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)
As of r126744, we no longer feed the entropy device in jails upon
start, and collecting them is no longer useful.
PR: conf/126744
Submitted by: Eugene Grosbein <eugen grosbein net> (with minor changes)
MFC after: 1 week
Approved by: so (des)
all in one command, with no permissions race.
2. Simplify the rotation logic by cd'ing into the directory, with a test
to make sure that it succeeds.
3. Remove any files numbered higher than entropy_save_num. This helps when
the user reduces the number, and may be useful for other purposes down
the road.
4. Simplify the rotation logic by first testing the common case (it's a
regular file) then testing if something else exists with the same name
using elif. Also switch from using jot to simpler countdown format.
5. Fix logger lines and error messages to be more consistent, and wrap the
code more consistently in the 80 column range. The "not a regular file"
error message was mistakenly wrapped entirely in "quotes" which caused
logger to include line-wrapping whitespace. Change that to wrap only
the variables in quotes, which is both consistent and works better.
6. Update copyright to reflect the fact that changes were made this year.
Parts of 2-4 were taken from etc/periodic/daily/310.accounting
ignoring errors when sourcing rc.conf* files. The most common error
occurs when users put a command of some sort into those files.
(ifconfig is a popular choice)
2. Make the file rotation logic simpler by starting one down from
the "top" of the list, rather than at the top.
3. Try to make file rotation more secure by calling unlink(1) on all
new file names before rotating an old file to the new name, rather than
merely calling 'rm -f' on any files that exceed the number of files
to save.
rc.conf[.local]. Fix this, and leave the default as 2048.
Update the copyright year to include the present.
Update the assignment of the copyright to be me personally,
instead of "The FreeBSD Project" which is not a legal entity,
and therefore not a proper assignee. My intention remains the
same however, that this code continue to be BSD licensed, and
freely available to anyone that wants it under those terms.
PR: conf/75722
Submitted by: Nicolas Rachinsky <list@rachinsky.de>
it at boot time closer to the way we want it to be in the final version.
* Move the default directory to /var/db/entropy
* Run the entropy saving cron job every 11 minutes. This seems
to be a better default, although still bikeshed material.
* Feed /dev/random some cheesy "entropy" from various commands
and files before the disks are mounted. This gives /dev/random
a better chance of running without blocking early.
* Move the reseeding with previously stored entropy to the point
immediately after the disks are mounted.
* Make the harvesting script a little safer in regards to the
possibility of accidentally overwriting something other
than a regular file.
it can be used to reseed at boot time. This will greatly increase
the chances that there will be sufficient entropy available at
boot time to prevent long delays.
For /etc/rc, remove the vmstat and iostat runs from the attempt
to provide some cheesy randomness if the files fail, since
those programs are dynamically linked, and ldd seems to want
some randomness to do its magic.
Guidance and parameters for this project were provided by
Mark Murray, based on the requirements of the Yarrow
algorithm. Some helpful suggestions for implementation
(including the tip about iostat and vmstat) were provided
by Sheldon Hearn. All blame for problems or mistakes is
mine of course.
