michaelh/zephyr
1
0
Fork 0
Code Releases Activity

random: deprecate XOROSHIRO_RANDOM_GENERATOR

Browse source 
Deprecate the xoroshiro128+ PRNG algorithm in favour of xoshiro128++.
xoshiro128++ is a drop-in replacement which is invisible from the user
perspective.

xoroshiro128+ is unsuitable because it is explicitly a floating-point
PRNG, not a general-purpose PRNG. This means that the lower 4 bits of
the output are actually linear, not random (from the designers,
https://prng.di.unimi.it/). This means 1/8th of the generated data is
not random.

Additionally, xoroshiro128+ is not a 32bit algorithm, it operates on
64bit numbers. For the vast majority of Zephyr devices, this makes the
PRNG slower than it needs to be. The replacement (xoshiro128++) is
32bit, with no loss in state space (still 128 bit).

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
This commit is contained in:
Jordan Yates 2021-07-25 19:00:50 +10:00 • committed by Carles Cufí
commit fdeaa9103e
9 changed files with 15 additions and 149 deletions
Download patch file Download diff file Expand all files Collapse all files

4
drivers/entropy/Kconfig.rv32m1
View file

@ -12,7 +12,7 @@ config ENTROPY_RV32M1_TRNG
driver based on the RV32M1 TRNG driver.
# Don't use use the RV32M1 TRNG as a random source since it can be quite slow.
# Instead, use the software implemented xoroshiro RNG.
# Instead, use the software implemented xoshiro RNG.
choice RNG_GENERATOR_CHOICE
default XOROSHIRO_RANDOM_GENERATOR if ENTROPY_RV32M1_TRNG
default XOSHIRO_RANDOM_GENERATOR if ENTROPY_RV32M1_TRNG
endchoice