[clug] command to reverse 'xxd -b'??

[Paul Warren]

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> 
> Someone wrote me reminding that Paul Wayper did a CLUG talk on
> Crypto or RNG's or something related not that long ago... Link &
> comments anyone? Don't want to reinvent the wheel :(
> 

I did the talk, well, presentation, on my work :)

I've written a simple C program that produces entropy from atmospheric
radio noise via an rtl-sdr dvb-t dongle:

https://github.com/pwarren/rtl-entropy

I used von-neumann debiasing, with code from:
http://openfortress.org/cryptodoc/random/noise-filter.c

One day, I'll get around to adding Kaminsky debiasing, and encryption,
which resists subtle attacks on the atmospheric radio noise by
unpredictably changing the output.

The cheap USB dongles can do about 3Mbits/s of entropy output from
atmospheric noise. If you put a 50 Ohm load on and put it in a tin
foil hat, you only get about 30kbit/s, tho that might be improved by
setting the gain values differently.

If someone wants to buy me a USRP, HackRF or BladeRF, I'll make my
program work with them, and we should be able to get more like 20 or
30 Mbit/s from the atmosphere :)

Cheers
- --
Paul Warren
https://pwarren.id.au
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