blog/data/2017-03-01-chaoskey.txt

   1 Title: Unlimited randomness with the ChaosKey?
   2 Tags: english, debian
   3 Date: 2017-03-01 20:50
   4
   5 <p>A few days ago I ordered a small batch of
   6 <a href="http://altusmetrum.org/ChaosKey/">the ChaosKey</a>, a small
   7 USB dongle for generating entropy created by Bdale Garbee and Keith
   8 Packard.  Yesterday it arrived, and I am very happy to report that it
   9 work great!  According to its designers, to get it to work out of the
  10 box, you need the Linux kernel version 4.1 or later.  I tested on a
  11 Debian Stretch machine (kernel version 4.9), and there it worked just
  12 fine, increasing the available entropy very quickly.  I wrote a small
  13 test oneliner to test.  It first print the current entropy level,
  14 drain /dev/random, and then print the entropy level for five seconds.
  15 Here is the situation without the ChaosKey inserted:</p>
  16
  17 <blockquote><pre>
  18 % cat /proc/sys/kernel/random/entropy_avail; \
  19   dd bs=1M if=/dev/random of=/dev/null count=1; \
  20   for n in $(seq 1 5); do \
  21      cat /proc/sys/kernel/random/entropy_avail; \
  22      sleep 1; \
  23   done
  24 300
  25 0+1 oppføringer inn
  26 0+1 oppføringer ut
  27 28 byte kopiert, 0,000264565 s, 106 kB/s
  28 4
  29 8
  30 12
  31 17
  32 21
  33 %
  34 </pre></blockquote>
  35
  36 <p>The entropy level increases by 3-4 every second.  In such case any
  37 application requiring random bits (like a HTTPS enabled web server)
  38 will halt and wait for more entrpy.  And here is the situation with
  39 the ChaosKey inserted:</p>
  40
  41 <blockquote><pre>
  42 % cat /proc/sys/kernel/random/entropy_avail; \
  43   dd bs=1M if=/dev/random of=/dev/null count=1; \
  44   for n in $(seq 1 5); do \
  45      cat /proc/sys/kernel/random/entropy_avail; \
  46      sleep 1; \
  47   done
  48 1079
  49 0+1 oppføringer inn
  50 0+1 oppføringer ut
  51 104 byte kopiert, 0,000487647 s, 213 kB/s
  52 433
  53 1028
  54 1031
  55 1035
  56 1038
  57 %
  58 </pre></blockquote>
  59
  60 <p>Quite the difference. :) I bought a few more than I need, in case
  61 someone want to buy one here in Norway. :)</p>