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simplify ec_point slightly by using subx,negx

master
Michael Hamburg 10 years ago
parent
ebb6b4db6d
commit
a412e7b51f
1 changed files with 61 additions and 120 deletions
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  1. +61
    -120
      src/ec_point.c

+ 61
- 120
src/ec_point.c View File

@@ -53,27 +53,42 @@ field_mulw_scc_wr (
field_weak_reduce(out);
}

static __inline__ void
field_subx (
struct field_t *d,
const struct field_t *a,
const struct field_t *b
) {
field_sub ( d, a, b );
field_bias( d, 2 );
IF32( field_weak_reduce ( d ) );
}

static __inline__ void
field_negx (
struct field_t *d,
const struct field_t *a
) {
field_neg ( d, a );
field_bias( d, 2 );
IF32( field_weak_reduce ( d ) );
}

void
add_tw_niels_to_tw_extensible (
struct tw_extensible_t* d,
const struct tw_niels_t* e
) {
struct field_t L0, L1;
field_sub ( &L1, &d->y, &d->x );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &d->y, &d->x );
field_mul ( &L0, &e->a, &L1 );
field_add ( &L1, &d->x, &d->y );
field_mul ( &d->y, &e->b, &L1 );
field_mul ( &L1, &d->u, &d->t );
field_mul ( &d->x, &e->c, &L1 );
field_add ( &d->u, &L0, &d->y );
field_sub ( &d->t, &d->y, &L0 );
field_bias ( &d->t, 2 );
IF32( field_weak_reduce( &d->t ) );
field_sub ( &d->y, &d->z, &d->x );
field_bias ( &d->y, 2 );
IF32( field_weak_reduce( &d->y ) );
field_subx ( &d->t, &d->y, &L0 );
field_subx ( &d->y, &d->z, &d->x );
field_add ( &L0, &d->x, &d->z );
field_mul ( &d->z, &L0, &d->y );
field_mul ( &d->x, &d->y, &d->t );
@@ -86,22 +101,16 @@ sub_tw_niels_from_tw_extensible (
const struct tw_niels_t* e
) {
struct field_t L0, L1;
field_sub ( &L1, &d->y, &d->x );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &d->y, &d->x );
field_mul ( &L0, &e->b, &L1 );
field_add ( &L1, &d->x, &d->y );
field_mul ( &d->y, &e->a, &L1 );
field_mul ( &L1, &d->u, &d->t );
field_mul ( &d->x, &e->c, &L1 );
field_add ( &d->u, &L0, &d->y );
field_sub ( &d->t, &d->y, &L0 );
field_bias ( &d->t, 2 );
IF32( field_weak_reduce( &d->t ) );
field_subx ( &d->t, &d->y, &L0 );
field_add ( &d->y, &d->x, &d->z );
field_sub ( &L0, &d->z, &d->x );
field_bias ( &L0, 2 );
IF32( field_weak_reduce( &L0 ) );
field_subx ( &L0, &d->z, &d->x );
field_mul ( &d->z, &L0, &d->y );
field_mul ( &d->x, &d->y, &d->t );
field_mul ( &d->y, &L0, &d->u );
@@ -142,9 +151,7 @@ double_tw_extensible (
field_sub ( &a->t, &L1, &a->u );
field_bias ( &a->t, 3 );
IF32( field_weak_reduce( &a->t ) );
field_sub ( &L1, &L0, &L2 );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &L0, &L2 );
field_sqr ( &a->x, &a->z );
field_bias ( &a->x, 2-is32 /*is32 ? 1 : 2*/ );
field_add ( &a->z, &a->x, &a->x );
@@ -168,9 +175,7 @@ double_extensible (
field_sub ( &a->t, &a->u, &L1 );
field_bias ( &a->t, 3 );
IF32( field_weak_reduce( &a->t ) );
field_sub ( &a->u, &L0, &L2 );
field_bias ( &a->u, 2 );
IF32( field_weak_reduce( &a->u ) );
field_subx ( &a->u, &L0, &L2 );
field_sqr ( &a->x, &a->z );
field_bias ( &a->x, 2 );
field_add ( &a->z, &a->x, &a->x );
@@ -195,9 +200,7 @@ twist_and_double (
field_sub ( &b->t, &L0, &b->u );
field_bias ( &b->t, 3 );
IF32( field_weak_reduce( &b->t ) );
field_sub ( &L0, &b->z, &b->x );
field_bias ( &L0, 2 );
IF32( field_weak_reduce( &L0 ) );
field_subx ( &L0, &b->z, &b->x );
field_sqr ( &b->x, &a->z );
field_bias ( &b->x, 2 );
field_add ( &b->z, &b->x, &b->x );
@@ -222,9 +225,7 @@ untwist_and_double (
field_sub ( &b->t, &b->u, &L0 );
field_bias ( &b->t, 3 );
IF32( field_weak_reduce( &b->t ) );
field_sub ( &b->u, &b->z, &b->x );
field_bias ( &b->u, 2 );
IF32( field_weak_reduce( &b->u ) );
field_subx ( &b->u, &b->z, &b->x );
field_sqr ( &b->x, &a->z );
field_bias ( &b->x, 2-is32 /*is32 ? 1 : 2*/ );
field_add ( &b->z, &b->x, &b->x );
@@ -296,9 +297,7 @@ convert_tw_pniels_to_tw_extensible (
