JehanneOS/mksh
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use a slightly different algorithm for arc4random_pushb interfacing:

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rate-limit calls to CryptGenRandom to every 2‥4 minutes, if the last
call was successful, and operate with hash() on rnd_cache[], so that
it is mixed in a better way
This commit is contained in:
tg 2009-09-20 13:29:18 +00:00
parent 3630e1f7dc
commit ca8b2b534c
1 changed files with 47 additions and 10 deletions
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57
var.c
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@ -22,7 +22,7 @@
#include "sh.h"
__RCSID("$MirOS: src/bin/mksh/var.c,v 1.88 2009/09/20 13:08:12 tg Exp $");
__RCSID("$MirOS: src/bin/mksh/var.c,v 1.89 2009/09/20 13:29:18 tg Exp $");
/*
* Variables
@ -973,6 +973,47 @@ makenv(void)
#if HAVE_ARC4RANDOM && !defined(MKSH_SMALL)
static uint32_t rnd_cache[2];
static unsigned char rnd_lastflag = 2;
static void rnd_cachemix(unsigned long);
static void
rnd_cachemix(unsigned long newval)
{
size_t i;
struct {
union {
int rval;
uint32_t arval;
} v0;
uint32_t v1;
uint32_t v2;
unsigned long v3;
} v;
unsigned char buf[sizeof(v) * 2 + 1], *cp, num;
v.v0.rval = rand();
v.v1 = rnd_cache[0];
v.v2 = rnd_cache[1];
v.v3 = newval;
num = 0;
loop:
cp = (void *)&v;
i = 0;
while (i < 2 * sizeof(v)) {
buf[i++] = digits_uc[*cp >> 4];
buf[i++] = digits_lc[*cp & 0x0F];
++cp;
}
buf[i] = 0;
rnd_cache[num] = hash(buf);
if (num == 0) {
++num;
v.v0.arval = arc4random();
goto loop;
}
}
#endif
static int
@ -986,14 +1027,12 @@ rnd_get(void)
uint32_t rv = 0;
#endif
if (Flag(FARC4RANDOM) != rnd_lastflag) {
if (Flag(FARC4RANDOM) == 0) {
if (Flag(FARC4RANDOM) == 0)
/* transition to 0 by set: srand */
srand(arc4random() & 0x7FFF);
} else if (rnd_lastflag == 0) {
else if (rnd_lastflag == 0)
/* transition from 0: addrandom */
rnd_cache[0] ^= rand();
rnd_cache[1] ^= rand();
}
rnd_cachemix(rand());
rnd_lastflag = Flag(FARC4RANDOM);
}
if (Flag(FARC4RANDOM)) {
@ -1027,8 +1066,7 @@ rnd_set(unsigned long newval)
#endif
#else
#if HAVE_ARC4RANDOM
rnd_cache[0] ^= (newval << 15) | rand();
rnd_cache[1] ^= newval >> 17;
rnd_cachemix(newval);
if (Flag(FARC4RANDOM) == 1)
return;
if (Flag(FARC4RANDOM) == 2)
@ -1053,8 +1091,7 @@ change_random(unsigned long newval)
#if HAVE_ARC4RANDOM
if (Flag(FARC4RANDOM)) {
rnd_cache[0] ^= (newval << 15) | rand();
rnd_cache[1] ^= newval >> 17;
rnd_cachemix(newval);
return;
}
#endif