static void point_add(struct point *r, struct point *p, struct point *q)
{
u8 s[20], t[20], u[20];
u8 *px, *py, *qx, *qy, *rx, *ry;
struct point pp, qq;
pp = *p;
qq = *q;
px = pp.x;
py = pp.y;
qx = qq.x;
qy = qq.y;
rx = r->x;
ry = r->y;
if (point_is_zero(&pp)) {
elt_copy(rx, qx);
elt_copy(ry, qy);
return;
}
if (point_is_zero(&qq)) {
elt_copy(rx, px);
elt_copy(ry, py);
return;
}
elt_sub(u, qx, px);
if (elt_is_zero(u)) {
elt_sub(u, qy, py);
if (elt_is_zero(u))
point_double(r, &pp);
else
point_zero(r);
return;
}
elt_inv(t, u); // t = 1/(qx-px)
elt_sub(u, qy, py); // u = qy-py
elt_mul(s, t, u); // s = (qy-py)/(qx-px)
elt_square(rx, s); // rx = s*s
elt_add(t, px, qx); // t = px+qx
elt_sub(rx, rx, t); // rx = s*s - (px+qx)
elt_sub(t, px, rx); // t = -(rx-px)
elt_mul(ry, s, t); // ry = -s*(rx-px)
elt_sub(ry, ry, py); // ry = -s*(rx-px) - py
}
struct elt * instr_get_result(const struct instr * i)
{
struct elt *e;
switch (i->optype) {
case I_RAW:
e = NULL;
break;
case I_CAST:
e = elt_copy(i->res);
break;
case I_CAL:
e = elt_copy(i->ret);
break;
default:
e = elt_copy(i->er);
}
return e;
}
void * instr_copy(void * instruction)
{
struct instr *copy;
struct instr * i = (struct instr *)instruction;
if (i->optype == I_RAW) {
copy = malloc(sizeof *copy);
copy->rawllvm = strdup(i->rawllvm);
}
else if (i->optype == I_CAST) {
copy = malloc(sizeof *copy);
copy->cast_func = i->cast_func;
copy->tocast = elt_copy(i->tocast);
copy->res = elt_copy(i->res);
}
else if (i->optype == I_CAL) {
copy = malloc(sizeof *copy);
copy->fn = strdup(i->fn);
copy->args = stack_copy(i->args, elt_copy);
copy->ret = elt_copy(i->ret);
}
else {
copy = instr_new(i->optype,
i->vr,
elt_copy(i->er),
elt_copy(i->e1),
elt_copy(i->e2)
);
}
return copy;
}
static void generate_ecdsa(u8 *R, u8 *S, u8 *k, u8 *hash)
{
u8 e[21];
u8 kk[21];
u8 m[21];
u8 minv[21];
struct point mG;
FILE *fp;
e[0] = 0;
memcpy(e + 1, hash, 20);
bn_reduce(e, ec_N, 21);
try_again:
fp = fopen("/dev/random", "rb");
if (fread(m, sizeof m, 1, fp) != 1)
fail("reading random");
fclose(fp);
m[0] = 0;
if (bn_compare(m, ec_N, 21) >= 0)
goto try_again;
// R = (mG).x
point_mul(&mG, m, &ec_G);
point_from_mon(&mG);
R[0] = 0;
elt_copy(R+1, mG.x);
// S = m**-1*(e + Rk) (mod N)
bn_copy(kk, k, 21);
bn_reduce(kk, ec_N, 21);
bn_to_mon(m, ec_N, 21);
bn_to_mon(e, ec_N, 21);
bn_to_mon(R, ec_N, 21);
bn_to_mon(kk, ec_N, 21);
bn_mon_mul(S, R, kk, ec_N, 21);
bn_add(kk, S, e, ec_N, 21);
bn_mon_inv(minv, m, ec_N, 21);
bn_mon_mul(S, minv, kk, ec_N, 21);
bn_from_mon(R, ec_N, 21);
bn_from_mon(S, ec_N, 21);
}
static void generate_ecdsa(u8 *R, u8 *S, u8 *k, u8 *hash)
{
u8 e[21];
u8 kk[21];
u8 m[21];
u8 minv[21];
struct point mG;
e[0] = 0;
memcpy(e + 1, hash, 20);
bn_reduce(e, ec_N, 21);
try_again:
get_rand(m, sizeof m);
m[0] = 0;
if (bn_compare(m, ec_N, 21) >= 0)
goto try_again;
// R = (mG).x
point_mul(&mG, m, &ec_G);
point_from_mon(&mG);
R[0] = 0;
elt_copy(R+1, mG.x);
// S = m**-1*(e + Rk) (mod N)
bn_copy(kk, k, 21);
bn_reduce(kk, ec_N, 21);
bn_to_mon(m, ec_N, 21);
bn_to_mon(e, ec_N, 21);
bn_to_mon(R, ec_N, 21);
bn_to_mon(kk, ec_N, 21);
bn_mon_mul(S, R, kk, ec_N, 21);
bn_add(kk, S, e, ec_N, 21);
bn_mon_inv(minv, m, ec_N, 21);
bn_mon_mul(S, minv, kk, ec_N, 21);
bn_from_mon(R, ec_N, 21);
bn_from_mon(S, ec_N, 21);
}
static void elt_inv(u8 *d, u8 *a)
{
u8 s[20];
elt_copy(s, a);
bn_mon_inv(d, s, ec_p, 20);
}
