From 9949f5cb185a020d92cf6b8102edb73ec3a369eb Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Wed, 26 Nov 2014 23:58:29 +0100 Subject: [PATCH] random.4: Mention PRNG used by urandom /dev/urandom uses a pseudo-random number generator to replace missing entropy. Signed-off-by: Heinrich Schuchardt Signed-off-by: Michael Kerrisk --- man4/random.4 | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/man4/random.4 b/man4/random.4 index 44d9e34ef..1be19b881 100644 --- a/man4/random.4 +++ b/man4/random.4 @@ -63,8 +63,9 @@ will be set to .LP A read from the \fI/dev/urandom\fP device will not block waiting for more entropy. -As a result, if there is not sufficient entropy in the -entropy pool, the returned values are theoretically vulnerable to a +If there is not sufficient entropy, a pseudorandom number generator is used +to create the requested bytes. +As a result, in this case the returned values are theoretically vulnerable to a cryptographic attack on the algorithms used by the driver. Knowledge of how to do this is not available in the current unclassified literature, but it is theoretically possible that such an attack may