const struct tw_pniels_t* d
) {
field_add ( &e->u, &d->n.b, &d->n.a );
field_sub ( &e->t, &d->n.b, &d->n.a );
field_bias ( &e->t, 2 );
IF32( field_weak_reduce( &e->t ) );
field_subx ( &e->t, &d->n.b, &d->n.a );
field_mul ( &e->x, &d->z, &e->t );
field_mul ( &e->y, &d->z, &e->u );
field_sqr ( &e->z, &d->z );
@@ -325,28 +324,20 @@ montgomery_step (
) {
struct field_t L0, L1;
field_add ( &L0, &a->zd, &a->xd );
field_sub ( &L1, &a->xd, &a->zd );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_sub ( &a->zd, &a->xa, &a->za );
field_bias ( &a->zd, 2 );
IF32( field_weak_reduce( &a->zd ) );
field_subx ( &L1, &a->xd, &a->zd );
field_subx ( &a->zd, &a->xa, &a->za );
field_mul ( &a->xd, &L0, &a->zd );
field_add ( &a->zd, &a->za, &a->xa );
field_mul ( &a->za, &L1, &a->zd );
field_add ( &a->xa, &a->za, &a->xd );
field_sqr ( &a->zd, &a->xa );
field_mul ( &a->xa, &a->z0, &a->zd );
field_sub ( &a->zd, &a->xd, &a->za );
field_bias ( &a->zd, 2 );
IF32( field_weak_reduce( &a->zd ) );
field_subx ( &a->zd, &a->xd, &a->za );
field_sqr ( &a->za, &a->zd );
field_sqr ( &a->xd, &L0 );
field_sqr ( &L0, &L1 );
field_mulw_scc ( &a->zd, &a->xd, 1-EDWARDS_D ); /* FIXME PERF MULW */
field_sub ( &L1, &a->xd, &L0 );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &a->xd, &L0 );
field_mul ( &a->xd, &L0, &a->zd );
field_sub ( &L0, &a->zd, &L1 );
field_bias ( &L0, 4 - 2*is32 /*is32 ? 2 : 4*/ );
@@ -375,19 +366,13 @@ serialize_montgomery (
mask_t L4, L5, L6;
struct field_t L0, L1, L2, L3;
field_mul ( &L3, &a->z0, &a->zd );
field_sub ( &L1, &L3, &a->xd );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &L3, &a->xd );
field_mul ( &L3, &a->za, &L1 );
field_mul ( &L2, &a->z0, &a->xd );
field_sub ( &L1, &L2, &a->zd );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &L2, &a->zd );
field_mul ( &L0, &a->xa, &L1 );
field_add ( &L2, &L0, &L3 );
field_sub ( &L1, &L3, &L0 );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_subx ( &L1, &L3, &L0 );
field_mul ( &L3, &L1, &L2 );
field_copy ( &L2, &a->z0 );
field_addw ( &L2, 1 );
@@ -427,9 +412,7 @@ serialize_extensible (
const struct extensible_t* a
) {
struct field_t L0, L1, L2;
field_sub ( &L0, &a->y, &a->z );
field_bias ( &L0, 2 );
IF32( field_weak_reduce( &L0 ) );
field_subx ( &L0, &a->y, &a->z );
field_add ( b, &a->z, &a->y );
field_mul ( &L1, &a->z, &a->x );
field_mul ( &L2, &L0, &L1 );
@@ -461,22 +444,16 @@ decaf_serialize_extensible (
field_mul ( &L3, &L2, &a->t ); // L3 = d*y*t_
field_mul ( &L2, &L3, &a->u ); // L2 = d*y*t
field_mul ( &L0, &a->x, &a->z ); // L0 = x*z
field_sub ( &L3, &L2, &L0 );
field_bias ( &L3, 2 );
IF32( field_weak_reduce( &L3 ) ); // L3 = d*y*t - x*z
field_subx ( &L3, &L2, &L0 ); // L3 = d*y*t - x*z
field_add ( &L0, &a->y, &a->z ); // L0 = y+z
field_sub ( &L1, &a->y, &a->z );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) ); // L1 = y-z
field_subx ( &L1, &a->y, &a->z ); // L1 = y-z
field_mul ( &L2, &L1, &L0 ); // L2 = y^2-z^2
field_isr ( &L2, &L2 ); // L2 = 1/sqrt(y^2-z^2)
field_sqr ( &L1, &L2 ); // L1 = 1/(y^2-z^2)
field_mul ( &L0, &L1, &L3 ); // L0 = (d*y*t - z*x)/(y^2-z^2) = 1/x
field_mul ( &L1, &L2, &sqrt_d_minus_1 ); // L1 = sy
field_add ( &L3, &L1, &L1 ); // L3 = 2*sy
field_neg ( &L3, &L3 );
field_bias ( &L3, 2 );
IF32( field_weak_reduce( &L3 ) ); // L3 = -2*sy
field_negx ( &L3, &L3 ); // L3 = -2*sy
field_mul ( &L2, &L3, &a->z ); // L2 = -2*sy*z
field_cond_neg ( &L1, field_low_bit(&L2) ); // cond-neg sy
field_mul ( &L2, &L1, &a->y ); // L2 = 2*sy*y
@@ -495,22 +472,16 @@ decaf_serialize_tw_extensible (
field_mul ( &L3, &L2, &a->t ); // L3 = (1-d)*y*t_
field_mul ( &L2, &L3, &a->u ); // L2 = (1-d)*y*t
field_mul ( &L0, &a->x, &a->z ); // L0 = x*z
field_sub ( &L3, &L2, &L0 );
field_bias ( &L3, 2 );
IF32( field_weak_reduce( &L3 ) ); // L3 = d*y*t - x*z
field_subx ( &L3, &L2, &L0 ); // L3 = d*y*t - x*z
