arno/trezor-firmware
1
0
Fork 0
mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-25 15:58:08 +00:00
Code Issues Releases Wiki Activity

rand: switch to 'Numerical Recipes' constants and remove random8 to increase period

Browse Source
This commit is contained in:
Tomas Susanka 2018-12-18 11:56:25 +01:00
parent c5227fdb96
commit 54727e6650
1 changed files with 5 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
rand.c
View File

@ -35,22 +35,13 @@
// You are supposed to replace the random8() and random32() function with your own secure code. // You are supposed to replace the random8() and random32() function with your own secure code.
// There is also a possibility to replace the random_buffer() function as it is defined as a weak symbol. // There is also a possibility to replace the random_buffer() function as it is defined as a weak symbol.
static uint8_t random8(void) uint32_t random32(void)
{ {
// Linear congruential generator used in glibc // Linear congruential generator used in glibc
// https://en.wikipedia.org/wiki/Linear_congruential_generator // https://en.wikipedia.org/wiki/Linear_congruential_generator
static int seed = 0; static uint32_t seed = 0;
seed = (1103515245 * seed + 12345) & 0x7FFFFFFF; seed = 1664525 * seed + 1013904223;
return seed & 0xFF; return seed;
}
uint32_t random32(void)
{
uint32_t r1 = random8();
uint32_t r2 = random8();
uint32_t r3 = random8();
uint32_t r4 = random8();
return ((r1 << 24) | (r2 << 16) | (r3 << 8) | r4);
} }
#endif /* RAND_PLATFORM_INDEPENDENT */ #endif /* RAND_PLATFORM_INDEPENDENT */