**Pingsweeps go BOING**

Fascinated by the Auralizer, I started my own, simplified
version, Netsound. The idea is to define
sound events to be triggered by network events. In netsound, you can
set `pcap(3)`

filters together with bounds and the sound
to play if the event occured that often. E.g.:
filter: icmp and not src net 131.188
max: 10
soundfile: sounds/boing.au

You can define many of these events. Netsound uses `libesd`

to play and mix the sounds.

*[/projects]
permanent link*

**Seltene Bäume in Erlangen**

- Ohmplatz, vor dem Simon-Ohm-Gymnasium: Sophora japonica.
- Bot. Garten, an der Mauer Richtung Bettenhaus: Kaukasische
Flügelnuss.
- Schlossgarten, nähe Ausgang Krankenhausstrasse:
Kanadischer Tulpenbaum.
- Fuss/Radweg hinter der Kopfklinik, an der Abzweigung zur
Schwabach runter: Ailanthus altissima
- In einem Garten in der Jordanstrasse: Kanadischer Tulpenbaum
- In der Hindenburgstrasse 80:
kastanienblättrige Eiche
- Wilhelminenstrasse: echte Akazien

*[/bäume]
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**Blum-Blum-Shubb-Niggurath**

The Blum-Blum-Shub Pseudo Random Number Generator works basically as follows:
- Setup
- Generate two large primes such that they both equal 3 mod 4
- Take the product N and forget the primes
- Fetch an initial state x_0 from a true RNG

- Operation per step
- compute next state: x_{i+1} = x_i^2 mod N
- output the least significant bit of x_{i+1}

Blum, Blum and Shub show that predicting the next bit from
the observed output is as hard as factoring N. In addition,
after erasing the primes computing previous states from the current one
is as hard as factorization.

A problem exists with the
expected cycle length of the produced random bits. As
Terry Ritter pointed out, maximum cycles (near the size of N)
can be assured by choosing the primes as “double--Germain”,
i.e. p = p'*2 + 1, p' = p''*2 + 1, with p, p', p'' all prime.

My implementation generates
such primes. A possible application for BBS is generating
strong randomness on embedded devices without physical sources
of randomness. Upon initialization,
a truely random seed could be stored on the device, which later is
updated synchronously after each step of the algorithm.

*[/projects]
permanent link*