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Can you expand on the CPUs that support 128 bit AES but not 256 bit? I didn't know that was a possibility.
by tedunangst 8y ago
Can you expand on the CPUs that support 128 bit AES but not 256 bit? I didn't know that was a possibility.
- CiPHPerCoder 8y agoHmm, no, I can't. This was something I had observed in practice over the years (i.e. several orders of magnitude performance difference between AES-128 and AES-256 from my PHP implementations), and "your CPU only supports AES-NI for 128-bit keys" was the explanation I was given at the time. I haven't observed this recently, and I'm on newer hardware, so the explanation made sense. In attempting to identify which CPUs were affected by this limitation, I've discovered that I was grossly misinformed about this. I'm going to update the article to redact this, ASAP. UPDATE: Redaction applied.
- simias 8y ago~10 years ago I had a small fanless computer running with an AMD Geode LX CPU that supported AES-128 but not 256 in hardware. https://en.wikipedia.org/wiki/Geode_(processor)#Geode_LX https://en.wikipedia.org/wiki/Geode_(processor)#Geode_LX
- tedunangst 8y agoIIRC the geode accelerator is more like a PCI device in the same SoC and not technically a CPU extension.
- dbuder 8y agoAnything below the desktop CPU, embedded stuff, 128 AES in hardware only just arrived on common mcus.