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Additional Testing Of The rtl-sdr Dongle As A HWRNG

A couple days ago, I put up a post about using the Realtek SDR dongles as a hardware true random number generator. I only tested the randomness of a 512 MB file. I thought this time, I would but a bit more stock into it. In this case, I let it run for a while, until it was 1.8 GB in size. Interestingly enough, it stopped getting bigger after that point. Not sure why. However, I ran more tests on that 1.8 GB file. Creating this file took its time:

$ tail -f /run/rtl_entropy.fifo | dd of=random.img iflag=fullblock
3554130+0 records in
3554130+0 records out
1819714560 bytes (1.8 GB) copied, 3897.22 s, 467 kB/s

This filled up a bit faster than I had previously tested, going at a clip of about 3.826 Mbps.

Now it was time for the testing:

$ ent random.img
Entropy = 8.000000 bits per byte.

Optimum compression would reduce the size
of this 1819714560 byte file by 0 percent.

Chi square distribution for 1819714560 samples is 246.86, and randomly
would exceed this value 63.11 percent of the times.

Arithmetic mean value of data bytes is 127.4990 (127.5 = random).
Monte Carlo value for Pi is 3.141611317 (error 0.00 percent).
Serial correlation coefficient is 0.000013 (totally uncorrelated = 0.0).

It passes with flying colors on entropy estimation, compression, chi-square distributions, arithmetic mean, the Monte Carlo estimation for Pi, and serial correlation. Testing further, I ran it through the FIPS 140-2 tests:

$ rngtest < random.img
rngtest 2-unofficial-mt.14
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

rngtest: starting FIPS tests...
rngtest: entropy source exhausted!
rngtest: bits received from input: 14557716480
rngtest: FIPS 140-2 successes: 727288
rngtest: FIPS 140-2 failures: 597
rngtest: FIPS 140-2(2001-10-10) Monobit: 99
rngtest: FIPS 140-2(2001-10-10) Poker: 57
rngtest: FIPS 140-2(2001-10-10) Runs: 210
rngtest: FIPS 140-2(2001-10-10) Long run: 233
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=114.212; avg=6626.942; max=9536.743)Mibits/s
rngtest: FIPS tests speed: (min=61.133; avg=147.877; max=151.377)Mibits/s
rngtest: Program run time: 96034230 microseconds
You have new mail.
$ echo $?
1

Finally, the beast of beasts, I ran it through every Dieharder test. This took some time to complete. Here is a listing of the tests that it went through:

$ dieharder -l
#=============================================================================#
#            dieharder version 3.31.1 Copyright 2003 Robert G. Brown          #
#=============================================================================#
Installed dieharder tests:
 Test Number	                     Test Name	              Test Reliability
===============================================================================
  -d 0  	                  Diehard Birthdays Test	      Good
  -d 1  	                     Diehard OPERM5 Test	      Good
  -d 2  	          Diehard 32x32 Binary Rank Test	      Good
  -d 3  	            Diehard 6x8 Binary Rank Test	      Good
  -d 4  	                  Diehard Bitstream Test	      Good
  -d 5  	                            Diehard OPSO	   Suspect
  -d 6  	                       Diehard OQSO Test	   Suspect
  -d 7  	                        Diehard DNA Test	   Suspect
  -d 8  	      Diehard Count the 1s (stream) Test	      Good
  -d 9  	        Diehard Count the 1s Test (byte)	      Good
  -d 10  	                Diehard Parking Lot Test	      Good
  -d 11  	Diehard Minimum Distance (2d Circle) Test	      Good
  -d 12  	Diehard 3d Sphere (Minimum Distance) Test	      Good
  -d 13  	                    Diehard Squeeze Test	      Good
  -d 14  	                       Diehard Sums Test	Do Not Use
  -d 15  	                       Diehard Runs Test	      Good
  -d 16  	                      Diehard Craps Test	      Good
  -d 17  	            Marsaglia and Tsang GCD Test	      Good
  -d 100  	                        STS Monobit Test	      Good
  -d 101  	                           STS Runs Test	      Good
  -d 102  	           STS Serial Test (Generalized)	      Good
  -d 200  	               RGB Bit Distribution Test	      Good
  -d 201  	   RGB Generalized Minimum Distance Test	      Good
  -d 202  	                   RGB Permutations Test	      Good
  -d 203  	                     RGB Lagged Sum Test	      Good
  -d 204  	        RGB Kolmogorov-Smirnov Test Test	      Good
  -d 205  	                       Byte Distribution	      Good
  -d 206  	                                 DAB DCT	      Good
  -d 207  	                      DAB Fill Tree Test	      Good
  -d 208  	                    DAB Fill Tree 2 Test	      Good
  -d 209  	                      DAB Monobit 2 Test	      Good