field_add ( &L0, &a->z, &a->y ); // L0 = y+z
field_sub ( &L1, &a->z, &a->y );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) ); // L1 = z-y
field_subx ( &L1, &a->z, &a->y ); // L1 = z-y
field_mul ( &L2, &L1, &L0 ); // L2 = z^2-y^2
field_isr ( &L2, &L2 ); // L2 = 1/sqrt(z^2-y^2)
field_sqr ( &L1, &L2 ); // L1 = 1/(z^2-y^2)
field_mul ( &L0, &L1, &L3 ); // L0 = ((1-d)*y*t - z*x)/(y^2-z^2) = 1/x
field_mul ( &L1, &L2, &sqrt_minus_d ); // L1 = sy
field_add ( &L3, &L1, &L1 ); // L3 = 2*sy
field_neg ( &L3, &L3 );
field_bias ( &L3, 2 );
IF32( field_weak_reduce( &L3 ) ); // L3 = -2*sy
field_negx ( &L3, &L3 ); // L3 = -2*sy
field_mul ( &L2, &L3, &a->z ); // L2 = -2*sy*z
field_cond_neg ( &L1, field_low_bit(&L2) ); // cond-neg sy
field_mul ( &L2, &L1, &a->y ); // L2 = 2*sy*y
@@ -552,10 +523,8 @@ decaf_deserialize_affine (
field_add ( &L0, &L0, &L0 );
field_mul ( &a->x, &L0, s );
field_mul ( &L2, &L1, &L3 );
field_neg ( &L1, &L1 );
field_bias ( &L1, 2 );
field_negx ( &L1, &L1 );
field_addw ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_mul ( &a->y, &L1, &L2 );
field_addw ( &a->y, -zero );
return succ;
@@ -573,10 +542,8 @@ decaf_deserialize_tw_affine (
succ = allow_identity | ~zero;
succ &= ~field_low_bit(s);
field_sqr ( &L0, s );
field_neg ( &L1, &L0 );
field_bias ( &L1, 2 );
field_negx ( &L1, &L0 );
field_addw ( &L1, 1 );
IF32( field_weak_reduce( &L1 ) );
field_make_nonzero ( &L1 );
field_sqr ( &L2, &L1 );
field_mulw_scc_wr ( &L3, &L0, 4-4*EDWARDS_D );
@@ -597,10 +564,8 @@ decaf_deserialize_tw_affine (
field_add ( &L0, &L0, &L0 );
field_mul ( &a->x, &L0, s );
field_mul ( &L2, &L1, &L3 );
field_neg ( &L1, &L1 );
field_bias ( &L1, 2 );
field_negx ( &L1, &L1 );
field_addw ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_mul ( &a->y, &L1, &L2 );
field_addw ( &a->y, -zero );
return succ;
@@ -641,16 +606,10 @@ twist_even (
mask_t L0, L1;
field_sqr ( &b->y, &a->z );
field_sqr ( &b->z, &a->x );
field_sub ( &b->u, &b->y, &b->z );
field_bias ( &b->u, 2 );
IF32( field_weak_reduce( &b->u ) );
field_sub ( &b->z, &a->z, &a->x );
field_bias ( &b->z, 2 );
IF32( field_weak_reduce( &b->z ) );
field_subx ( &b->u, &b->y, &b->z );
field_subx ( &b->z, &a->z, &a->x );
field_mul ( &b->y, &b->z, &a->y );
field_sub ( &b->z, &a->z, &a->y );
field_bias ( &b->z, 2 );
IF32( field_weak_reduce( &b->z ) );
field_subx ( &b->z, &a->z, &a->y );
field_mul ( &b->x, &b->z, &b->y );
field_mul ( &b->t, &b->x, &b->u );
field_mul ( &b->y, &b->x, &b->t );
@@ -683,13 +642,9 @@ test_only_twist (
field_add ( &b->y, &b->z, &b->z );
field_add ( &b->u, &b->y, &b->y );
IF32( field_weak_reduce( &b->u ) );
field_sub ( &b->y, &a->z, &a->x );
field_bias ( &b->y, 2 );
IF32( field_weak_reduce( &b->y ) );
field_subx ( &b->y, &a->z, &a->x );
field_mul ( &b->x, &b->y, &a->y );
field_sub ( &b->z, &a->z, &a->y );
field_bias ( &b->z, 2 );
IF32( field_weak_reduce( &b->z ) );
field_subx ( &b->z, &a->z, &a->y );
field_mul ( &b->t, &b->z, &b->x );
field_mul ( &L1, &b->t, &b->u );
field_mul ( &b->x, &b->t, &L1 );
@@ -699,14 +654,10 @@ test_only_twist (
field_mul ( &b->t, &b->x, &L1 );
field_add ( &L1, &a->y, &a->x );
IF32( field_weak_reduce( &L1 ) );
field_sub ( &L0, &a->x, &a->y );
field_bias ( &L0, 2 );
IF32( field_weak_reduce( &L0 ) );
field_subx ( &L0, &a->x, &a->y );
field_mul ( &b->x, &b->t, &L0 );
field_add ( &L0, &b->x, &L1 );
field_sub ( &b->t, &L1, &b->x );
field_bias ( &b->t, 2 );
IF32( field_weak_reduce( &b->t ) );
field_subx ( &b->t, &L1, &b->x );
field_mul ( &b->x, &L0, &b->u );
L2 = field_is_zero( &b->y );
L3 = - L2;
@@ -731,9 +682,7 @@ is_even_pt (
struct field_t L0, L1, L2;
field_sqr ( &L2, &a->z );
field_sqr ( &L1, &a->x );
field_sub ( &L0, &L2, &L1 );
field_bias ( &L0, 2 );
field_weak_reduce( &L0 );
field_subx ( &L0, &L2, &L1 );
return field_is_square ( &L0 );
}

