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secp256k1
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Support for 32-bit limbs in field_gmp

This commit is contained in:
Pieter Wuille 2013-04-06 22:31:02 +02:00
parent 7a4b7691b6
commit 6baf08dfe4
4 changed files with 56 additions and 23 deletions
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2
src/impl/field.h
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@ -146,6 +146,7 @@ void static secp256k1_fe_start(void) {
0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F
};
if (secp256k1_fe_consts == NULL) {
secp256k1_fe_inner_start();
secp256k1_fe_consts_t *ret = (secp256k1_fe_consts_t*)malloc(sizeof(secp256k1_fe_t));
secp256k1_num_init(&ret->p);
secp256k1_num_set_bin(&ret->p, secp256k1_fe_consts_p, sizeof(secp256k1_fe_consts_p));
@ -159,6 +160,7 @@ void static secp256k1_fe_stop(void) {
secp256k1_num_free(&c->p);
free((void*)c);
secp256k1_fe_consts = NULL;
secp256k1_fe_inner_stop();
}
}

3
src/impl/field_10x26.h
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@ -7,6 +7,9 @@
#include "../num.h"
#include "../field.h"
void static secp256k1_fe_inner_start(void) {}
void static secp256k1_fe_inner_stop(void) {}
void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
// fog("normalize in: ", r);
uint32_t c;

3
src/impl/field_5x52.h
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@ -20,6 +20,9 @@
* output.
*/
void static secp256k1_fe_inner_start(void) {}
void static secp256k1_fe_inner_stop(void) {}
void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
uint64_t c;
c = r->n[0];

