cvs commit: src/sys/kern kern_random.c

Matthew Dillon dillon at
Wed Apr 12 11:30:45 PDT 2006

dillon      2006/04/12 11:28:30 PDT

DragonFly src repository

  Modified files:
    sys/kern             kern_random.c 
  Note: the previous rev's CVS comment was messed up due to an editor snafu.
  /dev/random was almost always returning 0 bytes.  This was due to several
  factors, primarily the fact that the stack smash handler reads 32 bytes from
  /dev/urandom every time a program is exec'd, and because /dev/random and
  /dev/urandom share the same pool.
  * Give /dev/random and /dev/urandom their own separate pools.
  * Be slightly less conservative on the number of bits of randomness we
    think we've added.
  * extract_entropy() calls add_timer_randomness(), which adds entropy.  This
    can create a situation where entropy always appears to be available when,
    in fact, it is of very low quality.  Add a little hysteresis so degenerate
    cases return 0 bytes instead of 1 byte.
  * Also (in this commit) fix a bug in the previous commit where the randomness
    added was accidently halved.
  Reported-by: David Rhodus
  Revision  Changes    Path
  1.14      +11 -13    src/sys/kern/kern_random.c

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