crypto: exynos - Reseed PRNG after generating 2^16 random bytes

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Reseed PRNG after reading 65 kB of randomness. Although this may reduce
performance, in most cases the loss is not noticeable. Also the time
based threshold for reseeding is changed to one second. Reseeding is
performed whenever either limit is exceeded.

Reseeding of a PRNG does not increase entropy, but it helps preventing
backtracking the internal state of the device from its output sequence,
and hence, prevents potential attacker from predicting numbers to be
generated.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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Łukasz Stelmach 2017-12-12 17:36:06 +01:00 • committed by Herbert Xu

parent 3a5a5e5c07

commit 99c9acfe59

1 changed files with 11 additions and 4 deletions

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drivers/crypto/exynos-rng.c

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