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CHG: the mifare Auth command can make use of a random nonce aswell.

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CHG: since sim commands are timing critical, I'm testing a smaller prand prng function from Intel
This commit is contained in:
iceman1001 2017-01-29 10:41:48 +01:00
commit e99acd00cc
5 changed files with 81 additions and 64 deletions
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25
common/random.c
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@ -1,6 +1,6 @@
#include "random.h"
uint64_t next_random = 1;
static uint32_t g_nextrandom;
/* Generates a (non-cryptographically secure) 32-bit random number.
*
@ -8,14 +8,23 @@
* method of seeding with the time it took to call "autoseed" from first run.
*
* https://github.com/Proxmark/proxmark3/pull/209/commits/f9c1dcd9f6e68a8c07cffed697a9c4c8caed6015
*
* Iceman, rand needs to be fast.
* https://software.intel.com/en-us/articles/fast-random-number-generator-on-the-intel-pentiumr-4-processor/
*/
inline void fast_prand(){
fast_prandEx(GetTickCount());
}
inline void fast_prandEx(uint32_t seed) {
g_nextrandom = seed;
}
uint32_t prand() {
if (next_random == 1)
next_random = GetTickCount();
next_random *= 6364136223846793005;
next_random += 1;
return (uint32_t)(next_random >> 32) % 0xffffffff;
// g_nextrandom *= 6364136223846793005;
// g_nextrandom += 1;
//return (uint32_t)(g_nextrandom >> 32) % 0xffffffff;
g_nextrandom = (214013 * g_nextrandom + 2531011);
return (g_nextrandom>>16) & 0xFFFF;
}

4
common/random.h
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@ -15,7 +15,7 @@
#include "common.h"
#include "ticks.h"
void fast_prand();
void fast_prandEx(uint32_t seed);
uint32_t prand();
#endif