In another question, Thomas' answer mentioned the AES-NI instruction set, which piqued my curiosity.

Is there a tool or process available out there to check whether the instruction set is available (besides comparing CPU model numbers)?


On Linux systems, do:

grep flags /proc/cpuinfo

This will give, for each CPU core, the list of what that core can do. The AES-NI instructions are there when the flag "aes" appears in the list of flags. See this page for a list of possible flag values.

On macOS, do:

sysctl -n machdep.cpu | grep -i aes

If it doesn't find anything, this machine doesn't have AES-NI.

For Windows, see this question on SuperUser.

  • THe aes flag only says when you have AES right? Not AES-NI (New instruction set)... – danger89 Sep 28 '20 at 20:57
  • Wrong, see my answer below. – danger89 Sep 28 '20 at 21:49

I'm not a low level hardware person any more, but an example from this post regarding a FreeBSD implemention shows you can grab info from Features2:

  • You should add how to get this output. e.g. dmesg | grep Features2 . – Matthias Weiler May 3 '17 at 15:45

On Windows systems, you can use free console tool "Coreinfo" from Sysinternals


There's also the cpuid utility available on a number of OS's (including FreeBSD, Linux, macOS, and NetBSD).

cpuid | grep -i aes
  AES instruction                         = true
  • On macOS, sysctl -n machdep.cpu | grep -i aes – dchest Jun 3 '17 at 14:58
  • @dchest - that's more of an answer to the original question than a comment about the cpuid answer. But FWIW, it does look like MacPorts has cpuid. – Juan Jun 6 '17 at 20:37
  • agreed, added to the accepted reply. – dchest Jun 7 '17 at 9:57

Since the question is about the NI (New Instruction) set for AES, NI accelerates the the AES algorithm.

A right answer could be (also according to Intel docs):

cpuid | grep -i aes | sort | uniq

If you want to be sure, you can also try the following command:

sort -u /proc/crypto | grep module

This really gives the kernel modules that are loaded, which should be aesni_intel (together with aes_x86_64), to be sure you are using the full Intel AES-NI support.

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