zephyr/drivers/entropy/Kconfig.rv32m1
Jordan Yates fdeaa9103e random: deprecate XOROSHIRO_RANDOM_GENERATOR
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>
2021-08-05 11:24:44 +02:00

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# RV32M1 entropy generator driver configuration
# Copyright 2019 NXP
# SPDX-License-Identifier: Apache-2.0
config ENTROPY_RV32M1_TRNG
bool "RV32M1 TRNG driver"
depends on SOC_OPENISA_RV32M1_RISCV32
select ENTROPY_HAS_DRIVER
help
This option enables the true random number generator (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 xoshiro RNG.
choice RNG_GENERATOR_CHOICE
default XOSHIRO_RANDOM_GENERATOR if ENTROPY_RV32M1_TRNG
endchoice