if I read the pages right) if you're buying from digikey by the 500.

The bigger concern is what you're actually doing with the crypto. Almost every use for crypto is intrinsically linked to transmitting the encrypted data; the amount of work to do something nontrivial would be pretty mental.

Any commercial project would probably approach the problem at a higher level; i.e. you'd buy an ARM microcontroller and a TLS stack.

What hardware crypto does a Raspberry Pi have?

I don't know, but implementing AES, HMAC-SHA2, and GCM on an ARM seems a lot more sane than doing it on an AVR.

>more sane than doing it on an AVR.

Well, the point of using special-purpose chips like the ATAES132, which has a hardware implementation of AES, is so you wouldn't have to implement the algorithm in AVR.

I think you are entirely missing the point of these Atmel chips.

More generally (and this is not necessarily addressed to you specifically), I find the knee-jerk response of "just use a Raspberry Pi" amusing. I design embedded systems. Raspberry Pi is, at a first approximation, completely useless, for any task you might want to throw at it.

There are many reasons. Power consumption, complexity, failure rate, poor reliability, reliance on SD cards, poor SD card reliability, poor peripherals, poor documentation, I could go on. RPI has two things going for it: 1) the video processing peripherals, 2) publicity/popularity.

Now, when thinking about embedded systems, most of the time I won't even consider things the size of a Pi (or the much, much better BeagleBone Black). They are monsters, enormously complex and power-hungry beasts. What I will consider are MSP430s, STM32s, Kinetis K and L, and similar — so ARM Cortex M0, M0+ and M4 cores, running at about 50MHz, consuming around 60mW of power (about as much as an LED), and taking up about, say, 8mm2 of board space (that includes all necessary passives). These are well documented, have reasonable complexity, and can be programmed carefully to achieve excellent reliability.

These systems also need crypto, and by crypto I don't just mean "accelerated AES". The Atmel security line is not just "accelerators".

In other words, this board is a very interesting prototyping tool, and no, the answer to any problem is not "just use a Raspberry Pi".

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