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Refactor of the ecc_projective_add_point and ecc_projective_dbl_point functions to eliminate duplicate versions. Modified new single functions to work with normal, fast and alt_ecc_size math options. Careful use of mp_clear to retain original performance.

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This commit is contained in:
David Garske
2016-05-05 19:00:50 -07:00
parent fe58db2a07
commit 880b2e454b
1 changed files with 150 additions and 404 deletions
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554
wolfcrypt/src/ecc.c
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@ -268,311 +268,6 @@ static mp_digit get_digit(mp_int* a, int n)
}
#if defined(USE_FAST_MATH)
/* fast math accelerated version, but not for fp ecc yet */
/**
Add two ECC points
P The point to add
Q The point to add
R [out] The destination of the double
modulus The modulus of the field the ECC curve is in
mp The "b" value from montgomery_setup()
return MP_OKAY on success
*/
int ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R,
mp_int* modulus, mp_digit* mp)
{
fp_int t1, t2, x, y, z;
int err;
if (P == NULL || Q == NULL || R == NULL || modulus == NULL || mp == NULL)
return ECC_BAD_ARG_E;
if ((err = mp_init_multi(&t1, &t2, &x, &y, &z, NULL)) != MP_OKAY) {
return err;
}
/* should we dbl instead? */
fp_sub(modulus, Q->y, &t1);
if ( (fp_cmp(P->x, Q->x) == FP_EQ) &&
(get_digit_count(Q->z) && fp_cmp(P->z, Q->z) == FP_EQ) &&
(fp_cmp(P->y, Q->y) == FP_EQ || fp_cmp(P->y, &t1) == FP_EQ))
{
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return ecc_projective_dbl_point(P, R, modulus, mp);
}
fp_copy(P->x, &x);
fp_copy(P->y, &y);
fp_copy(P->z, &z);
/* if Z is one then these are no-operations */
if (get_digit_count(Q->z)) {
/* T1 = Z' * Z' */
fp_sqr(Q->z, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* X = X * T1 */
fp_mul(&t1, &x, &x);
fp_montgomery_reduce(&x, modulus, *mp);
/* T1 = Z' * T1 */
fp_mul(Q->z, &t1, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* Y = Y * T1 */
fp_mul(&t1, &y, &y);
fp_montgomery_reduce(&y, modulus, *mp);
}
/* T1 = Z*Z */
fp_sqr(&z, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* T2 = X' * T1 */
fp_mul(Q->x, &t1, &t2);
fp_montgomery_reduce(&t2, modulus, *mp);
/* T1 = Z * T1 */
fp_mul(&z, &t1, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* T1 = Y' * T1 */
fp_mul(Q->y, &t1, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* Y = Y - T1 */
fp_sub(&y, &t1, &y);
if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(&y, modulus, &y);
}
/* T1 = 2T1 */
fp_add(&t1, &t1, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1);
}
/* T1 = Y + T1 */
fp_add(&t1, &y, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1);
}
/* X = X - T2 */
fp_sub(&x, &t2, &x);
if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(&x, modulus, &x);
}
/* T2 = 2T2 */
fp_add(&t2, &t2, &t2);
if (fp_cmp(&t2, modulus) != FP_LT) {
fp_sub(&t2, modulus, &t2);
}
/* T2 = X + T2 */
fp_add(&t2, &x, &t2);
