[openssl-users] OPENSSL_SYS_VOS meaning

[Wim Lewis]

On Aug 24, 2015, at 11:33 AM, David Luengo López <dluengo at rti.com> wrote:
> 439 #define DUMMY_SEED "...................." /* at least MD_DIGEST_LENGTH */
> 440             /* Note that the seed does not matter, it's just that
> 441              * ssleay_rand_add expects to have something to hash. */
> 442             ssleay_rand_add(DUMMY_SEED, MD_DIGEST_LENGTH, 0.0);
> 
> I don't know why the 0.0 parameter, since we are not adding anything here I never get more entropy in the pool. Any explanation for this 0.0?

Because there is actually no entropy in DUMMY_SEED --- it's a constant. This piece of code is "stirring" the pool; it doesn't increase the amount of entropy (unpredictability) in the pool, it just makes sure that all the bits of the pool are equally unpredictable. Actual entropy must be added by some other piece of code.

> Anyone knows what does OPENSSL_SYS_VOS macro means?

The notes from the patch from Paul Green adding randomness support for VOS might have useful information for you:
    https://rt.openssl.org/Ticket/Display.html?id=2563&user=guest&pass=guest

(I do not know enough about VxWorks or VOS to say whether defining OPENSSL_SYS_VOS safely solves your problem, though it seems plausible)