@@ -766,9 +715,7 @@ deserialize_affine (
IF32( field_weak_reduce( &L3 ) );
field_copy ( &a->y, &L1 );
field_subw ( &a->y, 1 );
field_neg ( &a->x, &a->y );
field_bias ( &a->x, 2 );
IF32( field_weak_reduce( &a->x ) );
field_negx ( &a->x, &a->y );
field_mul ( &a->y, &a->x, &L3 );
field_sqr ( &L2, &a->x );
field_mul ( &L0, &L2, &a->y );
@@ -805,9 +752,7 @@ deserialize_and_twist_approx (
IF32( field_weak_reduce( &a->y ) );
field_sqr ( &a->x, &a->z );
field_subw ( &a->x, 1 );
field_neg ( &a->u, &a->x );
field_bias ( &a->u, 2 );
IF32( field_weak_reduce( &a->u ) );
field_negx ( &a->u, &a->x );
field_mul ( &a->x, sdm1, &a->u );
field_mul ( &L0, &a->x, &a->y );
field_mul ( &a->t, &L0, &a->y );
@@ -823,9 +768,7 @@ deserialize_and_twist_approx (
field_mul ( &L0, &a->u, &a->x );
field_copy ( &a->x, &a->z );
field_subw ( &a->x, 1 );
field_neg ( &L1, &a->x );
field_bias ( &L1, 2 );
IF32( field_weak_reduce( &L1 ) );
field_negx ( &L1, &a->x );
field_mul ( &a->x, &L1, &L0 );
field_mul ( &L0, &a->u, &a->y );
field_addw ( &a->z, 1 );
@@ -962,9 +905,7 @@ elligator_2s_inject (
field_sqr ( &L3, &a->x );
field_copy ( &a->y, &L3 );
field_subw ( &a->y, 1 );
field_neg ( &L4, &a->y );
field_bias ( &L4, 2 );
IF32( field_weak_reduce( &L4 ) );
field_negx ( &L4, &a->y );
field_sqr ( &L2, &L4 );
field_mulw ( &L7, &L2, (EDWARDS_D-1)*(EDWARDS_D-1) );
field_mulw ( &L8, &L3, 4*(EDWARDS_D+1)*(EDWARDS_D+1) );


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