if (fp_cmp(&t2, modulus) != FP_LT) {
fp_sub(&t2, modulus, &t2);
}
/* if Z' != 1 */
if (get_digit_count(Q->z)) {
/* Z = Z * Z' */
fp_mul(&z, Q->z, &z);
fp_montgomery_reduce(&z, modulus, *mp);
}
/* Z = Z * X */
fp_mul(&z, &x, &z);
fp_montgomery_reduce(&z, modulus, *mp);
/* T1 = T1 * X */
fp_mul(&t1, &x, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* X = X * X */
fp_sqr(&x, &x);
fp_montgomery_reduce(&x, modulus, *mp);
/* T2 = T2 * x */
fp_mul(&t2, &x, &t2);
fp_montgomery_reduce(&t2, modulus, *mp);
/* T1 = T1 * X */
fp_mul(&t1, &x, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* X = Y*Y */
fp_sqr(&y, &x);
fp_montgomery_reduce(&x, modulus, *mp);
/* X = X - T2 */
fp_sub(&x, &t2, &x);
if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(&x, modulus, &x);
}
/* T2 = T2 - X */
fp_sub(&t2, &x, &t2);
if (fp_cmp_d(&t2, 0) == FP_LT) {
fp_add(&t2, modulus, &t2);
}
/* T2 = T2 - X */
fp_sub(&t2, &x, &t2);
if (fp_cmp_d(&t2, 0) == FP_LT) {
fp_add(&t2, modulus, &t2);
}
/* T2 = T2 * Y */
fp_mul(&t2, &y, &t2);
fp_montgomery_reduce(&t2, modulus, *mp);
/* Y = T2 - T1 */
fp_sub(&t2, &t1, &y);
if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(&y, modulus, &y);
}
/* Y = Y/2 */
if (fp_isodd(&y)) {
fp_add(&y, modulus, &y);
}
fp_div_2(&y, &y);
/* return result */
fp_copy(&x, R->x);
fp_copy(&y, R->y);
fp_copy(&z, R->z);
/* clear stack variables */
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return MP_OKAY;
}
/**
Double an ECC point
P The point to double
R [out] The destination of the double
modulus The modulus of the field the ECC curve is in
mp The "b" value from montgomery_setup()
return MP_OKAY on success
*/
int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
mp_digit* mp)
{
fp_int x, y, z, t1, t2;
int err;
if (P == NULL || R == NULL || modulus == NULL || mp == NULL)
return ECC_BAD_ARG_E;
if ((err = mp_init_multi(&x, &y, &z, &t1, &t2, NULL)) != MP_OKAY) {
return err;
}
/* Use local due to possible insufficient size of alt_ecc_size in ecc_point x,y,z */
fp_copy(P->x, &x);
fp_copy(P->y, &y);
fp_copy(P->z, &z);
/* T1 = Z * Z */
fp_sqr(&z, &t1);
fp_montgomery_reduce(&t1, modulus, *mp);
/* Z = Y * Z */
fp_mul(&z, &y, &z);
fp_montgomery_reduce(&z, modulus, *mp);
/* Z = 2Z */
fp_add(&z, &z, &z);
if (fp_cmp(&z, modulus) != FP_LT) {
fp_sub(&z, modulus, &z);
}
/* T2 = X - T1 */
fp_sub(&x, &t1, &t2);
if (fp_cmp_d(&t2, 0) == FP_LT) {
fp_add(&t2, modulus, &t2);
}
/* T1 = X + T1 */
fp_add(&t1, &x, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1);
}
/* T2 = T1 * T2 */
fp_mul(&t1, &t2, &t2);
fp_montgomery_reduce(&t2, modulus, *mp);
/* T1 = 2T2 */
fp_add(&t2, &t2, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1);
}
/* T1 = T1 + T2 */
fp_add(&t1, &t2, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1);
}
/* Y = 2Y */
fp_add(&y, &y, &y);
if (fp_cmp(&y, modulus) != FP_LT) {
fp_sub(&y, modulus, &y);
}
/* Y = Y * Y */
fp_sqr(&y, &y);
fp_montgomery_reduce(&y, modulus, *mp);
/* T2 = Y * Y */
fp_sqr(&y, &t2);
fp_montgomery_reduce(&t2, modulus, *mp);
/* T2 = T2/2 */
