/*
* TEE_BigIntMulMod
*/
void TEE_BigIntMulMod(TEE_BigInt *dest, const TEE_BigInt *op1,
const TEE_BigInt *op2, const TEE_BigInt *n)
{
mpanum mpa_dest = (mpa_num_base *)dest;
mpanum mpa_op1 = (mpa_num_base *)op1;
mpanum mpa_op2 = (mpa_num_base *)op2;
mpanum mpa_n = (mpa_num_base *)n;
mpanum tmp_dest;
if (TEE_BigIntCmpS32(n, 2) < 0)
TEE_BigInt_Panic("Modulus is too short");
/*
* From the spec, mpa_dest must be of magnitude "mpa_n"
* But internal computations in mpa do not have such assumptions
* (as __mpa_div_q_r, where "r" must be of magnitude "op1",
* whereas GP provides a magnitude of "op2")
* This is a tempory variable is used, before storing the
* final result.
*/
mpa_alloc_static_temp_var(&tmp_dest, mempool);
mpa_mul_mod(tmp_dest, mpa_op1, mpa_op2, mpa_n, mempool);
if (mpa_cmp_short(tmp_dest, 0) < 0)
mpa_add(tmp_dest, tmp_dest, mpa_n, mempool);
mpa_copy(mpa_dest, tmp_dest);
mpa_free_static_temp_var(&tmp_dest, mempool);
}
static int mulmod(void *a, void *b, void *c, void *d)
{
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(b != NULL);
LTC_ARGCHK(c != NULL);
LTC_ARGCHK(d != NULL);
void *tmpa, *tmpb;
mp_init_multi(&tmpa, &tmpb, NULL);
mod(a, c, tmpa);
mod(b, c, tmpb);
mpa_mul_mod((mpanum) d, (const mpanum) tmpa, (const mpanum) tmpb, (const mpanum) c, external_mem_pool);
mp_clear_multi(tmpa, tmpb, NULL);
return CRYPT_OK;
}