src/sys/libkern/arc4random.c, branch releng/7.3

Lock down arc4random so it can be safely called w/o Giant.

2003-08-15T06:34:47+00:00

Minor code reorganization was required, but the only functional
change was that the first 1024 bytes of output are thrown out
after each reseed, rather than just the initial seed.

Use __FBSDID().

2003-06-11T05:37:42+00:00

Slight overhaul of arc4random() and friends.

2002-10-11T13:13:08+00:00

One bug fixed:  Use getmicrouptime() to trigger reseeds so that we
cannot be tricked by a clock being stepped backwards.

Express parameters in natural units and with natural names.

Don't use struct timeval more than we need to.

Various stylistic and readability polishing.

Introduce arc4rand(void *ptr, u_int len, int reseed) function which
returns a stream of pseudo-random bytes, observing the automatic
reseed criteria as well as allowing forced reseeds.

Rewrite arc4random() in terms of arc4rand().

Sponsored by:   DARPA & NAI Labs.

Fixed some typos, verboseness and misformatting in comments.

2001-08-30T12:30:58+00:00

Minor improvements to arc4random():

2001-08-30T01:15:25+00:00

- Decrease reseeding interval from every 64 to every 16384 runs
  to reduce entropy usage.
- Add time based reseeding.  (Every 5 minutes.)
- Throw away the first 256 words of output as suggested in
  "Weaknesses in the Key Scheduling Algorithm of RC4."

Reviewed by: Mark Murray
MFC After: jkh says ok

Recouple arc4random(9) to the entropy device. This works whether the

2000-12-02T16:23:54+00:00

entropy device is loaded or not.

If the entropy device is NOT loaded, the the quality of perturbations
supplied by this will suffer.

Back out previous revision now that sys/random.h is properly fixed.

2000-09-11T19:34:04+00:00

Add #include's of sys/proc.h and sys/param.h to silence a warning.

2000-09-11T05:51:58+00:00

Comment out unavailable call. This needs to be revisited when the entropy

2000-06-25T10:15:58+00:00

device is complete.
Reviewed by:	dfr

In the extremely miniscule chance that read_random returns <= 0, don't try

1999-11-29T19:23:35+00:00

and use that return code as a modulus (panics are bad, mmmkay?)