Timings for random

[Gary E. Miller]

Yo Hal!

On Sun, 29 Jan 2017 17:15:05 -0800
Hal Murray <hmurray at megapathdsl.net> wrote:

> gem at rellim.com said:
> > You can't run out of randomness with RAND_bytes().  
> 
> Would you please say more.  The man page says:
> 
>        RAND_bytes() puts num cryptographically strong pseudo-random
> bytes into buf. An error occurs if the PRNG has not been seeded with
> enough randomness to ensure an unpredictable byte sequence.

Doesn't that say it?  Once seeded it does not run out.

> How can I be sure that it has "been seeded with enough"?

Use RAND_status() or RAND_event()

On Linux you can do:

    cat /proc/sys/kernel/random/entropy_avail

Most sources say entropy past 128 is good enough.

As a general rule, don't do important crypto things just after system
boot.  And be especially careful running in a VM.


RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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