I realized that we don't seem to be saving any of the entropy in the kernel's random pool [0] across reboots. This means that for some period after boot, /dev/urandom may not be safe to use. From random(4): --- If a seed file is saved across reboots as recommended below (all major Linux distributions have done this since 2000 at least), [/dev/urandom's] output is cryptographically secure against attackers without local root access as soon as it is reloaded in the boot sequence, and perfectly adequate for network encryption session keys. --- I interpret that text to mean that, without use of a seed file, urandom's output is *not* adequate for network encryption session keys (SSH, TLS, etc) until enough entropy has been gathered. I don't know how long that takes. I've attached my not-yet-working attempt at a urandom-seed-service. I tried to get it working on my own but I need the assistance of some more experienced Guix hackers :) I've also attached a stand-alone Guile script to illustrate what the effect of the service should be. This script does seem to work. I'm sure the use of shell tools could be replaced by Guile. After applying my patch and attempting `guix system vm ...`, I get the attached backtrace. Does anyone have advice about the service? Am I wrong that we need to seed /dev/urandom to make it work properly? [0] See the man page for random(4).
random.scm
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urandom-seed.patch
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backtrace
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