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tls: another P256 code shrink

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Propagate constant arrays and scalars deeper down call chain.
Use sp_256_mont_mul_10 to implement sp_256_mont_sqr_10.

function                                             old     new   delta
sp_256_mont_mul_10                                     -     214    +214
sp_256_mont_reduce_10                                  -     178    +178
sp_256_mont_sqr_10                                     -       7      +7
static.sp_256_mont_reduce_10                         178       -    -178
static.sp_256_mont_mul_10                            214       -    -214
static.sp_256_mont_sqr_10                            234       -    -234
------------------------------------------------------------------------------
(add/remove: 3/3 grow/shrink: 0/0 up/down: 399/-626)         Total: -227 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-05 13:39:33 +02:00
parent e730505034
commit 389329efbe
1 changed files with 54 additions and 69 deletions
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123
networking/tls_sp_c32.c
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@ -213,34 +213,7 @@ static void sp_256_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b)
r[0] = (sp_digit)(c >> 26); r[0] = (sp_digit)(c >> 26);
} }
/* Square a and put result in r. (r = a * a) */ /* Shift number right one bit. Bottom bit is lost. */
static void sp_256_sqr_10(sp_digit* r, const sp_digit* a)
{
int i, j, k;
int64_t c;
c = ((int64_t)a[9]) * a[9];
r[19] = (sp_digit)(c >> 26);
c = (c & 0x3ffffff) << 26;
for (k = 17; k >= 0; k--) {
for (i = 9; i >= 0; i--) {
j = k - i;
if (j >= 10 || i <= j)
break;
if (j < 0)
continue;
c += ((int64_t)a[i]) * a[j] * 2;
}
if (i == j)
c += ((int64_t)a[i]) * a[i];
r[k + 2] += c >> 52;
r[k + 1] = (c >> 26) & 0x3ffffff;
c = (c & 0x3ffffff) << 26;
}
r[0] = (sp_digit)(c >> 26);
}
/* Shift number left one bit. Bottom bit is lost. */
static void sp_256_rshift1_10(sp_digit* r, sp_digit* a) static void sp_256_rshift1_10(sp_digit* r, sp_digit* a)
{ {
int i; int i;
@ -343,8 +316,11 @@ static void sp_256_mul_add_10(sp_digit* r, const sp_digit* a, sp_digit b)
* m The single precision number representing the modulus. * m The single precision number representing the modulus.
* mp The digit representing the negative inverse of m mod 2^n. * mp The digit representing the negative inverse of m mod 2^n.
*/ */
static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp) static void sp_256_mont_reduce_10(sp_digit* a /*, const sp_digit* m, sp_digit mp*/)
{ {
const sp_digit* m = p256_mod;
sp_digit mp = p256_mp_mod;
int i; int i;
sp_digit mu; sp_digit mu;
@ -359,7 +335,7 @@ static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp)
a[i+1] += a[i] >> 26; a[i+1] += a[i] >> 26;
a[i] &= 0x3ffffff; a[i] &= 0x3ffffff;
} }
else { else { /* Same code for explicit mp == 1 (which is always the case for P256) */
for (i = 0; i < 9; i++) { for (i = 0; i < 9; i++) {
mu = a[i] & 0x3ffffff; mu = a[i] & 0x3ffffff;
sp_256_mul_add_10(a+i, m, mu); sp_256_mul_add_10(a+i, m, mu);
@ -372,8 +348,12 @@ static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp)
} }
sp_256_mont_shift_10(a, a); sp_256_mont_shift_10(a, a);
//TODO: can below condition ever be true? Doesn't it require 512+th bit(s) in a to be set?
if ((a[9] >> 22) > 0) if ((a[9] >> 22) > 0)
{
dbg("THIS HAPPENS\n");
sp_256_sub_10(a, a, m); sp_256_sub_10(a, a, m);
}
sp_256_norm_10(a); sp_256_norm_10(a);
} }
@ -386,11 +366,14 @@ static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp)
* m Modulus (prime). * m Modulus (prime).
