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crypto: jitter - set default OSR to 3

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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>
This commit is contained in:
Stephan Mueller 2024-08-12 08:25:42 +02:00 committed by Herbert Xu
parent 8e84a65007
commit 95a798d200
1 changed files with 1 additions and 1 deletions
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2
crypto/Kconfig
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@ -1305,7 +1305,7 @@ 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
help help
The Jitter RNG allows the specification of an oversampling rate (OSR). The Jitter RNG allows the specification of an oversampling rate (OSR).
The Jitter RNG operation requires a fixed amount of timing The Jitter RNG operation requires a fixed amount of timing