I believe that secrets.token_bytes() and secrets.SystemRandom() should be changed even for 3.5.1 to use getrandom() on Linux. Thanks for fixing my spelling of the secrets API, Donald. :-) On Fri, Jun 10, 2016 at 12:17 PM, Donald Stufft <donald@stufft.io> wrote:
On Jun 10, 2016, at 3:05 PM, David Mertz <mertz@gnosis.cx> wrote:
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?
It feels to me like the correct spelling in 3.6 should probably be secrets.getrandom() or something related to that.
Well we have https://docs.python.org/dev/library/secrets.html#secrets.token_bytes so adding a getrandom() function to secrets would largely be the same as that function.
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.
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.
[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.
— Donald Stufft
-- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.