* mp Montogmery mulitplier. * mp Montogmery mulitplier.
*/ */
static void sp_256_mont_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b, static void sp_256_mont_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b
const sp_digit* m, sp_digit mp) /*, const sp_digit* m, sp_digit mp*/)
{ {
//const sp_digit* m = p256_mod;
//sp_digit mp = p256_mp_mod;
sp_256_mul_10(r, a, b); sp_256_mul_10(r, a, b);
sp_256_mont_reduce_10(r, m, mp); sp_256_mont_reduce_10(r /*, m, mp*/);
} }
/* Square the Montgomery form number. (r = a * a mod m) /* Square the Montgomery form number. (r = a * a mod m)
@ -400,11 +383,13 @@ static void sp_256_mont_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b
* m Modulus (prime). * m Modulus (prime).
* mp Montogmery mulitplier. * mp Montogmery mulitplier.
*/ */
static void sp_256_mont_sqr_10(sp_digit* r, const sp_digit* a, const sp_digit* m, static void sp_256_mont_sqr_10(sp_digit* r, const sp_digit* a
sp_digit mp) /*, const sp_digit* m, sp_digit mp*/)
{ {
sp_256_sqr_10(r, a); //const sp_digit* m = p256_mod;
sp_256_mont_reduce_10(r, m, mp); //sp_digit mp = p256_mp_mod;
sp_256_mont_mul_10(r, a, a /*, m, mp*/);
} }
/* Invert the number, in Montgomery form, modulo the modulus (prime) of the /* Invert the number, in Montgomery form, modulo the modulus (prime) of the
@ -432,10 +417,10 @@ static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a)
memcpy(t, a, sizeof(sp_digit) * 10); memcpy(t, a, sizeof(sp_digit) * 10);
for (i = 254; i >= 0; i--) { for (i = 254; i >= 0; i--) {
sp_256_mont_sqr_10(t, t, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t, t /*, p256_mod, p256_mp_mod*/);
/*if (p256_mod_2[i / 32] & ((sp_digit)1 << (i % 32)))*/ /*if (p256_mod_2[i / 32] & ((sp_digit)1 << (i % 32)))*/
if (i >= 224 || i == 192 || (i <= 95 && i != 1)) if (i >= 224 || i == 192 || (i <= 95 && i != 1))
sp_256_mont_mul_10(t, t, a, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t, t, a /*, p256_mod, p256_mp_mod*/);
} }
memcpy(r, t, sizeof(sp_digit) * 10); memcpy(r, t, sizeof(sp_digit) * 10);
} }
@ -577,22 +562,22 @@ static void sp_256_map_10(sp_point* r, sp_point* p)
sp_256_mont_inv_10(t1, p->z); sp_256_mont_inv_10(t1, p->z);
sp_256_mont_sqr_10(t2, t1, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t2, t1 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t1, t2, t1, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t1, t2, t1 /*, p256_mod, p256_mp_mod*/);
/* x /= z^2 */ /* x /= z^2 */
sp_256_mont_mul_10(r->x, p->x, t2, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->x, p->x, t2 /*, p256_mod, p256_mp_mod*/);
memset(r->x + 10, 0, sizeof(r->x) / 2); memset(r->x + 10, 0, sizeof(r->x) / 2);
sp_256_mont_reduce_10(r->x, p256_mod, p256_mp_mod); sp_256_mont_reduce_10(r->x /*, p256_mod, p256_mp_mod*/);
/* Reduce x to less than modulus */ /* Reduce x to less than modulus */
if (sp_256_cmp_10(r->x, p256_mod) >= 0) if (sp_256_cmp_10(r->x, p256_mod) >= 0)
sp_256_sub_10(r->x, r->x, p256_mod); sp_256_sub_10(r->x, r->x, p256_mod);
sp_256_norm_10(r->x); sp_256_norm_10(r->x);
/* y /= z^3 */ /* y /= z^3 */