So here are the results:

 $ dieharder -a < random.img
#=============================================================================#
#            dieharder version 3.31.1 Copyright 2003 Robert G. Brown          #
#=============================================================================#
   rng_name    |rands/second|   Seed   |
        mt19937|  1.25e+08  | 169223456|
#=============================================================================#
        test_name   |ntup| tsamples |psamples|  p-value |Assessment
#=============================================================================#
   diehard_birthdays|   0|       100|     100|0.91937112|  PASSED  
      diehard_operm5|   0|   1000000|     100|0.77213572|  PASSED  
  diehard_rank_32x32|   0|     40000|     100|0.04709503|  PASSED  
    diehard_rank_6x8|   0|    100000|     100|0.93031877|  PASSED  
   diehard_bitstream|   0|   2097152|     100|0.12183977|  PASSED  
        diehard_opso|   0|   2097152|     100|0.96023625|  PASSED  
        diehard_oqso|   0|   2097152|     100|0.61237304|  PASSED  
         diehard_dna|   0|   2097152|     100|0.66045974|  PASSED  
diehard_count_1s_str|   0|    256000|     100|0.16999968|  PASSED  
diehard_count_1s_byt|   0|    256000|     100|0.00992823|  PASSED  
 diehard_parking_lot|   0|     12000|     100|0.69592283|  PASSED  
    diehard_2dsphere|   2|      8000|     100|0.95358410|  PASSED  
    diehard_3dsphere|   3|      4000|     100|0.89028448|  PASSED  
     diehard_squeeze|   0|    100000|     100|0.81631204|  PASSED  
        diehard_sums|   0|       100|     100|0.03559934|  PASSED  
        diehard_runs|   0|    100000|     100|0.75027140|  PASSED  
        diehard_runs|   0|    100000|     100|0.43076351|  PASSED  
       diehard_craps|   0|    200000|     100|0.57749359|  PASSED  
       diehard_craps|   0|    200000|     100|0.00599436|  PASSED  
 marsaglia_tsang_gcd|   0|  10000000|     100|0.60121369|  PASSED  
 marsaglia_tsang_gcd|   0|  10000000|     100|0.04254338|  PASSED  
         sts_monobit|   1|    100000|     100|0.94352358|  PASSED  
            sts_runs|   2|    100000|     100|0.77549833|  PASSED  
          sts_serial|   1|    100000|     100|0.46198961|  PASSED  
          sts_serial|   2|    100000|     100|0.46002706|  PASSED  
          sts_serial|   3|    100000|     100|0.73076110|  PASSED  
          sts_serial|   3|    100000|     100|0.90967100|  PASSED  
          sts_serial|   4|    100000|     100|0.32002297|  PASSED  
          sts_serial|   4|    100000|     100|0.07478887|  PASSED  
          sts_serial|   5|    100000|     100|0.27486408|  PASSED  
          sts_serial|   5|    100000|     100|0.57409336|  PASSED  
          sts_serial|   6|    100000|     100|0.05095556|  PASSED  
          sts_serial|   6|    100000|     100|0.06341272|  PASSED  
          sts_serial|   7|    100000|     100|0.00941089|  PASSED  
          sts_serial|   7|    100000|     100|0.53679805|  PASSED  
          sts_serial|   8|    100000|     100|0.00122125|   WEAK   
          sts_serial|   8|    100000|     100|0.16239101|  PASSED  
          sts_serial|   9|    100000|     100|0.24007712|  PASSED  
