This is the much-discussed major upgrade to the random(4) device, known to you all as /dev/random.

This code has had an extensive rewrite and a good series of reviews, both by the author and other parties. This means a lot of code has been simplified. Pluggable structures for high-rate entropy generators are available, and it is most definitely not the case that /dev/random can be driven by only a hardware souce any more. This has been designed out of the device. Hardware sources are stirred into the CSPRNG (Yarrow, Fortuna) like any other entropy source. Pluggable modules may be written by third parties for additional sources.

The harvesting structures and consequently the locking have been simplified. Entropy harvesting is done in a more general way (the documentation for this will follow). There is some GREAT entropy to be had in the UMA allocator, but it is disabled for now as messing with that is likely to annoy many people.

The venerable (but effective) Yarrow algorithm, which is no longer supported by its authors now has an alternative, Fortuna. For now, Yarrow is retained as the default algorithm, but this may be changed using a kernel option. It is intended to make Fortuna the default algorithm for 11.0. Interested parties are encouraged to read ISBN 978-0-470-47424-2 "Cryptography Engineering" By Ferguson, Schneier and Kohno for Fortuna's gory details. Heck, read it anyway.

Many thanks to Arthur Mesh who did early grunt work, and who got caught in the crossfire rather more than he deserved to.

My thanks also to folks who helped me thresh this out on whiteboards and in the odd "Hallway track", or otherwise.

My Nomex pants are on. Let the feedback commence!

Reviewed by:	trasz,des(partial),imp(partial?),rwatson(partial?)
Approved by:	so(des)

3 files changed, 8 insertions, 10 deletions

diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index 4eb25d54f793..513300c57334 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -2993,10 +2993,10 @@ options 	BROOKTREE_ALLOC_PAGES=(217*4+1)
 options 	MAXFILES=999
 
 # Random number generator
-options 	RANDOM_YARROW	# Yarrow RNG
-##options 	RANDOM_FORTUNA	# Fortuna RNG - not yet implemented
+# Only ONE of the below two may be used; they are mutually exclusive.
+options 	RANDOM_YARROW	# Yarrow CSPRNG (Default)
+#options 	RANDOM_FORTUNA	# Fortuna CSPRNG
 options 	RANDOM_DEBUG	# Debugging messages
-options 	RANDOM_RWFILE	# Read and write entropy cache
 
 # Module to enable execution of application via emulators like QEMU
 options         IMAGACT_BINMISC
diff --git a/sys/conf/files b/sys/conf/files
index 3e89dbb18a97..7abcc6692ebf 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -2132,16 +2132,15 @@ rt2860.fw			optional rt2860fw | ralfw		\
 	compile-with	"${NORMAL_FW}"					\
 	no-obj no-implicit-rule						\
 	clean		"rt2860.fw"
-dev/random/harvest.c		standard
-dev/random/dummy_rng.c		standard
+dev/random/randomdev.c		standard
 dev/random/random_adaptors.c	standard
-dev/random/live_entropy_sources.c	optional random
-dev/random/random_harvestq.c	optional random
-dev/random/randomdev.c		optional random
+dev/random/dummy_rng.c		standard
+dev/random/live_entropy_sources.c	standard
+dev/random/random_harvestq.c	standard
 dev/random/randomdev_soft.c	optional random
 dev/random/yarrow.c		optional random
+dev/random/fortuna.c		optional random
 dev/random/hash.c		optional random
-dev/random/rwfile.c		optional random
 dev/rc/rc.c			optional rc
 dev/re/if_re.c			optional re
 dev/rl/if_rl.c			optional rl pci
diff --git a/sys/conf/options b/sys/conf/options
index f6ad35ac979c..ae0f852bfd6f 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -930,4 +930,3 @@ RCTL		opt_global.h
 RANDOM_YARROW	opt_random.h
 RANDOM_FORTUNA	opt_random.h
 RANDOM_DEBUG	opt_random.h
-RANDOM_RWFILE	opt_random.h