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tls: P256 code shrink

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function                                             old     new   delta
sp_256_to_bin_10                                       -     120    +120
sp_256_from_bin_10                                     -     119    +119
sp_256_proj_point_dbl_10                             446     443      -3
curve_P256_compute_pubkey_and_premaster              191     186      -5
sp_256_point_from_bin2x32                             62      50     -12
sp_256_to_bin                                        120       -    -120
static.sp_256_from_bin                               149       -    -149
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 0/3 up/down: 239/-289)          Total: -50 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-05 13:30:48 +02:00
parent 934bb01d51
commit e730505034
1 changed files with 42 additions and 52 deletions
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94
networking/tls_sp_c32.c
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@ -80,13 +80,13 @@ static void sp_256_norm_10(sp_digit* a)
} }
} }
/* Write r as big endian to byte aray. /* Write r as big endian to byte array.
* Fixed length number of bytes written: 32 * Fixed length number of bytes written: 32
* *
* r A single precision integer. * r A single precision integer.
* a Byte array. * a Byte array.
*/ */
static void sp_256_to_bin(sp_digit* r, uint8_t* a) static void sp_256_to_bin_10(sp_digit* r, uint8_t* a)
{ {
int i, j, s = 0, b; int i, j, s = 0, b;
@ -112,33 +112,28 @@ static void sp_256_to_bin(sp_digit* r, uint8_t* a)
} }
} }
/* Read big endian unsigned byte aray into r. /* Read big endian unsigned byte array into r.
* *
* r A single precision integer. * r A single precision integer.
* a Byte array. * a Byte array.
* n Number of bytes in array to read. * n Number of bytes in array to read.
*/ */
static void sp_256_from_bin(sp_digit* r, int max, const uint8_t* a, int n) static void sp_256_from_bin_10(sp_digit* r, const uint8_t* a)
{ {
int i, j = 0, s = 0; int i, j = 0, s = 0;
r[0] = 0; r[0] = 0;
for (i = n-1; i >= 0; i--) { for (i = 32 - 1; i >= 0; i--) {
r[j] |= ((sp_digit)a[i]) << s; r[j] |= ((sp_digit)a[i]) << s;
if (s >= 18) { if (s >= 18) {
r[j] &= 0x3ffffff; r[j] &= 0x3ffffff;
s = 26 - s; s = 26 - s;
if (j + 1 >= max)
break;
r[++j] = a[i] >> s; r[++j] = a[i] >> s;
s = 8 - s; s = 8 - s;
} }
else else
s += 8; s += 8;
} }
for (j++; j < max; j++)
r[j] = 0;
} }
/* Convert a point of big-endian 32-byte x,y pair to type sp_point. */ /* Convert a point of big-endian 32-byte x,y pair to type sp_point. */
@ -146,11 +141,9 @@ static void sp_256_point_from_bin2x32(sp_point* p, const uint8_t *bin2x32)
{ {
memset(p, 0, sizeof(*p)); memset(p, 0, sizeof(*p));
/*p->infinity = 0;*/ /*p->infinity = 0;*/
sp_256_from_bin(p->x, 2 * 10, bin2x32, 32); sp_256_from_bin_10(p->x, bin2x32);
sp_256_from_bin(p->y, 2 * 10, bin2x32 + 32, 32); sp_256_from_bin_10(p->y, bin2x32 + 32);
//static const uint8_t one[1] = { 1 }; p->z[0] = 1; /* p->z = 1 */
//sp_256_from_bin(p->z, 2 * 10, one, 1);
p->z[0] = 1;
} }
/* Compare a with b. /* Compare a with b.
@ -195,30 +188,6 @@ static void sp_256_sub_10(sp_digit* r, const sp_digit* a, const sp_digit* b)
r[i] = a[i] - b[i]; r[i] = a[i] - b[i];
} }
/* Shift number left one bit. Bottom bit is lost. */
static void sp_256_rshift1_10(sp_digit* r, sp_digit* a)
{
int i;
for (i = 0; i < 9; i++)
r[i] = ((a[i] >> 1) | (a[i + 1] << 25)) & 0x3ffffff;
r[9] = a[9] >> 1;
}
/* Mul a by scalar b and add into r. (r += a * b) */
static void sp_256_mul_add_10(sp_digit* r, const sp_digit* a, sp_digit b)
{
int64_t tb = b;
int64_t t = 0;
int i;
for (i = 0; i < 10; i++) {
t += (tb * a[i]) + r[i];
r[i] = t & 0x3ffffff;
t >>= 26;
}
r[10] += t;
}
/* Multiply a and b into r. (r = a * b) */ /* Multiply a and b into r. (r = a * b) */
static void sp_256_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b) static void sp_256_mul_10(sp_digit* r, const sp_digit* a, const sp_digit* b)
{ {
@ -271,6 +240,15 @@ static void sp_256_sqr_10(sp_digit* r, const sp_digit* a)
r[0] = (sp_digit)(c >> 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)
{
int i;
for (i = 0; i < 9; i++)
r[i] = ((a[i] >> 1) | (a[i + 1] << 25)) & 0x3ffffff;
r[9] = a[9] >> 1;
}
/* Divide the number by 2 mod the modulus (prime). (r = a / 2 % m) */ /* Divide the number by 2 mod the modulus (prime). (r = a / 2 % m) */
static void sp_256_div2_10(sp_digit* r, const sp_digit* a, const sp_digit* m) static void sp_256_div2_10(sp_digit* r, const sp_digit* a, const sp_digit* m)
{ {
@ -345,6 +323,20 @@ static void sp_256_mont_shift_10(sp_digit* r, const sp_digit* a)
memset(&r[10], 0, sizeof(*r) * 10); memset(&r[10], 0, sizeof(*r) * 10);
} }
/* Mul a by scalar b and add into r. (r += a * b) */
static void sp_256_mul_add_10(sp_digit* r, const sp_digit* a, sp_digit b)
{
int64_t t = 0;
int i;
for (i = 0; i < 10; i++) {
t += ((int64_t)b * a[i]) + r[i];
r[i] = t & 0x3ffffff;
t >>= 26;
}
r[10] += t;
}
/* Reduce the number back to 256 bits using Montgomery reduction. /* Reduce the number back to 256 bits using Montgomery reduction.
