int main() {
write_montgomery(message, r2modm, modulus);
montgomery();
read_r();
for (i = 0; i < SIZE; i++) {
mont_message[i] = r[i];
}
for (i = 0; i < SIZE; i++) {
a[i] = rmodm[i];
}
for (i = 0; i < 2; i++) {
for (j = 0; j < 8; j++) {
write_montgomery(a, a, modulus);
montgomery();
read_r();
for (i = 0; i < SIZE; i++) {
a[i] = r[i];
}
if (get_bit_value(enc_exp[i], 7-j) == 1) {
write_montgomery(a, mont_message, modulus);
montgomery();
read_r();
for (i = 0; i < SIZE; i++) {
a[i] = r[i];
}
}
}
}
write_montgomery(a, one, modulus);
montgomery();
read_r();
for (i = 0; i < SIZE; i++) {
a[i] = r[i];
}
terminate();
return 0;
}
/*
* mg_scale - calculates x * P with montgomery formula.
*
* assumes:
* out != P
* P->z must be 1
*/
static void
mg_scale(struct mg *out, const struct mg *P, const uint8_t x[X25519_KEY_LEN])
{
struct mg T;
int8_t foo;
int i, j;
fld_set0(out->x, 1);
fld_set0(out->z, 0);
memcpy(&T, P, sizeof(struct mg));
for (i = X25519_KEY_LEN-1; i >= 0; i--) {
foo = x[i];
for (j = 8; j > 0; j--, foo <<= 1) {
ctmemswap(out, &T, sizeof(struct mg), foo >> 7);
montgomery(out, &T, P);
ctmemswap(out, &T, sizeof(struct mg), foo >> 7);
}
}
}