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POLY: cleanup pb_starmultiply() 

* avoid side effects
* use MP_DIV instead of MP_MOD
* move mp_modulus initialization to outer scope
This commit is contained in:
hasufell 2014-04-17 17:36:57 +02:00 committed by malte
parent 01785678f0
commit 6990193dcd
2 changed files with 24 additions and 8 deletions
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24
src/poly.c
View File

@ -178,6 +178,17 @@ void pb_starmultiply(pb_poly *a,
ntru_context *ctx,
unsigned int modulus)
{
pb_poly *a_tmp;
mp_int mp_modulus;
init_integer(&mp_modulus);
mp_set_int(&mp_modulus, (unsigned long)(modulus));
/* avoid side effects */
a_tmp = build_polynom(NULL, ctx->N, ctx);
PB_COPY(a, a_tmp);
erase_polynom(c, ctx->N);
for (int k = ctx->N - 1; k >= 0; k--) {
int j;
j = k + 1;
@ -185,26 +196,23 @@ void pb_starmultiply(pb_poly *a,
for (int i = ctx->N - 1; i >= 0; i--) {
if (j == (int)(ctx->N))
j = 0;
if (mp_cmp_d(&(a->terms[i]), 0) != MP_EQ &&
if (mp_cmp_d(&(a_tmp->terms[i]), 0) != MP_EQ &&
mp_cmp_d(&(b->terms[j]), 0) != MP_EQ) {
int result;
mp_int mp_modulus;
mp_int mp_tmp;
init_integer(&mp_tmp);
init_integer(&mp_modulus);
mp_set_int(&mp_modulus, (unsigned long)(modulus));
MP_MUL(&(a->terms[i]), &(b->terms[j]), &mp_tmp);
MP_MUL(&(a_tmp->terms[i]), &(b->terms[j]), &mp_tmp);
MP_ADD(&(c->terms[k]), &mp_tmp, &(c->terms[k]));
MP_MOD(&(c->terms[k]), &mp_modulus, &(c->terms[k]));
MP_DIV(&(c->terms[k]), &mp_modulus, NULL, &(c->terms[k]));
mp_clear(&mp_modulus);
mp_clear(&mp_tmp);
}
j++;
}
}
mp_clear(&mp_modulus);
delete_polynom(a_tmp);
}
/**

8
src/poly.h
View File

@ -38,6 +38,14 @@
mp_error_to_string(result)); \
}
#define MP_DIV(...) \
{ \
int result; \
if ((result = mp_div(__VA_ARGS__)) != MP_OKAY) \
NTRU_ABORT("Error dividing terms. %s", \
mp_error_to_string(result)); \
}
#define MP_ADD(...) \
{ \
int result; \