crypto: jitter - set default OSR to 3

commit 95a798d20060d2b648dd604321e347c85edfd783 upstream.

The user space Jitter RNG library uses the oversampling rate of 3 which
implies that each time stamp is credited with 1/3 bit of entropy. To
obtain 256 bits of entropy, 768 time stamps need to be sampled. The
increase in OSR is applied based on a report where the Jitter RNG is
used on a system exhibiting a challenging environment to collect
entropy.

This OSR default value is now applied to the Linux kernel version of
the Jitter RNG as well.

The increase in the OSR from 1 to 3 also implies that the Jitter RNG is
now slower by default.

Reported-by: Jeff Barnes <jeffbarnes@microsoft.com>
Signed-off-by: Stephan Mueller <smueller@chronox.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Huang Cun <cunhuang@tencent.com>
This commit is contained in:
Stephan Mueller 2024-08-12 08:25:42 +02:00 committed by Huang Cun
parent 00f5dc99fc
commit 0e53f6bb1e
1 changed files with 1 additions and 1 deletions

View File

@ -1343,7 +1343,7 @@ config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE
config CRYPTO_JITTERENTROPY_OSR config CRYPTO_JITTERENTROPY_OSR
int "CPU Jitter RNG Oversampling Rate" int "CPU Jitter RNG Oversampling Rate"
range 1 15 range 1 15
default 1 default 3
depends on CRYPTO_JITTERENTROPY depends on CRYPTO_JITTERENTROPY
help help
The Jitter RNG allows the specification of an oversampling rate (OSR). The Jitter RNG allows the specification of an oversampling rate (OSR).