sp_256_mont_mul_10(r->y, p->y, t1, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->y, p->y, t1 /*, p256_mod, p256_mp_mod*/);
memset(r->y + 10, 0, sizeof(r->y) / 2); memset(r->y + 10, 0, sizeof(r->y) / 2);
sp_256_mont_reduce_10(r->y, p256_mod, p256_mp_mod); sp_256_mont_reduce_10(r->y /*, p256_mod, p256_mp_mod*/);
/* Reduce y to less than modulus */ /* Reduce y to less than modulus */
if (sp_256_cmp_10(r->y, p256_mod) >= 0) if (sp_256_cmp_10(r->y, p256_mod) >= 0)
sp_256_sub_10(r->y, r->y, p256_mod); sp_256_sub_10(r->y, r->y, p256_mod);
@ -620,9 +605,9 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p)
return; return;
/* T1 = Z * Z */ /* T1 = Z * Z */
sp_256_mont_sqr_10(t1, r->z, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t1, r->z /*, p256_mod, p256_mp_mod*/);
/* Z = Y * Z */ /* Z = Y * Z */
sp_256_mont_mul_10(r->z, r->y, r->z, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->z, r->y, r->z /*, p256_mod, p256_mp_mod*/);
/* Z = 2Z */ /* Z = 2Z */
sp_256_mont_dbl_10(r->z, r->z, p256_mod); sp_256_mont_dbl_10(r->z, r->z, p256_mod);
/* T2 = X - T1 */ /* T2 = X - T1 */
@ -630,21 +615,21 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p)
/* T1 = X + T1 */ /* T1 = X + T1 */
sp_256_mont_add_10(t1, r->x, t1, p256_mod); sp_256_mont_add_10(t1, r->x, t1, p256_mod);
/* T2 = T1 * T2 */ /* T2 = T1 * T2 */
sp_256_mont_mul_10(t2, t1, t2, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t2, t1, t2 /*, p256_mod, p256_mp_mod*/);
/* T1 = 3T2 */ /* T1 = 3T2 */
sp_256_mont_tpl_10(t1, t2, p256_mod); sp_256_mont_tpl_10(t1, t2, p256_mod);
/* Y = 2Y */ /* Y = 2Y */
sp_256_mont_dbl_10(r->y, r->y, p256_mod); sp_256_mont_dbl_10(r->y, r->y, p256_mod);
/* Y = Y * Y */ /* Y = Y * Y */
sp_256_mont_sqr_10(r->y, r->y, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(r->y, r->y /*, p256_mod, p256_mp_mod*/);
/* T2 = Y * Y */ /* T2 = Y * Y */
sp_256_mont_sqr_10(t2, r->y, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t2, r->y /*, p256_mod, p256_mp_mod*/);
/* T2 = T2/2 */ /* T2 = T2/2 */
sp_256_div2_10(t2, t2, p256_mod); sp_256_div2_10(t2, t2, p256_mod);
/* Y = Y * X */ /* Y = Y * X */
sp_256_mont_mul_10(r->y, r->y, r->x, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->y, r->y, r->x /*, p256_mod, p256_mp_mod*/);
/* X = T1 * T1 */ /* X = T1 * T1 */
sp_256_mont_mul_10(r->x, t1, t1, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->x, t1, t1 /*, p256_mod, p256_mp_mod*/);
/* X = X - Y */ /* X = X - Y */
sp_256_mont_sub_10(r->x, r->x, r->y, p256_mod); sp_256_mont_sub_10(r->x, r->x, r->y, p256_mod);
/* X = X - Y */ /* X = X - Y */
@ -652,7 +637,7 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p)
/* Y = Y - X */ /* Y = Y - X */
sp_256_mont_sub_10(r->y, r->y, r->x, p256_mod); sp_256_mont_sub_10(r->y, r->y, r->x, p256_mod);
/* Y = Y * T1 */ /* Y = Y * T1 */
sp_256_mont_mul_10(r->y, r->y, t1, p256_mod, p256_mp_mod); sp_256_mont_mul_10(r->y, r->y, t1 /*, p256_mod, p256_mp_mod*/);
/* Y = Y - T2 */ /* Y = Y - T2 */
sp_256_mont_sub_10(r->y, r->y, t2, p256_mod); sp_256_mont_sub_10(r->y, r->y, t2, p256_mod);
} }
@ -700,36 +685,36 @@ static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q)
