[Arm-dev] Fwd: Re: Does openssl pick low level interface or high level interface to do encrypt?

Fri Aug 11 13:00:50 UTC 2017

Gordon, thanks for the response.

On 08/11/2017 08:42 AM, Gordan Bobic wrote:
> Most ARMs have hardware crypto.
>
> IIRC, aarch64 chips have AES inline instruction like modern x86 CPUs. 
> OpenSSL that ships with CentOS aarch64 already takes advantage of this.

Maybe when I retire (could be as early as start of '19, but by start of 
'21), I will move to aarch64 SoC.  :)

> On armv7hl and earlier, they typically come with an asynchronous 
> crypto coprocessor. What this does is allows the application to 
> provide a source data pointer, key, and target data pointer, and waits 
> for the co-processor to do it's thing.
> The upshot of this is what while the process is iowaiting for the 
> response, the kernel can schedule other things requiring CPU time to 
> run, so the main CPU can be productively busy while something else is 
> doing the crypto. On a Marvell Kirkwood, the crypto throughput of this 
> co-processor is approximately the same as what the main CPU can 
> produce, but does so while consuming less power and leaving the CPU 
> free to do other things, potentially doubling the throughput.
>
> To use this, you will need to:
>
> 1) build and install this kernel module:
> http://cryptodev-linux.org/
> 2) Recompile your openssl package with a modified ./configure line to 
> enable cryptodev offload

I would like to think this is in the C7-armv7hl we are working with...

> 3) Rebuild openssh package to back out RedHat's audit patch because it 
> breaks things horribly. IIRC (it's been a while since I worked on 
> this), RH's audit patch adds functionality to store the session crypto 
> keys used in the audit log for debugging. Unfortunately, once you have 
> passed the crypto keys to the crypto coprocessor, you cannot get to 
> them, so the code attempts the equivalent of use-after-free, which 
> (thankfully) fails and crashes sshd. In reality what you are much 
> better off doing is creating a SRPM of a clean vanilla latest upstream 
> openssh source and just using that, without any broken distro patches 
> getting in the way.

I don't care so much about SSH.  This is used occasionally for admin 
work.  https would be very frequent (and imaps, and ...).

>
>
>
> On Fri, Aug 11, 2017 at 1:08 PM, Robert Moskowitz <rgm at htt-consult.com 
> <mailto:rgm at htt-consult.com>> wrote:
>
>     How does OpenSSL work on ARM?
>
>     Do any arms have hardware crypto?
>
>     thanks
>
>
>     -------- Forwarded Message --------
>     Subject: 	Re: [openssl-users] Does openssl pick low level
>     interface or high level interface to do encrypt?
>     Date: 	Thu, 10 Aug 2017 15:16:09 +0000
>     From: 	Salz, Rich via openssl-users <openssl-users at openssl.org>
>     <mailto:openssl-users at openssl.org>
>     Reply-To: 	Salz, Rich <rsalz at akamai.com>
>     <mailto:rsalz at akamai.com>, openssl-users at openssl.org
>     <mailto:openssl-users at openssl.org>
>     To: 	openssl-users at openssl.org <mailto:openssl-users at openssl.org>
>     <openssl-users at openssl.org> <mailto:openssl-users at openssl.org>
>
>
>
>     What OpenSSL does is not necessarily obvious.  The INSTALL
>     document talks about the no-asm configuration option.  Details
>     about what the assembler code does in terms of optimization are
>     only available by reading the source code comments in the various
>     Perl files that generate the assembler, mostly.
>
>     On x86, the assembly code uses the CPUID instruction (see the
>     OPENSSL_ia32cap.pod manpage) to determine if various instructions
>     (AES, SSE, MMX, etc) are available and will use them if so.  For
>     other processors, similar tests are performed if at all possible.
>
>     I have added this to the FAQ
>
>     -- 
>
>     Senior Architect, Akamai Technologies
>
>     Member, OpenSSL Dev Team
>
>     IM: richsalz at jabber.at <mailto:richsalz at jabber.at> Twitter: RichSalz
>
>     *From:*- JinsongJi [mailto:jjsbear at hotmail.com]
>     *Sent:* Wednesday, August 09, 2017 9:09 AM
>     *To:* openssl-users at openssl.org <mailto:openssl-users at openssl.org>
>     *Subject:* [openssl-users] Does openssl pick low level interface
>     or high level interface to do encrypt?
>
>     Hi,
>
>     For one simple operation: openssl enc -aes-256-cbc -salt -in
>     foo.txt -out foo.enc
>
>     Does openssl pick classic implementation or AES-NI implementation
>     to do this encrypt?
>
>     Does any user/application always pick classic implementation
>     for AES operation regardless of AES-NI improves speed much?
>
>     Is there any document about this interface selection?
>
>     Thanks,
>
>     Jinsong
>
>
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>
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