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Bug 1689946 - [RFE] Allow to use getrandom() instead of /dev/urandom or /dev/random as rng-random
Summary: [RFE] Allow to use getrandom() instead of /dev/urandom or /dev/random as rng-...
Status: NEW
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: qemu-kvm
Version: ---
Hardware: Unspecified
OS: Unspecified
Target Milestone: rc
: 8.0
Assignee: Hai Huang
QA Contact: Chao Yang
Depends On:
TreeView+ depends on / blocked
Reported: 2019-03-18 13:55 UTC by Attila Fazekas
Modified: 2019-03-20 12:16 UTC (History)
6 users (show)

Fixed In Version:
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Type: Bug
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Description Attila Fazekas 2019-03-18 13:55:07 UTC
Description of problem:
Please close this bug if I am wrong or it is no longer true.

- /dev/random  uses too many entropy and blocks
- /dev/urandom does not really consumes the entropy, but does not even blocks
   when the entropy pool is too low for crypto

getrandom()  works like urandom after enough entropy collected, but it blocks until a certain amount of entropy not acquired.

The getrandom() is fast and secure for 99.99999999% of the cases.

Practically, the /dev/urandom might be good enough,
but only getrandom(2) has some short of guarantee for minimum entropy.

Typically there is not much difference between getrandom() and urandom long time after the system booted,
but a guest might be started at early boot time,
where /dev/urandom usage can be bad.

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