65
src/impl/field_gmp.h
View File

@ -7,25 +7,38 @@
#include "../num.h"
#include "../field.h"
static mp_limb_t secp256k1_field_p[FIELD_LIMBS];
static mp_limb_t secp256k1_field_pc[(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS];
void static secp256k1_fe_inner_start(void) {
for (int i=0; i<(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS; i++)
secp256k1_field_pc[i] = 0;
secp256k1_field_pc[0] += 0x3D1UL;
secp256k1_field_pc[32/GMP_NUMB_BITS] += (1UL << (32 % GMP_NUMB_BITS));
for (int i=0; i<FIELD_LIMBS; i++) {
secp256k1_field_p[i] = 0;
}
mpn_sub(secp256k1_field_p, secp256k1_field_p, FIELD_LIMBS, secp256k1_field_pc, (33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS);
}
void static secp256k1_fe_inner_stop(void) {
}
void static secp256k1_fe_normalize(secp256k1_fe_t *r) {
if (r->n[FIELD_LIMBS] != 0) {
#if (GMP_NUMB_BITS >= 40)
if (r->n[FIELD_LIMBS] == 0)
return;
mp_limb_t carry = mpn_add_1(r->n, r->n, FIELD_LIMBS, 0x1000003D1ULL * r->n[FIELD_LIMBS]);
mpn_add_1(r->n, r->n, FIELD_LIMBS, 0x1000003D1ULL * carry);
r->n[FIELD_LIMBS] = 0;
int overflow = 1;
for (int i=FIELD_LIMBS-1; i>0; i--)
overflow &= (r->n[i] == GMP_NUMB_MASK);
overflow &= (r->n[0] >= GMP_NUMB_MASK - 0x1000003D0ULL);
if (overflow) {
for (int i=FIELD_LIMBS-1; i>0; i--)
r->n[i] = 0;
r->n[0] -= (GMP_NUMB_MASK - 0x1000003D0ULL);
}
#else
# error "GMP_NUMB_BITS too low"
mp_limb_t carry = mpn_add_1(r->n, r->n, FIELD_LIMBS, 0x3D1UL * r->n[FIELD_LIMBS]) +
mpn_add_1(r->n+(32/GMP_NUMB_BITS), r->n+(32/GMP_NUMB_BITS), FIELD_LIMBS-(32/GMP_NUMB_BITS), r->n[FIELD_LIMBS] << (32 % GMP_NUMB_BITS));
mpn_add_1(r->n, r->n, FIELD_LIMBS, 0x3D1UL * carry);
mpn_add_1(r->n+(32/GMP_NUMB_BITS), r->n+(32/GMP_NUMB_BITS), FIELD_LIMBS-(32/GMP_NUMB_BITS), carry << (32%GMP_NUMB_BITS));
#endif
r->n[FIELD_LIMBS] = 0;
}
if (mpn_cmp(r->n, secp256k1_field_p, FIELD_LIMBS) >= 0)
mpn_sub(r->n, r->n, FIELD_LIMBS, secp256k1_field_p, FIELD_LIMBS);
}
void static inline secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
@ -34,7 +47,6 @@ void static inline secp256k1_fe_set_int(secp256k1_fe_t *r, int a) {
r->n[i] = 0;
}
// TODO: not constant time!
int static inline secp256k1_fe_is_zero(const secp256k1_fe_t *a) {
int ret = 1;
for (int i=0; i<FIELD_LIMBS+1; i++)
@ -46,7 +58,6 @@ int static inline secp256k1_fe_is_odd(const secp256k1_fe_t *a) {
return a->n[0] & 1;
}
// TODO: not constant time!
int static inline secp256k1_fe_equal(const secp256k1_fe_t *a, const secp256k1_fe_t *b) {
int ret = 1;
for (int i=0; i<FIELD_LIMBS+1; i++)
@ -86,7 +97,7 @@ void static inline secp256k1_fe_negate(secp256k1_fe_t *r, const secp256k1_fe_t *
mpn_sub_1(r->n, r->n, FIELD_LIMBS, 0x1000003D0ULL);
#else
mpn_sub_1(r->n, r->n, FIELD_LIMBS, 0x3D0UL);
mpn_sub_1(r->n+1, r->n+1, FIELD_LIMBS-1, 0x1);
mpn_sub_1(r->n+(32/GMP_NUMB_BITS), r->n+(32/GMP_NUMB_BITS), FIELD_LIMBS-(32/GMP_NUMB_BITS), 0x1UL << (32%GMP_NUMB_BITS));
#endif
}
@ -99,10 +110,24 @@ void static inline secp256k1_fe_add(secp256k1_fe_t *r, const secp256k1_fe_t *a)
}
void static secp256k1_fe_reduce(secp256k1_fe_t *r, mp_limb_t *tmp) {
mp_limb_t o = mpn_addmul_1(tmp, tmp+FIELD_LIMBS, FIELD_LIMBS, 0x1000003D1);
mp_limb_t q[2];
q[1] = mpn_mul_1(q, &o, 1, 0x1000003D1);
r->n[FIELD_LIMBS] = mpn_add(r->n, tmp, FIELD_LIMBS, q, 2);
// <A1 A2 A3 A4> <B1 B2 B3 B4>
// B1 B2 B3 B4
// + C * A1 A2 A3 A4
// + A1 A2 A3 A4
#if (GMP_NUMB_BITS >= 33)
mp_limb_t o = mpn_addmul_1(tmp, tmp+FIELD_LIMBS, FIELD_LIMBS, 0x1000003D1ULL);
#else
mp_limb_t o = mpn_addmul_1(tmp, tmp+FIELD_LIMBS, FIELD_LIMBS, 0x3D1UL) +
mpn_addmul_1(tmp+(32/GMP_NUMB_BITS), tmp+FIELD_LIMBS, FIELD_LIMBS-(32/GMP_NUMB_BITS), 0x1UL << (32%GMP_NUMB_BITS));
#endif
mp_limb_t q[1+(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS];
q[(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS] = mpn_mul_1(q, secp256k1_field_pc, (33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS, o);
#if (GMP_NUMB_BITS <= 32)
mp_limb_t o2 = tmp[2*FIELD_LIMBS-(32/GMP_NUMB_BITS)] << (32%GMP_NUMB_BITS);
q[(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS] += mpn_addmul_1(q, secp256k1_field_pc, (33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS, o2);
#endif
r->n[FIELD_LIMBS] = mpn_add(r->n, tmp, FIELD_LIMBS, q, 1+(33+GMP_NUMB_BITS-1)/GMP_NUMB_BITS);
}
void static secp256k1_fe_mul(secp256k1_fe_t *r, const secp256k1_fe_t *a, const secp256k1_fe_t *b) {