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On 10.06.2016 21:17, Donald Stufft wrote:<br>
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<div class="">On Jun 10, 2016, at 3:05 PM, David Mertz <<a
moz-do-not-send="true" href="mailto:mertz@gnosis.cx"
class=""><a class="moz-txt-link-abbreviated" href="mailto:mertz@gnosis.cx">mertz@gnosis.cx</a></a>> wrote:</div>
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<div class=""><span style="font-family: Helvetica; font-size:
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font-weight: normal; letter-spacing: normal; orphans:
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none; white-space: normal; widows: auto; word-spacing:
0px; -webkit-text-stroke-width: 0px; float: none; display:
inline !important;" class="">OK. My understanding is that
Guido ruled out introducing an os.getrandom() API in
3.5.2. But would you be happy if that interface is added
to 3.6? </span>
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<div style="font-family: Helvetica; font-size: 12px;
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0px; -webkit-text-stroke-width: 0px;" class="">It feels to
me like the correct spelling in 3.6 should probably be
secrets.getrandom() or something related to that.</div>
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I am not a security expert but your reply makes it clear to me. So,
for me this makes:<br>
<br>
os -> os-dependent and because of this varies from os to os (also
quality-wise)<br>
random -> pseudo-random, but it works for most non-critical
use-cases<br>
secret -> that's for crypto<br>
<br>
<br>
If don't need crypto, secret would be a waste of resources, but if
you need crypto, then os and random are unsafe. I think that's
simple enough. At least, I would understand it.<br>
<br>
<br>
Just my 2 cents: if I need crypto, I would pay the price of blocking
rather then to get an exception (what are my alternatives? I need
those bits! ) or get unsecure bits.<br>
<br>
<br>
Sven<br>
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<blockquote
cite="mid:B50734BC-E2DC-4F7C-B607-A7D624A3C0C9@stufft.io"
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<div class="">Well we have <a moz-do-not-send="true"
href="https://docs.python.org/dev/library/secrets.html#secrets.token_bytes"
class="">https://docs.python.org/dev/library/secrets.html#secrets.token_bytes</a> so
adding a getrandom() function to secrets would largely be the
same as that function.</div>
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<div class="">The problem of course is that the secrets library in
3.6 uses os.urandom under the covers, so it’s security rests on
the security of os.urandom. To ensure that the secrets library
is actually safe even in early boot it’ll need to stop using
os.urandom on Linux and use the getrandom() function.</div>
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<div class="">That same library exposes random.SystemRandom as
secrets.SystemRandom [1], and of course SystemRandom uses
os.urandom too. So if we want people to treat
secrets.SystemRandom as “always secure” then it would need to
stop using os.urandom and start using the get random() function
on Linux as well.</div>
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<div class="">[1] This is actually documented as "using the
highest-quality sources provided by the operating system” in the
secrets documentation, and I’d argue that it is not using the
highest-quality source if it’s reading from /dev/urandom or
getrandom(GRD_NONBLOCK) on Linux systems where getrandom() is
available. Of course, it’s just an alias for
random.SystemRandom, and that is documented as using os.urandom.</div>
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—<br class="">
Donald Stufft<br class="">
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