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Something that's puzzling me for a while is how we could calculate approximately the energy cost of using AES, for a company like Amazon or Google. How likely it is due to the nature of their business model that its an important part of their fixed cost? Considering key generation, encryption and decryption etc of so much data on a daily basis.

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  • $\begingroup$ If you really know what CPU and networking capabilities then you can model, otherwise this is an opinion-based question. $\endgroup$
    – kelalaka
    Mar 13 at 18:02
  • $\begingroup$ Yes indeed! Thank you for your input. Any case studies or research regarding this? That would be extremely helpful. I've been searching a lot but I'm still unable to find something useful. $\endgroup$ Mar 17 at 16:01

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Back of the envelope calculation:

According to the World Bank, 2020 internet traffic was 100,000 GB/s. According to this analysis, an Intel i5-8250U CPU uses 2.2 J/GB when using AES-NI to encrypt. Since traffic needs to be both encrypted and decrypted, let's double this to get an energy requirement of 4.4 J/GB.

This works out to approximately 14 terajoules of energy per year.

The US BLS says that February 2022 US electricity costs were $0.137 per kWh.

Therefore, if all internet traffic is encrypted with hardware similar to that referenced above, the total electricity cost to encrypt and decrypt all internet traffic for a year is approximately only $530,000.

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  • $\begingroup$ Hey! That's really helpful. I was wondering though. Can we really base the whole internet consumption based on an Intel i5-8250U CPU? I mean the average for 3 trillion GBs has to be more than 4.4J/GB right? Also the half-million $ electricity cost sounds a bit too small don't you think? $\endgroup$ Mar 17 at 15:57
  • $\begingroup$ @Tunnel_Vision on the one hand, not all encryption will use AES-NI and be power efficient, so it will be an underestimate. On the other hand, the calculation assumes that all traffic will be encrypted, causing an over-estimate. The AES paper says that "AES consumes between 20 to 30 joule per Gigabyte, AES-NI consumes between 2.2 to 2.7 joule per Gigabyte". I'd assume data centres almost exclusively use CPUs with AES acceleration. I was surprised too that the cost is so low, but I checked the math and I can't see a mistake. The conclusion is that AES is not power-hungry compared to other tasks. $\endgroup$
    – knaccc
    Mar 17 at 20:50
  • $\begingroup$ I see. Thank you very much. I agree with you on the math side. Now question is, who in the world would use AES without acceleration since it seems to be so slow and power-consuming. I wonder if our smartphones have that feature? $\endgroup$ Mar 18 at 14:31
  • $\begingroup$ @Tunnel_Vision not all CPUs have AES-NI. However, it's only slow in comparison, and is still not a huge burden. A 45W CPU running at full power will use 162,000 joules per hour, and if part of what it was doing was encrypting 10 GB in that hour (without AES-NI), that would only be 300 joules. $\endgroup$
    – knaccc
    Mar 18 at 15:12
  • $\begingroup$ Hey! I found this article: seagate.com/files/www-content/our-story/trends/files/… Essentially it says that the storage demands and generally the Global Datasphere would hit 175 Zettabytes by 2025. Would that give us any additional clues? Is traffic the only metric to calculate the energy cost? $\endgroup$ Mar 22 at 0:46

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