Module Name: src
Committed By: riastradh
Date: Fri May 1 19:54:37 UTC 2020
Modified Files:
src/share/man/man4: rnd.4
Log Message:
Tighten language so it fits in one paragraph again.
This way the first two paragraphs have parallel structure:
- _Applications_ should read from /dev/urandom or sysctl kern.arandom...
- _Systems_ should be engineered to read once from /dev/random...
To generate a diff of this commit:
cvs rdiff -u -r1.31 -r1.32 src/share/man/man4/rnd.4
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man4/rnd.4
diff -u src/share/man/man4/rnd.4:1.31 src/share/man/man4/rnd.4:1.32
--- src/share/man/man4/rnd.4:1.31 Fri May 1 12:43:33 2020
+++ src/share/man/man4/rnd.4 Fri May 1 19:54:37 2020
@@ -1,4 +1,4 @@
-.\" $NetBSD: rnd.4,v 1.31 2020/05/01 12:43:33 nia Exp $
+.\" $NetBSD: rnd.4,v 1.32 2020/05/01 19:54:37 riastradh Exp $
.\"
.\" Copyright (c) 2014-2020 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -51,32 +51,28 @@ Will block early at boot if the system's
predictable.
.El
.Pp
-Applications can read from
-.Pa /dev/urandom
-when they need randomly generated data, e.g. key material for
-cryptography or seeds for simulations, and the device is known
-to be available.
-.Pp
-A
+Applications should read from
+.Pa /dev/urandom ,
+or the
.Xr sysctl 7
-variable,
+variable
.Li kern.arandom ,
-provides equivalent functionality to
-.Pa /dev/urandom
-and will never block. However, it only returns up to 256 bytes per call.
-This is expected to be enough for seeding most cryptographically secure
-random number generators and ciphers, and if more data is required the
-variable can be queried again.
-.Pp
-Applications should read from the sysctl variable when a high level of
-reliability is required, or the runtime environment cannot be predicted,
-e.g. in a library. It is possible that
+when they need randomly generated data, e.g. key material for
+cryptography or seeds for simulations.
+(The
+.Xr sysctl 7
+variable
+.Li kern.arandom
+is limited to 256 bytes per read, but is otherwise equivalent to
+reading from
.Pa /dev/urandom
-is unavailable due to the application being in a
+and always works even in a
.Xr chroot 8
-environment, or when other restrictions such as those enforced by
-.Xr setrlimit 2
-apply.
+environment without requiring a populated
+.Pa /dev
+tree and without opening a file descriptor, so
+.Li kern.arandom
+may be preferable to use in libraries.)
.Pp
Systems should be engineered to judiciously read at least once from
.Pa /dev/random
