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Use RDRAND to initialize blk_shred

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Mix jitterentropy with RDRAND when initializing psuedo-random number
generator.
This commit is contained in:
Emery Hemingway
2019-03-31 14:38:06 +02:00
parent a9617304f8
commit 61ee28cb7d
1 changed files with 19 additions and 1 deletions
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20
src/app/blk_shred/main.cc
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@@ -26,6 +26,9 @@
/* Jitterentropy includes */
#include <jitterentropy.h>
/* RDRAND utility */
#include <world/rdrand.h>
/* PCG includes */
#include <pcg_variants.h>
@@ -80,7 +83,22 @@ struct Blk_shred::Main
void seed_noise()
{
/* read entropy into initialization variables */
jent_read_entropy(jent, (char*)&pcg_init, sizeof(pcg_init));
{
/* XOR in jitter entropy */
uint64_t buf[2] { 0 };
jent_read_entropy(jent, (char*)&buf, sizeof(buf));
pcg_init[0] ^= buf[0];
pcg_init[1] ^= buf[1];
}
if (Genode::Rdrand::supported()) {
/* XOR in RDRAND */
pcg_init[0] ^= Genode::Rdrand::random64();
pcg_init[1] ^= Genode::Rdrand::random64();
}
/* low bit must be set */
pcg_init[1] |= 1;
pcg32_srandom_r(&pcg, pcg_init[0], pcg_init[1]);