Searched hist:"2 a5e2ec6b9dad8006f75570fcf99073731919eeb" (Results 1 – 2 of 2) sorted by relevance
| /optee_os/core/include/tee/ |
| H A D | tee_cryp_utl.h | 2a5e2ec6b9dad8006f75570fcf99073731919eeb Thu Jan 26 13:37:10 UTC 2017 Andy Green <andy@warmcat.com> prng: move old implementation to be weak default
The patch replaces the original entropy scheme using system time with
the new api plat_prng_add_jitter_entropy().
The old scheme aimed to get 64 bits of entropy from the current time
expressed in 64 bits in ms each time. Most of this was in fact zeros or
unchanging for >256s. If you call it twice with 1ms, it actually
provides 0 bits of entropy.
The replacement scheme aims to get 2 bits of entropy from the counter,
which typically operates faster than 1MHz, greater than a thousand times
more precision than the old way, each time.
For backwards compatibility, the old scheme is retained as the default
or arches or platforms that did not provide an override to collect
jitter in a better way.
Signed-off-by: Andy Green <andy@warmcat.com>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org>
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| /optee_os/core/tee/ |
| H A D | tee_cryp_utl.c | 2a5e2ec6b9dad8006f75570fcf99073731919eeb Thu Jan 26 13:37:10 UTC 2017 Andy Green <andy@warmcat.com> prng: move old implementation to be weak default
The patch replaces the original entropy scheme using system time with
the new api plat_prng_add_jitter_entropy().
The old scheme aimed to get 64 bits of entropy from the current time
expressed in 64 bits in ms each time. Most of this was in fact zeros or
unchanging for >256s. If you call it twice with 1ms, it actually
provides 0 bits of entropy.
The replacement scheme aims to get 2 bits of entropy from the counter,
which typically operates faster than 1MHz, greater than a thousand times
more precision than the old way, each time.
For backwards compatibility, the old scheme is retained as the default
or arches or platforms that did not provide an override to collect
jitter in a better way.
Signed-off-by: Andy Green <andy@warmcat.com>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org>
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