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SP int: Montgomery Reduction

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Improve performance for ECC curves when all bits in words are used (mask
is 0).
On 64-bit platforms, improves performance for 256 and 384 bit curves.
On 32-bit platforms, improves performance for 224, 256, 384 bit curves.
This commit is contained in:
Sean Parkinson
2022-02-15 17:19:57 +10:00
parent 9906c9c55e
commit ea5785f6fd
1 changed files with 101 additions and 35 deletions
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136
wolfcrypt/src/sp_int.c
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@ -14201,7 +14201,7 @@ static int _sp_mont_red(sp_int* a, sp_int* m, sp_int_digit mp)
}
#ifndef WOLFSSL_HAVE_SP_ECC
#if SP_WORD_SIZE == 64
else if (m->used == 4) {
else if ((m->used == 4) && (mask == 0)) {
sp_int_digit l;
sp_int_digit h;
sp_int_digit o2;
@ -14211,41 +14211,45 @@ static int _sp_mont_red(sp_int* a, sp_int* m, sp_int_digit mp)
o = 0;
o2 = 0;
for (i = 0; i < 4; i++) {
mu = mp * a->dp[i];
if ((i == 3) && (mask != 0)) {
mu &= mask;
}
l = a->dp[i];
mu = mp * a->dp[0];
l = a->dp[0];
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[0]);
a->dp[i] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 1]);
SP_ASM_ADDC(l, h, a->dp[1]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[1]);
a->dp[i + 1] = l;
a->dp[0] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 2]);
SP_ASM_ADDC(l, h, a->dp[2]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[2]);
a->dp[i + 2] = l;
a->dp[1] = l;
l = h;
h = o2;
o2 = 0;
SP_ASM_ADDC_REG(l, h, o);
SP_ASM_ADDC(l, h, a->dp[i + 3]);
SP_ASM_MUL_ADD(l, h, o2, mu, m->dp[3]);
a->dp[i + 3] = l;
a->dp[2] = l;
o = h;
l = h;
h = 0;
}
h = o2;
SP_ASM_ADDC(l, h, a->dp[7]);
a->dp[7] = l;
a->dp[8] = h;
a->used = 9;
a->dp[3] = l;
a->dp[4] = h;
a->used = 5;
sp_clamp(a);
if (_sp_cmp_abs(a, m) != MP_LT) {
sp_sub(a, m, a);
}
return MP_OKAY;
}
else if (m->used == 6) {
else if ((m->used == 6) && (mask == 0)) {
sp_int_digit l;
sp_int_digit h;
sp_int_digit o2;
@ -14255,51 +14259,113 @@ static int _sp_mont_red(sp_int* a, sp_int* m, sp_int_digit mp)
o = 0;
o2 = 0;
for (i = 0; i < 6; i++) {
mu = mp * a->dp[i];
if ((i == 5) && (mask != 0)) {
mu &= mask;
}
l = a->dp[i];
mu = mp * a->dp[0];
l = a->dp[0];
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[0]);
a->dp[i] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 1]);
SP_ASM_ADDC(l, h, a->dp[1]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[1]);
a->dp[i + 1] = l;
a->dp[0] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 2]);
SP_ASM_ADDC(l, h, a->dp[2]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[2]);
a->dp[i + 2] = l;
a->dp[1] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 3]);
SP_ASM_ADDC(l, h, a->dp[3]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[3]);
a->dp[i + 3] = l;
a->dp[2] = l;
l = h;
h = 0;
SP_ASM_ADDC(l, h, a->dp[i + 4]);
SP_ASM_ADDC(l, h, a->dp[4]);
SP_ASM_MUL_ADD_NO(l, h, mu, m->dp[4]);
a->dp[i + 4] = l;
a->dp[3] = l;
l = h;
h = o2;
o2 = 0;
SP_ASM_ADDC_REG(l, h, o);
SP_ASM_ADDC(l, h, a->dp[i + 5]);
SP_ASM_MUL_ADD(l, h, o2, mu, m->dp[5]);
a->dp[i + 5] = l;
a->dp[4] = l;
o = h;
l = h;
h = 0;
}
h = o2;
SP_ASM_ADDC(l, h, a->dp[11]);
a->dp[11] = l;
a->dp[12] = h;
a->used = 13;
a->dp[5] = l;
a->dp[6] = h;
a->used = 7;
sp_clamp(a);
if (_sp_cmp_abs(a, m) != MP_LT) {
sp_sub(a, m, a);
}
return MP_OKAY;
}
#endif /* SP_WORD_SIZE == 64 */
#elif SP_WORD_SIZE == 32
else if ((m->used <= 12) && (mask == 0)) {
sp_int_digit l;
sp_int_digit h;
sp_int_digit o2;
sp_int_digit* ad;
sp_int_digit* md;
o = 0;
o2 = 0;
ad = a->dp;
for (i = 0; i < m->used; i++) {
md = m->dp;
mu = mp * ad[0];
l = ad[0];
h = 0;
SP_ASM_MUL_ADD_NO(l, h, mu, *(md++));
l = h;
for (j = 1; j + 1 < m->used - 1; j += 2) {
h = 0;
SP_ASM_ADDC(l, h, ad[j]);
SP_ASM_MUL_ADD_NO(l, h, mu, *(md++));
ad[j - 1] = l;
l = 0;
SP_ASM_ADDC(h, l, ad[j + 1]);
SP_ASM_MUL_ADD_NO(h, l, mu, *(md++));
ad[j] = h;
}
for (; j < m->used - 1; j++) {
h = 0;
SP_ASM_ADDC(l, h, ad[j]);
SP_ASM_MUL_ADD_NO(l, h, mu, *(md++));
ad[j - 1] = l;
l = h;
}
h = o2;
o2 = 0;
SP_ASM_ADDC_REG(l, h, o);
SP_ASM_ADDC(l, h, ad[i + j]);
SP_ASM_MUL_ADD(l, h, o2, mu, *md);
ad[j - 1] = l;
o = h;
}
l = o;
h = o2;
SP_ASM_ADDC(l, h, a->dp[m->used * 2 - 1]);
a->dp[m->used - 1] = l;
a->dp[m->used] = h;
a->used = m->used + 1;
sp_clamp(a);
if (_sp_cmp_abs(a, m) != MP_LT) {
sp_sub(a, m, a);
}
return MP_OKAY;
}
#endif /* SP_WORD_SIZE == 64 | 32 */
#endif /* WOLFSSL_HAVE_SP_ECC */
else {
sp_int_digit l;