* *
* a A single precision number to reduce in place. * a A single precision number to reduce in place.
@ -362,7 +354,7 @@ static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp)
sp_256_mul_add_10(a+i, m, mu); sp_256_mul_add_10(a+i, m, mu);
a[i+1] += a[i] >> 26; a[i+1] += a[i] >> 26;
} }
mu = (a[i] * mp) & 0x3fffffl; mu = (a[i] * mp) & 0x03fffff;
sp_256_mul_add_10(a+i, m, mu); sp_256_mul_add_10(a+i, m, mu);
a[i+1] += a[i] >> 26; a[i+1] += a[i] >> 26;
a[i] &= 0x3ffffff; a[i] &= 0x3ffffff;
@ -370,11 +362,11 @@ static void sp_256_mont_reduce_10(sp_digit* a, const sp_digit* m, sp_digit mp)
else { else {
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, p256_mod, mu); sp_256_mul_add_10(a+i, m, mu);
a[i+1] += a[i] >> 26; a[i+1] += a[i] >> 26;
} }
mu = a[i] & 0x3fffffl; mu = a[i] & 0x03fffff;
sp_256_mul_add_10(a+i, p256_mod, mu); sp_256_mul_add_10(a+i, m, mu);
a[i+1] += a[i] >> 26; a[i+1] += a[i] >> 26;
a[i] &= 0x3ffffff; a[i] &= 0x3ffffff;
} }
@ -617,7 +609,6 @@ static void sp_256_map_10(sp_point* r, sp_point* p)
*/ */
static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p) static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p)
{ {
sp_point tp;
sp_digit t1[2*10]; sp_digit t1[2*10];
sp_digit t2[2*10]; sp_digit t2[2*10];
@ -625,10 +616,9 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p)
if (r != p) if (r != p)
*r = *p; /* struct copy */ *r = *p; /* struct copy */
if (r->infinity) { if (r->infinity) /* If infinity, don't double */
/* If infinity, don't double (work on dummy value) */ return;
r = &tp;
}
/* 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 */
@ -848,7 +838,7 @@ static void sp_ecc_secret_gen_256(const sp_digit priv[10], const uint8_t *pub2x3
sp_256_ecc_mulmod_10(point, point, priv); sp_256_ecc_mulmod_10(point, point, priv);
sp_256_to_bin(point->x, out32); sp_256_to_bin_10(point->x, out32);
dump_hex("out32: %s\n", out32, 32); dump_hex("out32: %s\n", out32, 32);
} }
@ -876,7 +866,7 @@ static void sp_256_ecc_gen_k_10(sp_digit k[10])
#if FIXED_SECRET #if FIXED_SECRET
memset(buf, 0x77, sizeof(buf)); memset(buf, 0x77, sizeof(buf));
#endif #endif
sp_256_from_bin(k, 10, buf, sizeof(buf)); sp_256_from_bin_10(k, buf);
#if !SIMPLIFY #if !SIMPLIFY
if (sp_256_cmp_10(k, p256_order2) < 0) if (sp_256_cmp_10(k, p256_order2) < 0)
break; break;
@ -901,8 +891,8 @@ static void sp_ecc_make_key_256(sp_digit privkey[10], uint8_t *pubkey)
sp_256_ecc_gen_k_10(privkey); sp_256_ecc_gen_k_10(privkey);
sp_256_ecc_mulmod_base_10(point, privkey); sp_256_ecc_mulmod_base_10(point, privkey);
sp_256_to_bin(point->x, pubkey); sp_256_to_bin_10(point->x, pubkey);
sp_256_to_bin(point->y, pubkey + 32); sp_256_to_bin_10(point->y, pubkey + 32);
memset(point, 0, sizeof(point)); //paranoia memset(point, 0, sizeof(point)); //paranoia
} }