[openssl-dev] Adding async support

[Matt Caswell]

On 08/10/15 12:18, Dmitry Belyavsky wrote:
> 
> I see. So am I correct supposing that pseudo code for
> offload_cipher_to_hardware looks like this:
> 
> static int async_wrapper(void * args)
> {
> ...
> }
> 
> static ASYNC_JOB *offload (void *args)
> {
>   ASYNC_JOB *pjob = NULL;
>   int funcret;
>   size_t size = 0;
> 
>   int ret = ASYNC_start_job(&pjob, &funcret, async_wrapper, args, 
>                       *args, size);
>   if (ret != ASYNC_PAUSE) return NULL;
>   return pjob;
> }
> 
> ?

No. I think you are confusing two different things.

1) How does an *application* perform asynchronous work (via libssl or
libcrypto) using an asynchronous capable engine?

2) How does an asynchronous capable engine offload async work to its
hardware?

These patches solve the first problem only. It provides an API and
mechanism for control to pass between the application and engine and
back again (perhaps multiple times) during the invocation of a long
running crypto operation. It also provides some mechanisms to enable an
engine to signal the completion of work to the application.

The second problem is entirely engine dependant. It will be a different
solution for different hardware. These patches do not provide a solution
to that problem.

Matt