<div dir="ltr">Hello,<br><br><div>Sorry for awakening an old thread but it appears that miscellaneous changes to /dev/random or /dev/urandom during the last couple of years did not fundamentally fix what I noticed in 2019, supposing that this apparent weakness needed fixing.</div><div>(In summary, some WEAK results appeared very often on some specific tests with the /dev/urandom generator, while they never appeared with /dev/random, or very rarely)<br></div>The main change is that /dev/random is now "as weak" as /dev/urandom, probably because of this:<br><div><a href="https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.6-Random-Rework">https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.6-Random-Rework</a></div><div><br></div><div>Considering that the old /dev/random or other PRNG do not exhibit this behaviour, I suspect some kind of weakness here. I still could not find any explanation.<br></div><div><br></div><span style="font-family:monospace">$ dieharder -a -g 500<br>#=============================================================================#<br>#            dieharder version 3.31.1 Copyright 2003 Robert G. Brown          #<br>#=============================================================================#<br>   rng_name    |rands/second|   Seed   |<br>    /dev/random|  1.47e+07  |  97623993|<br>#=============================================================================#<br>        test_name   |ntup| tsamples |psamples|  p-value |Assessment<br>#=============================================================================#<br></span><div><span style="font-family:monospace">   diehard_birthdays|   0|       100|     100|0.98853103|  PASSED  <br></span></div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">          sts_serial|  10|    100000|     100|0.83110218|  PASSED  <br>          sts_serial|  10|    100000|     100|0.99559169|   WEAK   <-------------- here<br>          sts_serial|  11|    100000|     100|0.98425140|  PASSED  <br></span></div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">          sts_serial|  15|    100000|     100|0.99501524|   WEAK   <br></span></div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">      rgb_lagged_sum|  14|   1000000|     100|0.47229376|  PASSED  <br>      rgb_lagged_sum|  15|   1000000|     100|0.99950974|   WEAK   <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">Preparing to run test 209.  ntuple = 0<br>        dab_monobit2|  12|  65000000|       1|0.25934883|  PASSED  <br></span></div><div><span style="font-family:monospace"></span></div><div><span style="font-family:monospace">$ dieharder -a -g 501 <br>#=============================================================================#<br>#            dieharder version 3.31.1 Copyright 2003 Robert G. Brown          #<br>#=============================================================================#<br>   rng_name    |rands/second|   Seed   |<br>   /dev/urandom|  7.84e+06  |3770177091|<br>#=============================================================================#<br>        test_name   |ntup| tsamples |psamples|  p-value |Assessment<br>#=============================================================================#<br>   diehard_birthdays|   0|       100|     100|0.48144031|  PASSED  <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">        diehard_sums|   0|       100|     100|0.00896211|  PASSED  <br>        diehard_runs|   0|    100000|     100|0.00135805|   WEAK   <br>        diehard_runs|   0|    100000|     100|0.32971394|  PASSED  <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">        diehard_runs|   0|    100000|     100|0.00135805|   WEAK   <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">          sts_serial|   3|    100000|     100|0.00381696|   WEAK   <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">          sts_serial|  13|    100000|     100|0.99985868|   WEAK   <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">      rgb_lagged_sum|  22|   1000000|     100|0.00401025|   WEAK   <br></span></div><div><div><span style="font-family:monospace">[snip]</span></div><div><span style="font-family:monospace">$ <br></span></div><div><span style="font-family:monospace"><br></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><span style="font-family:monospace"></span></div><div></div></div>