          sts_serial|   9|    100000|     100|0.02659941|  PASSED  
          sts_serial|  10|    100000|     100|0.64616186|  PASSED  
          sts_serial|  10|    100000|     100|0.78783799|  PASSED  
          sts_serial|  11|    100000|     100|0.77618602|  PASSED  
          sts_serial|  11|    100000|     100|0.33875893|  PASSED  
          sts_serial|  12|    100000|     100|0.50423715|  PASSED  
          sts_serial|  12|    100000|     100|0.77528158|  PASSED  
          sts_serial|  13|    100000|     100|0.57625144|  PASSED  
          sts_serial|  13|    100000|     100|0.73422196|  PASSED  
          sts_serial|  14|    100000|     100|0.40891605|  PASSED  
          sts_serial|  14|    100000|     100|0.48542772|  PASSED  
          sts_serial|  15|    100000|     100|0.67319390|  PASSED  
          sts_serial|  15|    100000|     100|0.74730027|  PASSED  
          sts_serial|  16|    100000|     100|0.67519158|  PASSED  
          sts_serial|  16|    100000|     100|0.73171087|  PASSED  
         rgb_bitdist|   1|    100000|     100|0.87216594|  PASSED  
         rgb_bitdist|   2|    100000|     100|0.18831902|  PASSED  
         rgb_bitdist|   3|    100000|     100|0.16757216|  PASSED  
         rgb_bitdist|   4|    100000|     100|0.05327115|  PASSED  
         rgb_bitdist|   5|    100000|     100|0.75278396|  PASSED  
         rgb_bitdist|   6|    100000|     100|0.64749144|  PASSED  
         rgb_bitdist|   7|    100000|     100|0.20311557|  PASSED  
         rgb_bitdist|   8|    100000|     100|0.39994123|  PASSED  
         rgb_bitdist|   9|    100000|     100|0.52805289|  PASSED  
         rgb_bitdist|  10|    100000|     100|0.96091722|  PASSED  
         rgb_bitdist|  11|    100000|     100|0.97794399|  PASSED  
         rgb_bitdist|  12|    100000|     100|0.75009561|  PASSED  
rgb_minimum_distance|   2|     10000|    1000|0.58923867|  PASSED  
rgb_minimum_distance|   3|     10000|    1000|0.54294743|  PASSED  
rgb_minimum_distance|   4|     10000|    1000|0.59446131|  PASSED  
rgb_minimum_distance|   5|     10000|    1000|0.00047025|   WEAK   
    rgb_permutations|   2|    100000|     100|0.89040191|  PASSED  
    rgb_permutations|   3|    100000|     100|0.47917416|  PASSED  
    rgb_permutations|   4|    100000|     100|0.30964668|  PASSED  
    rgb_permutations|   5|    100000|     100|0.70217495|  PASSED  
      rgb_lagged_sum|   0|   1000000|     100|0.12796648|  PASSED  
      rgb_lagged_sum|   1|   1000000|     100|0.15077254|  PASSED  
      rgb_lagged_sum|   2|   1000000|     100|0.31141471|  PASSED  
      rgb_lagged_sum|   3|   1000000|     100|0.94974697|  PASSED  
      rgb_lagged_sum|   4|   1000000|     100|0.99256987|  PASSED  
      rgb_lagged_sum|   5|   1000000|     100|0.67854004|  PASSED  
      rgb_lagged_sum|   6|   1000000|     100|0.08600877|  PASSED  
      rgb_lagged_sum|   7|   1000000|     100|0.91633363|  PASSED  
      rgb_lagged_sum|   8|   1000000|     100|0.06794590|  PASSED  
      rgb_lagged_sum|   9|   1000000|     100|0.59024027|  PASSED  
      rgb_lagged_sum|  10|   1000000|     100|0.59285975|  PASSED  
      rgb_lagged_sum|  11|   1000000|     100|0.87178336|  PASSED  