if (fp_isodd(&t2)) {
fp_add(&t2, modulus, &t2);
}
fp_div_2(&t2, &t2);
/* Y = Y * X */
fp_mul(&y, &x, &y);
fp_montgomery_reduce(&y, modulus, *mp);
/* X = T1 * T1 */
fp_sqr(&t1, &x);
fp_montgomery_reduce(&x, modulus, *mp);
/* X = X - Y */
fp_sub(&x, &y, &x);
if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(&x, modulus, &x);
}
/* X = X - Y */
fp_sub(&x, &y, &x);
if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(&x, modulus, &x);
}
/* Y = Y - X */
fp_sub(&y, &x, &y);
if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(&y, modulus, &y);
}
/* Y = Y * T1 */
fp_mul(&y, &t1, &y);
fp_montgomery_reduce(&y, modulus, *mp);
/* Y = Y - T2 */
fp_sub(&y, &t2, &y);
if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(&y, modulus, &y);
}
/* Return x, y, and z */
fp_copy(&x, R->x);
fp_copy(&y, R->y);
fp_copy(&z, R->z);
/* Clear used locals */
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return MP_OKAY;
}
#else /* USE_FAST_MATH */
/**
Add two ECC points
P The point to add
@ -585,43 +280,63 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
mp_int* modulus, mp_digit* mp)
{
mp_int t1;
mp_int t2;
mp_int x;
mp_int y;
mp_int z;
mp_int t1, t2;
#ifdef ALT_ECC_SIZE
mp_int rx, ry, rz;
#endif
mp_int *x, *y, *z;
int err;
if (P == NULL || Q == NULL || R == NULL || modulus == NULL || mp == NULL)
return ECC_BAD_ARG_E;
if ((err = mp_init_multi(&t1, &t2, &x, &y, &z, NULL)) != MP_OKAY) {
if ((err = mp_init_multi(&t1, &t2, NULL, NULL, NULL, NULL)) != MP_OKAY) {
return err;
}
/* should we dbl instead? */
err = mp_sub(modulus, Q->y, &t1);
if (err == MP_OKAY)
err = mp_sub(modulus, Q->y, &t1);
if (err == MP_OKAY) {
if ( (mp_cmp(P->x, Q->x) == MP_EQ) &&
(get_digit_count(Q->z) && mp_cmp(P->z, Q->z) == MP_EQ) &&
(mp_cmp(P->y, Q->y) == MP_EQ || mp_cmp(P->y, &t1) == MP_EQ)) {
mp_clear(&t1);
mp_clear(&t2);
mp_clear(&x);
mp_clear(&y);
mp_clear(&z);
return ecc_projective_dbl_point(P, R, modulus, mp);
}
}
if (err != MP_OKAY) {
mp_clear(&t1);
mp_clear(&t2);
return err;
}
#ifdef ALT_ECC_SIZE
/* Use local stack variable */
x = ℞
y = &ry;
z = &rz;
if ((err = mp_init_multi(x, y, z, NULL, NULL, NULL)) != MP_OKAY) {
mp_clear(&t1);
mp_clear(&t2);
return err;
}
#else
/* Use destination directly */
x = R->x;
y = R->y;
z = R->z;
#endif
if (err == MP_OKAY)
err = mp_copy(P->x, &x);
err = mp_copy(P->x, x);
if (err == MP_OKAY)
err = mp_copy(P->y, &y);
err = mp_copy(P->y, y);
if (err == MP_OKAY)
err = mp_copy(P->z, &z);
err = mp_copy(P->z, z);
/* if Z is one then these are no-operations */
if (err == MP_OKAY) {
@ -633,9 +348,9 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
/* X = X * T1 */
if (err == MP_OKAY)
err = mp_mul(&t1, &x, &x);
err = mp_mul(&t1, x, x);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&x, modulus, *mp);
err = mp_montgomery_reduce(x, modulus, *mp);
/* T1 = Z' * T1 */
if (err == MP_OKAY)
@ -645,15 +360,15 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
/* Y = Y * T1 */
if (err == MP_OKAY)
err = mp_mul(&t1, &y, &y);
