[DragonFlyBSD - Bug #1689] (Feedback) IBAA recommendation

bugtracker-admin at leaf.dragonflybsd.org bugtracker-admin at leaf.dragonflybsd.org
Mon Jan 19 05:59:59 PST 2015

Issue #1689 has been updated by tuxillo.

Description updated
Category set to Crypto
Status changed from New to Feedback
Assignee deleted (0)
Priority changed from Normal to Low
Target version set to 4.2.x

Hi Alex,

Any opinion on this one?

Antonio Huete

Bug #1689: IBAA recommendation

* Author: robin.carey1
* Status: Feedback
* Priority: Low
* Assignee: 
* Category: Crypto
* Target version: 4.2.x
Dear DragonFlyBSD bugs.

DragonFly uses Bob Jenkins' IBAA CSPRNG for /dev/random.

I have been doing some work on this CSPRNG, which is available from:


I have two recommendations to make with regard to the IBAA CSPRNG which is
used in DragonFly:

(1) Use my rounded up BETA=32/SHIFT=20 values as opposed to the original
SHIFT=19 value in the
original IBAA CSPRNG/algorithm (details available from above URL)


(2) Use a 32-bit counter. This is a minor modification, which gurantees no
bad states (an initial state of all zeroes
     maps back to an internal state of all zeroes after 256 iterations), and
also guarantees a cycle length of at least
     2^32. Details on how to implement the counter are available from the
above URL. It's a minor modification which
     has minimal performance impact.
Also, a 64-bit version of IBAA is available from the above URL. Matthew
Dillon seemed to be interested in that, with
regard to the 64-bit x86-64 port of DragonFly (but I haven't heard back from
him about that).

unnamed (1.4 KB)

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