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#include "tommath_private.h"
#ifdef BN_MP_RAND_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* Dropbear sets this separately, avoid platform code */
mp_err(*s_mp_rand_source)(void *out, size_t size) = NULL;
void mp_rand_source(mp_err(*source)(void *out, size_t size))
{
/* Dropbear, don't reset to platform if source==NULL */
s_mp_rand_source = source;
}
mp_err mp_rand(mp_int *a, int digits)
{
int i;
mp_err err;
mp_zero(a);
if (digits <= 0) {
return MP_OKAY;
}
if ((err = mp_grow(a, digits)) != MP_OKAY) {
return err;
}
if ((err = s_mp_rand_source(a->dp, (size_t)digits * sizeof(mp_digit))) != MP_OKAY) {
return err;
}
/* TODO: We ensure that the highest digit is nonzero. Should this be removed? */
while ((a->dp[digits - 1] & MP_MASK) == 0u) {
if ((err = s_mp_rand_source(a->dp + digits - 1, sizeof(mp_digit))) != MP_OKAY) {
return err;
}
}
a->used = digits;
for (i = 0; i < digits; ++i) {
a->dp[i] &= MP_MASK;
}
return MP_OKAY;
}
#endif
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