On Sep 27, 2016 10:33 AM, "Florian Weimer" <fw_at_deneb.enyo.de> wrote:
>
> * Daniel Stenberg:
>
> > On Tue, 27 Sep 2016, Florian Weimer wrote:
> >
> >>> I'm not sure this particular loop is as stupid as the comment
> >>> implies. RAND_bytes() is supposed to give crypto safe random and
> >>> according to https://wiki.openssl.org/index.php/Random_Numbers the
> >>> function will even init the random generator itself if it wasn't
> >>> done before.
> >>
> >> RAND_bytes can fail for various reasons, including if the generator
> >> could not be seeded. Details depend on the engine backend OpenSSL
> >> uses.
> >
> > Ah right, so the loop should check the return codes properly and be
> > able to return a failure back to its parent if they fail?
> >
> > Any chance (anyone of) you have a patch to suggest for this?
>
> Well, Török Edwin is right in the sense that modern OpenSSL should
> take care of this automatically. If there is still a platform where
> this is needed, we'd have to look at what it provides in terms of
> randomness sources, how we can properly synchronize access to the
> randomness file, and how we can prevent duplicate streams of random
> bytes reliably (which is difficult if there is no entropy source at
> all in the system).

Being devil's advocate, I think the level of responsibility, detail, cost
of errors for getting into random-management and cryptography may be so
high that it really should be left to alternative software libcurl consumes
(e.g. openssl), and should simply bail when it detects anomalies. Otherwise
we're getting into the mucky territory of monitoring/mitigating crypto.
Definitely something to think hard about before venturing in.

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Received on 2016-09-27