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Simplify ep_mul_lwreg.
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@dfaranha
dfaranha committed Mar 30, 2024
1 parent 308412e commit eb8d511
Showing 1 changed file with 48 additions and 59 deletions.
107 changes: 48 additions & 59 deletions src/ep/relic_ep_mul.c
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Original file line number Diff line number Diff line change
Expand Up @@ -212,36 +212,31 @@ static void ep_mul_naf_imp(ep_t r, const ep_t p, const bn_t k) {
#if defined(EP_ENDOM)

static void ep_mul_reg_glv(ep_t r, const ep_t p, const bn_t k) {
int i, j, n0, n1, s0, s1, b0, b1;
int8_t _s0, _s1, reg0[RLC_FP_BITS + 1], reg1[RLC_FP_BITS + 1];
bn_t n, _k, k0, k1, v1[3], v2[3];
ep_t q, t[1 << (RLC_WIDTH - 2)], u, v, w;
int8_t reg[2][RLC_FP_BITS + 1], s[2], b[2], c0, c1, n0, n1;
bn_t n, _k[2], v1[3], v2[3];
ep_t q, t[1 << (RLC_WIDTH - 2)], u, w;
size_t l;

bn_null(n);
bn_null(_k);
bn_null(k0);
bn_null(k1);
bn_null(_k[0]);
bn_null(_k[1]);
ep_null(q);
ep_null(u);
ep_null(v);
ep_null(w);

RLC_TRY {
bn_new(n);
bn_new(_k);
bn_new(k0);
bn_new(k1);
bn_new(_k[0]);
bn_new(_k[1]);
ep_new(q);
ep_new(u);
ep_new(v);
ep_new(w);

for (i = 0; i < (1 << (RLC_WIDTH - 2)); i++) {
for (size_t i = 0; i < (1 << (RLC_WIDTH - 2)); i++) {
ep_null(t[i]);
ep_new(t[i]);
}
for (i = 0; i < 3; i++) {
for (size_t i = 0; i < 3; i++) {
bn_null(v1[i]);
bn_null(v2[i]);
bn_new(v1[i]);
Expand All @@ -252,27 +247,25 @@ static void ep_mul_reg_glv(ep_t r, const ep_t p, const bn_t k) {
ep_curve_get_v1(v1);
ep_curve_get_v2(v2);

bn_mod(_k, k, n);
bn_mod(_k[0], k, n);

bn_rec_glv(k0, k1, _k, n, (const bn_t *)v1, (const bn_t *)v2);
s0 = bn_sign(k0);
s1 = bn_sign(k1);
bn_abs(k0, k0);
bn_abs(k1, k1);
b0 = bn_is_even(k0);
b1 = bn_is_even(k1);
k0->dp[0] |= b0;
k1->dp[0] |= b1;

ep_copy(q, p);
ep_neg(t[0], p);
dv_copy_cond(q->y, t[0]->y, RLC_FP_DIGS, s0 != RLC_POS);
bn_rec_glv(_k[0], _k[1], _k[0], n, (const bn_t *)v1, (const bn_t *)v2);
for (size_t i = 0; i < 2; i++) {
s[i] = bn_sign(_k[i]);
bn_abs(_k[i], _k[i]);
b[i] = bn_is_even(_k[i]);
_k[i]->dp[0] |= b[i];
}

ep_norm(t[0], p);
ep_neg(q, t[0]);
dv_copy_cond(q->y, t[0]->y, RLC_FP_DIGS, s[0] == RLC_POS);
ep_tab(t, q, RLC_WIDTH);

l = RLC_FP_BITS + 1;
bn_rec_reg(reg0, &l, k0, bn_bits(n) >> 1, RLC_WIDTH);
bn_rec_reg(reg[0], &l, _k[0], bn_bits(n) >> 1, RLC_WIDTH);
l = RLC_FP_BITS + 1;
bn_rec_reg(reg1, &l, k1, bn_bits(n) >> 1, RLC_WIDTH);
bn_rec_reg(reg[1], &l, _k[1], bn_bits(n) >> 1, RLC_WIDTH);

