Symmetric cryptography with 8-bit microcontroller

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I need to use symmetric authentication encryption (AES-GCM or AES-CCM probably) in my project and was wondering whether it would be best to use a crypto-specific chip (like the ATAES132A) for this or implement the encryption in software on my ATMEGA328p microcontroller. I would like to know what the advantages are of using one over the other? What is usually done when using symmetric crypto on an 8-bit microcontroller? Will AES be too slow to run on an 8-bit uC at 1MHz? It seems to me that it would be simpler to user the ATAES132A but does this have any downsides?

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Crypto algos can take a lot of time to run on CPUs that are just doing 8bit integer maths so you may want to look at a switch from 328 to an Xmega - some (all?) of them have AES in silicon.

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Atmel have some app notes for doing AES encrypt/decrypt in software. Obviously having specific hardware to do this is faster, but how fast do you require? The app notes should have some benchmarks so you can determine if they will be fast enough.

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Nimyz wrote:
... (like the ATAES132A) ...
That's mentioned in this post from Atmel's blog :

Atmel

Bits & Pieces from the Embedded Design World

The CryptoShield is a dedicated security peripheral for the Arduino

http://blog.atmel.com/2015/04/24/the-cryptoshield-is-a-dedicated-security-peripheral-for-the-arduino/

"Dare to be naïve." - Buckminster Fuller