      rgb_lagged_sum|  12|   1000000|     100|0.63401541|  PASSED  
      rgb_lagged_sum|  13|   1000000|     100|0.47202172|  PASSED  
      rgb_lagged_sum|  14|   1000000|     100|0.34616699|  PASSED  
      rgb_lagged_sum|  15|   1000000|     100|0.97221211|  PASSED  
      rgb_lagged_sum|  16|   1000000|     100|0.95576739|  PASSED  
      rgb_lagged_sum|  17|   1000000|     100|0.32367098|  PASSED  
      rgb_lagged_sum|  18|   1000000|     100|0.92792046|  PASSED  
      rgb_lagged_sum|  19|   1000000|     100|0.58128429|  PASSED  
      rgb_lagged_sum|  20|   1000000|     100|0.78197001|  PASSED  
      rgb_lagged_sum|  21|   1000000|     100|0.86068846|  PASSED  
      rgb_lagged_sum|  22|   1000000|     100|0.22496908|  PASSED  
      rgb_lagged_sum|  23|   1000000|     100|0.52387665|  PASSED  
      rgb_lagged_sum|  24|   1000000|     100|0.52748770|  PASSED  
      rgb_lagged_sum|  25|   1000000|     100|0.96442902|  PASSED  
      rgb_lagged_sum|  26|   1000000|     100|0.51298847|  PASSED  
      rgb_lagged_sum|  27|   1000000|     100|0.99123470|  PASSED  
      rgb_lagged_sum|  28|   1000000|     100|0.69774674|  PASSED  
      rgb_lagged_sum|  29|   1000000|     100|0.83646714|  PASSED  
      rgb_lagged_sum|  30|   1000000|     100|0.98573851|  PASSED  
      rgb_lagged_sum|  31|   1000000|     100|0.23580471|  PASSED  
      rgb_lagged_sum|  32|   1000000|     100|0.19150884|  PASSED  
     rgb_kstest_test|   0|     10000|    1000|0.67771558|  PASSED  
     dab_bytedistrib|   0|  51200000|       1|0.07152541|  PASSED  
             dab_dct| 256|     50000|       1|0.53841656|  PASSED  
Preparing to run test 207.  ntuple = 0
        dab_filltree|  32|  15000000|       1|0.09092747|  PASSED  
        dab_filltree|  32|  15000000|       1|0.83382174|  PASSED  
Preparing to run test 208.  ntuple = 0
       dab_filltree2|   0|   5000000|       1|0.37363586|  PASSED  
       dab_filltree2|   1|   5000000|       1|0.26890999|  PASSED  
Preparing to run test 209.  ntuple = 0
        dab_monobit2|  12|  65000000|       1|0.80810458|  PASSED  

I don't have an image to look at to visually verify that there are no obvious patterns. At 1.8 GB, I feel that it would be just a bit too unwieldy anyway. So, I'll need to trust the previous tests for randomness that the data really is random. After these 3 series of tests, I can only conclude that using a Realtek SDR as a HWRNG will generate as "true random" data as you can hope for.

{ 2 } Comments

  1. Jordi C | January 13, 2016 at 4:29 am | Permalink

    Just to point out that the tests with Dieharder do not seem to be correct. Instead of testing the random data you have in your file, you are testing the random data produced by the default pseudo-random generator. The PRNG 201 or 202 must be used together with the modifier "-f" to indicate the file.

  2. ghfhgfhg | January 26, 2016 at 4:27 pm | Permalink

    As the guy above said, you were not actually testing the radio trng. You were testing the default PRNG.

    You need to either use -g 201 with -f file or use -g 200 with pipes.

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