#if defined(EP_MIXED)
fp_set_dig(u->z, 1);
Expand All @@ -282,19 +275,19 @@ static void ep_mul_reg_glv(ep_t r, const ep_t p, const bn_t k) {
u->coord = w->coord = EP_ADD;
#endif
ep_set_infty(r);
for (i = l - 1; i >= 0; i--) {
for (j = 0; j < RLC_WIDTH - 1; j++) {
for (int i = l - 1; i >= 0; i--) {
for (size_t j = 0; j < RLC_WIDTH - 1; j++) {
ep_dbl(r, r);
}

n0 = reg0[i];
_s0 = (n0 >> 7);
n0 = ((n0 ^ _s0) - _s0) >> 1;
n1 = reg1[i];
_s1 = (n1 >> 7);
n1 = ((n1 ^ _s1) - _s1) >> 1;
n0 = reg[0][i];
c0 = (n0 >> 7);
n0 = ((n0 ^ c0) - c0) >> 1;
n1 = reg[1][i];
c1 = (n1 >> 7);
n1 = ((n1 ^ c1) - c1) >> 1;

for (j = 0; j < (1 << (RLC_WIDTH - 2)); j++) {
for (size_t j = 0; j < (1 << (RLC_WIDTH - 2)); j++) {
dv_copy_cond(u->x, t[j]->x, RLC_FP_DIGS, j == n0);
dv_copy_cond(w->x, t[j]->x, RLC_FP_DIGS, j == n1);
dv_copy_cond(u->y, t[j]->y, RLC_FP_DIGS, j == n0);
Expand All @@ -304,31 +297,29 @@ static void ep_mul_reg_glv(ep_t r, const ep_t p, const bn_t k) {
dv_copy_cond(w->z, t[j]->z, RLC_FP_DIGS, j == n1);
#endif
}
ep_neg(v, u);
dv_copy_cond(u->y, v->y, RLC_FP_DIGS, _s0 != 0);
ep_add(r, r, u);
ep_neg(q, u);
dv_copy_cond(q->y, u->y, RLC_FP_DIGS, c0 == 0);
ep_add(r, r, q);

ep_psi(w, w);
ep_neg(q, w);
dv_copy_cond(w->y, q->y, RLC_FP_DIGS, s0 != s1);
ep_neg(q, w);
dv_copy_cond(w->y, q->y, RLC_FP_DIGS, _s1 != 0);
dv_copy_cond(w->y, q->y, RLC_FP_DIGS, (c1 != 0) ^ (s[0] != s[1]));
ep_add(r, r, w);
}

/* t[0] has an unmodified copy of p. */
ep_sub(u, r, t[0]);
dv_copy_cond(r->x, u->x, RLC_FP_DIGS, b0);
dv_copy_cond(r->y, u->y, RLC_FP_DIGS, b0);
dv_copy_cond(r->z, u->z, RLC_FP_DIGS, b0);
dv_copy_cond(r->x, u->x, RLC_FP_DIGS, b[0]);
dv_copy_cond(r->y, u->y, RLC_FP_DIGS, b[0]);
dv_copy_cond(r->z, u->z, RLC_FP_DIGS, b[0]);

ep_psi(w, t[0]);
ep_neg(q, w);
dv_copy_cond(w->y, q->y, RLC_FP_DIGS, s0 != s1);
ep_sub(u, r, w);
dv_copy_cond(r->x, u->x, RLC_FP_DIGS, b1);
dv_copy_cond(r->y, u->y, RLC_FP_DIGS, b1);
dv_copy_cond(r->z, u->z, RLC_FP_DIGS, b1);
dv_copy_cond(q->y, w->y, RLC_FP_DIGS, s[0] == s[1]);
ep_sub(u, r, q);
dv_copy_cond(r->x, u->x, RLC_FP_DIGS, b[1]);
dv_copy_cond(r->y, u->y, RLC_FP_DIGS, b[1]);
dv_copy_cond(r->z, u->z, RLC_FP_DIGS, b[1]);

/* Convert r to affine coordinates. */
ep_norm(r, r);
Expand All @@ -338,18 +329,16 @@ static void ep_mul_reg_glv(ep_t r, const ep_t p, const bn_t k) {
}
RLC_FINALLY {
bn_free(n);
bn_free(_k);
bn_free(k0);
bn_free(k1);
bn_free(_k[0]);
bn_free(_k[1]);
bn_free(n);
ep_free(q);
ep_free(u);
ep_free(v);
ep_free(w);
for (i = 0; i < 1 << (RLC_WIDTH - 2); i++) {
for (size_t i = 0; i < 1 << (RLC_WIDTH - 2); i++) {
ep_free(t[i]);
}
for (i = 0; i < 3; i++) {
for (size_t i = 0; i < 3; i++) {
bn_free(v1[i]);
bn_free(v2[i]);
}
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