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Make LWREG use table.
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@dfaranha
dfaranha committed Mar 30, 2024
1 parent eb8d511 commit 69d7dc6
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Showing 2 changed files with 74 additions and 38 deletions.
4 changes: 3 additions & 1 deletion include/relic_epx.h
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Original file line number Diff line number Diff line change
Expand Up @@ -477,7 +477,9 @@ typedef iso2_st *iso2_t;
#define ep2_mul(R, P, K) ep2_mul_slide(R, P, K)
#elif EP_MUL == MONTY
#define ep2_mul(R, P, K) ep2_mul_monty(R, P, K)
#elif EP_MUL == LWNAF || EP_MUL == LWREG
#elif EP_MUL == LWNAF
#define ep2_mul(R, P, K) ep2_mul_lwnaf(R, P, K)
#elif EP_MUL == LWREG
#define ep2_mul(R, P, K) ep2_mul_lwnaf(R, P, K)
#endif

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108 changes: 71 additions & 37 deletions src/epx/relic_ep2_mul.c
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Original file line number Diff line number Diff line change
Expand Up @@ -169,76 +169,107 @@ static void ep2_mul_naf_imp(ep2_t r, const ep2_t p, const bn_t k) {
#if defined(EP_ENDOM)

static void ep2_mul_reg_gls(ep2_t r, const ep2_t p, const bn_t k) {
size_t l, _l[4];
int8_t reg[4][RLC_FP_BITS + 1], b[4], s[4], c0, n0;
bn_t n, _k[4], u;
int8_t reg[4][RLC_FP_BITS + 1], b[4], s[4], c0, c1;
ep2_t q[4], t;
ep2_t q, w, t[4][1 << (RLC_WIDTH - 2)];
size_t l, len, _l[4];

bn_null(n);
bn_null(u);
ep2_null(t);
ep2_null(q);
ep2_null(w);

RLC_TRY {
bn_new(n);
bn_new(u);
for (int i = 0; i < 4; i++) {
ep2_new(q);
ep2_new(w);
for (size_t i = 0; i < 4; i++) {
bn_null(_k[i]);
ep2_null(q[i]);
bn_new(_k[i]);
ep2_new(q[i]);
for (size_t j = 0; j < (1 << (RLC_WIDTH - 2)); j++) {
ep2_null(t[i][j]);
ep2_new(t[i][j]);
}
}
ep2_new(t);

ep2_curve_get_ord(n);
fp_prime_get_par(u);
bn_mod(_k[0], k, n);
bn_rec_frb(_k, 4, _k[0], u, n, ep_curve_is_pairf() == EP_BN);

ep2_norm(q[0], p);
ep2_frb(q[1], q[0], 1);
ep2_frb(q[2], q[1], 1);
ep2_frb(q[3], q[2], 1);

l = 0;
for (int i = 0; i < 4; i++) {
len = bn_bits(u) + (ep_curve_is_pairf() == EP_BN);
ep2_norm(t[0][0], p);
for (size_t i = 0; i < 4; 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];

/* Make some extra room for BN curves that grow subscalars by 1. */
l = bn_bits(u) + (ep_curve_is_pairf() == EP_BN);
_l[i] = RLC_FP_BITS + 1;
bn_rec_reg(reg[i], &_l[i], _k[i], l, 2);
bn_rec_reg(reg[i], &_l[i], _k[i], len, RLC_WIDTH);
l = RLC_MAX(l, _l[i]);

/* Apply Frobenius before flipping sign to build table. */
if (i > 0) {
ep2_frb(t[i][0], t[i - 1][0], 1);
}
}

for (size_t i = 0; i < 4; i++) {
ep2_neg(q, t[i][0]);
dv_copy_cond(q->y[0], t[i][0]->y[0], RLC_FP_DIGS, s[i] == RLC_POS);
dv_copy_cond(q->y[1], t[i][0]->y[1], RLC_FP_DIGS, s[i] == RLC_POS);
ep2_tab(t[i], q, RLC_WIDTH);
}

#if defined(EP_MIXED)
fp2_set_dig(w->z, 1);
w->coord = BASIC;
#else
w->coord = = EP_ADD;
#endif

ep2_set_infty(r);
for (int j = l - 1; j >= 0; j--) {
ep2_dbl(r, r);
for (size_t i = 0; i < RLC_WIDTH - 1; i++) {
ep2_dbl(r, r);
}

for (int i = 0; i < 4; i++) {
c0 = reg[i][j] > 0;
c1 = s[i] == RLC_POS;
for (size_t i = 0; i < 4; i++) {
n0 = reg[i][j];
c0 = (n0 >> 7);
n0 = ((n0 ^ c0) - c0) >> 1;

for (size_t m = 0; m < (1 << (RLC_WIDTH - 2)); m++) {
dv_copy_cond(w->x[0], t[i][m]->x[0], RLC_FP_DIGS, m == n0);
dv_copy_cond(w->x[1], t[i][m]->x[1], RLC_FP_DIGS, m == n0);
dv_copy_cond(w->y[0], t[i][m]->y[0], RLC_FP_DIGS, m == n0);
dv_copy_cond(w->y[1], t[i][m]->y[1], RLC_FP_DIGS, m == n0);
#if !defined(EP_MIXED)
dv_copy_cond(w->z[0], t[i][m]->z[0], RLC_FP_DIGS, m == n0);
dv_copy_cond(w->z[1], t[i][m]->z[1], RLC_FP_DIGS, m == n0);
#endif
}

ep2_neg(t, q[i]);
dv_copy_cond(t->y[0], q[i]->y[0], RLC_FP_DIGS, c0 == c1);
dv_copy_cond(t->y[1], q[i]->y[1], RLC_FP_DIGS, c0 == c1);
ep2_add(r, r, t);
ep2_neg(q, w);
dv_copy_cond(q->y[0], w->y[0], RLC_FP_DIGS, c0 == 0);
dv_copy_cond(q->y[1], w->y[1], RLC_FP_DIGS, c0 == 0);
ep2_add(r, r, q);
}
}

for (int i = 0; i < 4; i++) {
ep2_neg(t, q[i]);
dv_copy_cond(t->y[0], q[i]->y[0], RLC_FP_DIGS, s[i] == RLC_NEG);
dv_copy_cond(t->y[1], q[i]->y[1], RLC_FP_DIGS, s[i] == RLC_NEG);
ep2_add(t, r, t);
dv_copy_cond(r->x[0], t->x[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->x[1], t->x[1], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->y[0], t->y[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->y[1], t->y[1], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->z[0], t->z[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->z[1], t->z[1], RLC_FP_DIGS, b[i]);
for (size_t i = 0; i < 4; i++) {
/* Tables are built with points already negated, so no need here. */
ep2_sub(q, r, t[i][0]);
dv_copy_cond(r->x[0], q->x[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->x[1], q->x[1], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->y[0], q->y[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->y[1], q->y[1], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->z[0], q->z[0], RLC_FP_DIGS, b[i]);
dv_copy_cond(r->z[1], q->z[1], RLC_FP_DIGS, b[i]);
}

/* Convert r to affine coordinates. */
Expand All @@ -250,11 +281,14 @@ static void ep2_mul_reg_gls(ep2_t r, const ep2_t p, const bn_t k) {
RLC_FINALLY {
bn_free(n);
bn_free(u);
ep2_free(q);
ep2_free(w);
for (int i = 0; i < 4; i++) {
bn_free(_k[i]);
ep2_free(q[i]);
for (size_t j = 0; j < (1 << (RLC_WIDTH - 2)); j++) {
ep2_free(t[i][j]);
}
}
ep2_free(t);
}
}

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