From 9a56cf2b5b4970843c215091ea9823a67e077310 Mon Sep 17 00:00:00 2001 From: Leo Famulari Date: Wed, 13 Dec 2017 18:49:28 -0500 Subject: services: urandom-seed: Try using a HWRNG to seed the Linux CRNG at boot. * gnu/services/base.scm (urandom-seed-shepherd-service): Try to read from '/dev/hwrng' at boot, as a supplement to any saved random seed. * doc/guix.texi (Base Services): Document the new feature. --- gnu/services/base.scm | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'gnu/services') diff --git a/gnu/services/base.scm b/gnu/services/base.scm index 5e08927af3..a3654fd4d3 100644 --- a/gnu/services/base.scm +++ b/gnu/services/base.scm @@ -516,6 +516,24 @@ (define (urandom-seed-shepherd-service _) (call-with-output-file "/dev/urandom" (lambda (urandom) (dump-port seed urandom)))))) + + ;; Try writing from /dev/hwrng into /dev/urandom. + ;; It seems that the file /dev/hwrng always exists, even + ;; when there is no hardware random number generator + ;; available. So, we handle a failed read or any other error + ;; reported by the operating system. + (let ((buf (catch 'system-error + (lambda () + (call-with-input-file "/dev/hwrng" + (lambda (hwrng) + (get-bytevector-n hwrng 512)))) + ;; Silence is golden... + (const #f)))) + (when buf + (call-with-output-file "/dev/urandom" + (lambda (urandom) + (put-bytevector urandom buf))))) + ;; Immediately refresh the seed in case the system doesn't ;; shut down cleanly. (call-with-input-file "/dev/urandom" -- cgit v1.2.3