err = mp_mul(&t1, y, y);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&y, modulus, *mp);
err = mp_montgomery_reduce(y, modulus, *mp);
}
}
/* T1 = Z*Z */
if (err == MP_OKAY)
err = mp_sqr(&z, &t1);
err = mp_sqr(z, &t1);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t1, modulus, *mp);
@ -665,7 +380,7 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
/* T1 = Z * T1 */
if (err == MP_OKAY)
err = mp_mul(&z, &t1, &t1);
err = mp_mul(z, &t1, &t1);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t1, modulus, *mp);
@ -677,10 +392,10 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
/* Y = Y - T1 */
if (err == MP_OKAY)
err = mp_sub(&y, &t1, &y);
err = mp_sub(y, &t1, y);
if (err == MP_OKAY) {
if (mp_cmp_d(&y, 0) == MP_LT)
err = mp_add(&y, modulus, &y);
if (mp_cmp_d(y, 0) == MP_LT)
err = mp_add(y, modulus, y);
}
/* T1 = 2T1 */
if (err == MP_OKAY)
@ -691,17 +406,17 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
}
/* T1 = Y + T1 */
if (err == MP_OKAY)
err = mp_add(&t1, &y, &t1);
err = mp_add(&t1, y, &t1);
if (err == MP_OKAY) {
if (mp_cmp(&t1, modulus) != MP_LT)
err = mp_sub(&t1, modulus, &t1);
}
/* X = X - T2 */
if (err == MP_OKAY)
err = mp_sub(&x, &t2, &x);
err = mp_sub(x, &t2, x);
if (err == MP_OKAY) {
if (mp_cmp_d(&x, 0) == MP_LT)
err = mp_add(&x, modulus, &x);
if (mp_cmp_d(x, 0) == MP_LT)
err = mp_add(x, modulus, x);
}
/* T2 = 2T2 */
if (err == MP_OKAY)
@ -712,7 +427,7 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
}
/* T2 = X + T2 */
if (err == MP_OKAY)
err = mp_add(&t2, &x, &t2);
err = mp_add(&t2, x, &t2);
if (err == MP_OKAY) {
if (mp_cmp(&t2, modulus) != MP_LT)
err = mp_sub(&t2, modulus, &t2);
@ -721,103 +436,104 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
if (err == MP_OKAY) {
if (get_digit_count(Q->z)) {
/* Z = Z * Z' */
err = mp_mul(&z, Q->z, &z);
err = mp_mul(z, Q->z, z);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&z, modulus, *mp);
err = mp_montgomery_reduce(z, modulus, *mp);
}
}
/* Z = Z * X */
if (err == MP_OKAY)
err = mp_mul(&z, &x, &z);
err = mp_mul(z, x, z);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&z, modulus, *mp);
err = mp_montgomery_reduce(z, modulus, *mp);
/* T1 = T1 * X */
if (err == MP_OKAY)
err = mp_mul(&t1, &x, &t1);
err = mp_mul(&t1, x, &t1);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t1, modulus, *mp);
/* X = X * X */
if (err == MP_OKAY)
err = mp_sqr(&x, &x);
err = mp_sqr(x, x);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&x, modulus, *mp);
err = mp_montgomery_reduce(x, modulus, *mp);
/* T2 = T2 * x */
if (err == MP_OKAY)
err = mp_mul(&t2, &x, &t2);
err = mp_mul(&t2, x, &t2);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t2, modulus, *mp);
/* T1 = T1 * X */
if (err == MP_OKAY)
err = mp_mul(&t1, &x, &t1);
err = mp_mul(&t1, x, &t1);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t1, modulus, *mp);
/* X = Y*Y */
if (err == MP_OKAY)
err = mp_sqr(&y, &x);
err = mp_sqr(y, x);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&x, modulus, *mp);
err = mp_montgomery_reduce(x, modulus, *mp);
/* X = X - T2 */
