I've been wondering how and when OpenSSL decides whether it can use the
new aes instructions? Does it decide at build time or at run time?
If I build on a CPU that supports aes instructions but run on a cpu that
does not, will bad things happen? Or is OpenSSL smart enough to call
functions implemented without aes instructions in that case?
Norm Green
On 8/10/16 06:28, Jan Just Keijser wrote:
Hi,
On 10/08/16 14:25, Nagesh shamnur wrote:
Hi Group,
I am running an application which transfers huge chunks of data every
second (850Mbps) and the same is secured using openssl. However the
CPU usage on windows is very high ( ~ 100%). So as a part of the
analysis, I stumbled upon the information that, when using AES
encryption, if the underlying hardware is Intel CPU, it can support
AES-NI instruction set and hence make the crypto processing faster.
So, I wanted to confirm if the same is enabled in my hardware.
So, I wanted to know how to verify if the run is able to use the
AES-NI instruction set available in the hardware.
I have built openssl and have ensured enabling the asm in both linux
and windows build.
For windows, to confirm if AES-NI is enabled, support of tools
available like truecrypt, CPU-Z and blackbox were used if the same
was enabled in OS usage. And I found that the same is disabled. Also
I found in some blogs that the same needs to be enabled in BIOS. When
checked the BIOS settings, the option was not be found and a BIOS
update is required to enable the same.
However in linux I was unable to conclude if AES-NI is disabled since
I didn’t had access to any such tools on linux. I checked "#cpuinfo |
grep aes" and i was unable to find any line regarding AES-NI. However
when i run the ./openssl speed -evp aes-128-gcm and
OPENSSL_ia32cap="~0x200000200000000" ./openssl speed -elapsed -evp
aes-128-gcm i am able to find the difference in speed. So i wanted to
check how to confirm if my linux build has AES-NI enabled or not?
Environment Information:
CPU: E5-2620 0 @2.0GHz
OS: Windows Server 2008
Linux: Ubuntu 3.11.0-15-generic
Openssl versoin: 1.0.2h
I've got a server with that exact same CPU over here; with openssl
1.0.2d I see the following results:
$ ./openssl speed -evp aes-128-gcm
[...]
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192
bytes
aes-128-gcm 184391.41k 465791.06k 689190.61k .65k 781295.62k
$ OPENSSL_ia32cap=0 ./openssl speed -evp aes-128-gcm
[...]
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192
bytes
aes-128-gcm 43906.03k 49490.24k 51037.70k 51554.65k
51699.71k
i.e. with AES-NI disabled performance is about ~15 times less. On this
CPU turboboost is not working so your numbers maybe slightly different.
Another good way to test whether AES-NI is working is by comparing
BF-CBC to AES-256-CBC: without AES-NI, BF will be faster. with AES-NI,
AES will be faster.
HTH,
JJK
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