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

bugtracker-admin at leaf.dragonflybsd.org bugtracker-admin at leaf.dragonflybsd.org
Mon Jan 19 08:21:37 PST 2015

Issue #1689 has been updated by alexh.

Status changed from Feedback to Closed

robin.carey1 wrote:
> Dear Alex,
> You keep referring to it (i.e. /dev/random) as a "CSPRNG"; that is
> incorrect.
> CSPRNG is an abbreviation for Cryptographically Secure Pseudo Random Number
> Generator.
> What /dev/random should be is a CSRNG (Cryptographically Secure Random
> Number Generator) or CRNG (Cryptographic Random Number Generator).

Fortuna is a CSPRNG, which is what I'm referring to - its authors certainly say so :)

I'm not really going to be arguing with you about this. Whatever is implemented can stay implemented, and no, I'm not aware of every little bit that has or hasn't changed over the last 5 years.

I'm closing this.

Bug #1689: IBAA recommendation

* Author: robin.carey1
* Status: Closed
* 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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