if (err == MP_OKAY)
err = mp_sub(&x, &t2, &x);
err = mp_sub(x, &t2, x);
if (err == MP_OKAY) {
if (mp_cmp_d(&x, 0) == MP_LT)
err = mp_add(&x, modulus, &x);
if (mp_cmp_d(x, 0) == MP_LT)
err = mp_add(x, modulus, x);
}
/* T2 = T2 - X */
if (err == MP_OKAY)
err = mp_sub(&t2, &x, &t2);
err = mp_sub(&t2, x, &t2);
if (err == MP_OKAY) {
if (mp_cmp_d(&t2, 0) == MP_LT)
err = mp_add(&t2, modulus, &t2);
}
/* T2 = T2 - X */
if (err == MP_OKAY)
err = mp_sub(&t2, &x, &t2);
err = mp_sub(&t2, x, &t2);
if (err == MP_OKAY) {
if (mp_cmp_d(&t2, 0) == MP_LT)
err = mp_add(&t2, modulus, &t2);
}
/* T2 = T2 * Y */
if (err == MP_OKAY)
err = mp_mul(&t2, &y, &t2);
err = mp_mul(&t2, y, &t2);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t2, modulus, *mp);
/* Y = T2 - T1 */
if (err == MP_OKAY)
err = mp_sub(&t2, &t1, &y);
err = mp_sub(&t2, &t1, y);
if (err == MP_OKAY) {
if (mp_cmp_d(&y, 0) == MP_LT)
err = mp_add(&y, modulus, &y);
if (mp_cmp_d(y, 0) == MP_LT)
err = mp_add(y, modulus, y);
}
/* Y = Y/2 */
if (err == MP_OKAY) {
if (mp_isodd(&y))
err = mp_add(&y, modulus, &y);
if (mp_isodd(y))
err = mp_add(y, modulus, y);
}
if (err == MP_OKAY)
err = mp_div_2(&y, &y);
err = mp_div_2(y, y);
#ifdef ALT_ECC_SIZE
if (err == MP_OKAY)
err = mp_copy(&x, R->x);
err = mp_copy(x, R->x);
if (err == MP_OKAY)
err = mp_copy(&y, R->y);
err = mp_copy(y, R->y);
if (err == MP_OKAY)
err = mp_copy(&z, R->z);
err = mp_copy(z, R->z);
#endif
#ifndef USE_FAST_MATH
/* clean up */
mp_clear(&t1);
mp_clear(&t2);
mp_clear(&x);
mp_clear(&y);
mp_clear(&z);
#endif
return err;
}
@ -834,8 +550,11 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
mp_digit* mp)
{
mp_int t1;
mp_int t2;
mp_int t1, t2;
#ifdef ALT_ECC_SIZE
mp_int rx, ry, rz;
#endif
mp_int *x, *y, *z;
int err;
if (P == NULL || R == NULL || modulus == NULL || mp == NULL)
@ -845,44 +564,61 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
return err;
}
if (P != R) {
err = mp_copy(P->x, R->x);
if (err == MP_OKAY)
err = mp_copy(P->y, R->y);
if (err == MP_OKAY)
err = mp_copy(P->z, R->z);
#ifdef ALT_ECC_SIZE
/* Use local stack variable */
x = ℞
y = &ry;
z = &rz;
if ((err = mp_init_multi(x, y, z, NULL, NULL, NULL)) != MP_OKAY) {
mp_clear(&t1);
mp_clear(&t2);
return err;
}
#else
/* Use destination directly */
x = R->x;
y = R->y;
z = R->z;
#endif
if (err == MP_OKAY)
err = mp_copy(P->x, x);
if (err == MP_OKAY)
err = mp_copy(P->y, y);
if (err == MP_OKAY)
err = mp_copy(P->z, z);
/* t1 = Z * Z */
if (err == MP_OKAY)
err = mp_sqr(R->z, &t1);
err = mp_sqr(z, &t1);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t1, modulus, *mp);
/* Z = Y * Z */
if (err == MP_OKAY)
err = mp_mul(R->z, R->y, R->z);
err = mp_mul(z, y, z);
if (err == MP_OKAY)
err = mp_montgomery_reduce(R->z, modulus, *mp);
err = mp_montgomery_reduce(z, modulus, *mp);
/* Z = 2Z */
if (err == MP_OKAY)
err = mp_add(R->z, R->z, R->z);
err = mp_add(z, z, z);
if (err == MP_OKAY) {
if (mp_cmp(R->z, modulus) != MP_LT)
err = mp_sub(R->z, modulus, R->z);
if (mp_cmp(z, modulus) != MP_LT)
err = mp_sub(z, modulus, z);
