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@xxxxxxxxxxxxx> Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxxx> --- crypto/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/crypto/Kconfig b/crypto/Kconfig index 72e2decb8c6a..a779cab668c2 100644 --- a/crypto/Kconfig +++ b/crypto/Kconfig @@ -1305,7 +1305,7 @@ config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE config CRYPTO_JITTERENTROPY_OSR int "CPU Jitter RNG Oversampling Rate" range 1 15 - default 1 + default 3 help The Jitter RNG allows the specification of an oversampling rate (OSR). The Jitter RNG operation requires a fixed amount of timing -- 2.46.0