*r = p->infinity ? *q : *p; /* struct copy */ *r = p->infinity ? *q : *p; /* struct copy */
/* U1 = X1*Z2^2 */ /* U1 = X1*Z2^2 */
sp_256_mont_sqr_10(t1, q->z, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t1, q->z /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t3, t1, q->z, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t3, t1, q->z /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t1, t1, v->x, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t1, t1, v->x /*, p256_mod, p256_mp_mod*/);
/* U2 = X2*Z1^2 */ /* U2 = X2*Z1^2 */
sp_256_mont_sqr_10(t2, v->z, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t2, v->z /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t4, t2, v->z, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t4, t2, v->z /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t2, t2, q->x, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t2, t2, q->x /*, p256_mod, p256_mp_mod*/);
/* S1 = Y1*Z2^3 */ /* S1 = Y1*Z2^3 */
sp_256_mont_mul_10(t3, t3, v->y, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t3, t3, v->y /*, p256_mod, p256_mp_mod*/);
/* S2 = Y2*Z1^3 */ /* S2 = Y2*Z1^3 */
sp_256_mont_mul_10(t4, t4, q->y, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t4, t4, q->y /*, p256_mod, p256_mp_mod*/);
/* H = U2 - U1 */ /* H = U2 - U1 */
sp_256_mont_sub_10(t2, t2, t1, p256_mod); sp_256_mont_sub_10(t2, t2, t1, p256_mod);
/* R = S2 - S1 */ /* R = S2 - S1 */
sp_256_mont_sub_10(t4, t4, t3, p256_mod); sp_256_mont_sub_10(t4, t4, t3, p256_mod);
/* Z3 = H*Z1*Z2 */ /* Z3 = H*Z1*Z2 */
sp_256_mont_mul_10(v->z, v->z, q->z, p256_mod, p256_mp_mod); sp_256_mont_mul_10(v->z, v->z, q->z /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(v->z, v->z, t2, p256_mod, p256_mp_mod); sp_256_mont_mul_10(v->z, v->z, t2 /*, p256_mod, p256_mp_mod*/);
/* X3 = R^2 - H^3 - 2*U1*H^2 */ /* X3 = R^2 - H^3 - 2*U1*H^2 */
sp_256_mont_sqr_10(v->x, t4, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(v->x, t4 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_sqr_10(t5, t2, p256_mod, p256_mp_mod); sp_256_mont_sqr_10(t5, t2 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(v->y, t1, t5, p256_mod, p256_mp_mod); sp_256_mont_mul_10(v->y, t1, t5 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t5, t5, t2, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t5, t5, t2 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_sub_10(v->x, v->x, t5, p256_mod); sp_256_mont_sub_10(v->x, v->x, t5, p256_mod);
sp_256_mont_dbl_10(t1, v->y, p256_mod); sp_256_mont_dbl_10(t1, v->y, p256_mod);
sp_256_mont_sub_10(v->x, v->x, t1, p256_mod); sp_256_mont_sub_10(v->x, v->x, t1, p256_mod);
/* Y3 = R*(U1*H^2 - X3) - S1*H^3 */ /* Y3 = R*(U1*H^2 - X3) - S1*H^3 */
sp_256_mont_sub_10(v->y, v->y, v->x, p256_mod); sp_256_mont_sub_10(v->y, v->y, v->x, p256_mod);
sp_256_mont_mul_10(v->y, v->y, t4, p256_mod, p256_mp_mod); sp_256_mont_mul_10(v->y, v->y, t4 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_10(t5, t5, t3, p256_mod, p256_mp_mod); sp_256_mont_mul_10(t5, t5, t3 /*, p256_mod, p256_mp_mod*/);
sp_256_mont_sub_10(v->y, v->y, t5, p256_mod); sp_256_mont_sub_10(v->y, v->y, t5, p256_mod);
} }
} }