}
/* T2 = X - T1 */
if (err == MP_OKAY)
err = mp_sub(R->x, &t1, &t2);
err = mp_sub(x, &t1, &t2);
if (err == MP_OKAY) {
if (mp_cmp_d(&t2, 0) == MP_LT)
err = mp_add(&t2, modulus, &t2);
}
/* T1 = X + T1 */
if (err == MP_OKAY)
err = mp_add(&t1, R->x, &t1);
err = mp_add(&t1, x, &t1);
if (err == MP_OKAY) {
if (mp_cmp(&t1, modulus) != MP_LT)
err = mp_sub(&t1, modulus, &t1);
@ -909,20 +645,20 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
}
/* Y = 2Y */
if (err == MP_OKAY)
err = mp_add(R->y, R->y, R->y);
err = mp_add(y, y, y);
if (err == MP_OKAY) {
if (mp_cmp(R->y, modulus) != MP_LT)
err = mp_sub(R->y, modulus, R->y);
if (mp_cmp(y, modulus) != MP_LT)
err = mp_sub(y, modulus, y);
}
/* Y = Y * Y */
if (err == MP_OKAY)
err = mp_sqr(R->y, R->y);
err = mp_sqr(y, y);
if (err == MP_OKAY)
err = mp_montgomery_reduce(R->y, modulus, *mp);
err = mp_montgomery_reduce(y, modulus, *mp);
/* T2 = Y * Y */
if (err == MP_OKAY)
err = mp_sqr(R->y, &t2);
err = mp_sqr(y, &t2);
if (err == MP_OKAY)
err = mp_montgomery_reduce(&t2, modulus, *mp);
@ -936,59 +672,69 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
/* Y = Y * X */
if (err == MP_OKAY)
err = mp_mul(R->y, R->x, R->y);
err = mp_mul(y, x, y);
if (err == MP_OKAY)
err = mp_montgomery_reduce(R->y, modulus, *mp);
err = mp_montgomery_reduce(y, modulus, *mp);
/* X = T1 * T1 */
if (err == MP_OKAY)
err = mp_sqr(&t1, R->x);
err = mp_sqr(&t1, x);
if (err == MP_OKAY)
err = mp_montgomery_reduce(R->x, modulus, *mp);
err = mp_montgomery_reduce(x, modulus, *mp);
/* X = X - Y */
if (err == MP_OKAY)
err = mp_sub(R->x, R->y, R->x);
err = mp_sub(x, y, x);
if (err == MP_OKAY) {
if (mp_cmp_d(R->x, 0) == MP_LT)
err = mp_add(R->x, modulus, R->x);
if (mp_cmp_d(x, 0) == MP_LT)
err = mp_add(x, modulus, x);
}
/* X = X - Y */
if (err == MP_OKAY)
err = mp_sub(R->x, R->y, R->x);
err = mp_sub(x, y, x);
if (err == MP_OKAY) {
if (mp_cmp_d(R->x, 0) == MP_LT)
err = mp_add(R->x, modulus, R->x);
if (mp_cmp_d(x, 0) == MP_LT)
err = mp_add(x, modulus, x);
}
/* Y = Y - X */
if (err == MP_OKAY)
err = mp_sub(R->y, R->x, R->y);
err = mp_sub(y, x, y);
if (err == MP_OKAY) {
if (mp_cmp_d(R->y, 0) == MP_LT)
err = mp_add(R->y, modulus, R->y);
if (mp_cmp_d(y, 0) == MP_LT)
err = mp_add(y, modulus, y);
}
/* Y = Y * T1 */
if (err == MP_OKAY)
err = mp_mul(R->y, &t1, R->y);
err = mp_mul(y, &t1, y);
if (err == MP_OKAY)
err = mp_montgomery_reduce(R->y, modulus, *mp);
err = mp_montgomery_reduce(y, modulus, *mp);
/* Y = Y - T2 */
if (err == MP_OKAY)
err = mp_sub(R->y, &t2, R->y);
err = mp_sub(y, &t2, y);
if (err == MP_OKAY) {
if (mp_cmp_d(R->y, 0) == MP_LT)
err = mp_add(R->y, modulus, R->y);
if (mp_cmp_d(y, 0) == MP_LT)
err = mp_add(y, modulus, y);
}
#ifdef ALT_ECC_SIZE
if (err == MP_OKAY)
err = mp_copy(x, R->x);
if (err == MP_OKAY)
err = mp_copy(y, R->y);
if (err == MP_OKAY)
err = mp_copy(z, R->z);
#endif
#ifndef USE_FAST_MATH
/* clean up */
mp_clear(&t1);
mp_clear(&t2);
#endif
return err;
}
#endif /* USE_FAST_MATH */
/**
Map a projective jacbobian point back to affine space