Don't special-case a = -3, not worth it
diff --git a/library/ecp.c b/library/ecp.c
index d980d4b..b7af16a 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -288,15 +288,20 @@
}
/*
- * Import an ECP group from ASCII strings, case A == -3 (A cleared)
+ * Import an ECP group from ASCII strings, case A == -3
*/
int ecp_group_read_string( ecp_group *grp, int radix,
const char *p, const char *b,
const char *gx, const char *gy, const char *n)
{
- int ret = ecp_group_read_string_gen( grp, radix, p, "00", b, gx, gy, n );
+ int ret;
- mpi_free( &grp->A );
+ MPI_CHK( ecp_group_read_string_gen( grp, radix, p, "00", b, gx, gy, n ) );
+ MPI_CHK( mpi_add_int( &grp->A, &grp->P, -3 ) );
+
+cleanup:
+ if( ret != 0 )
+ ecp_group_free( grp );
return( ret );
}
@@ -1055,72 +1060,23 @@
}
/*
- * Point doubling R = 2 P, Jacobian coordinates with a == -3 (GECC 3.21)
- */
-static int ecp_double_jac_am3( const ecp_group *grp, ecp_point *R,
- const ecp_point *P )
-{
- int ret;
- mpi T1, T2, T3, X, Y, Z;
-
- if( mpi_cmp_int( &P->Z, 0 ) == 0 )
- return( ecp_set_zero( R ) );
-
- mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 );
- mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z );
-
- MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_sub_mpi( &T2, &P->X, &T1 ) ); MOD_SUB( T2 );
- MPI_CHK( mpi_add_mpi( &T1, &P->X, &T1 ) ); MOD_ADD( T1 );
- MPI_CHK( mpi_mul_mpi( &T2, &T2, &T1 ) ); MOD_MUL( T2 );
- MPI_CHK( mpi_mul_int( &T2, &T2, 3 ) ); MOD_ADD( T2 );
- MPI_CHK( mpi_mul_int( &Y, &P->Y, 2 ) ); MOD_ADD( Y );
- MPI_CHK( mpi_mul_mpi( &Z, &Y, &P->Z ) ); MOD_MUL( Z );
- MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
- MPI_CHK( mpi_mul_mpi( &T3, &Y, &P->X ) ); MOD_MUL( T3 );
- MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
-
- /*
- * For Y = Y / 2 mod p, we must make sure that Y is even before
- * using right-shift. No need to reduce mod p afterwards.
- */
- if( mpi_get_bit( &Y, 0 ) == 1 )
- MPI_CHK( mpi_add_mpi( &Y, &Y, &grp->P ) );
- MPI_CHK( mpi_shift_r( &Y, 1 ) );
-
- MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) ); MOD_MUL( X );
- MPI_CHK( mpi_mul_int( &T1, &T3, 2 ) ); MOD_ADD( T1 );
- MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) ); MOD_SUB( X );
- MPI_CHK( mpi_sub_mpi( &T1, &T3, &X ) ); MOD_SUB( T1 );
- MPI_CHK( mpi_mul_mpi( &T1, &T1, &T2 ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_sub_mpi( &Y, &T1, &Y ) ); MOD_SUB( Y );
-
- MPI_CHK( mpi_copy( &R->X, &X ) );
- MPI_CHK( mpi_copy( &R->Y, &Y ) );
- MPI_CHK( mpi_copy( &R->Z, &Z ) );
-
-cleanup:
-
- mpi_free( &T1 ); mpi_free( &T2 ); mpi_free( &T3 );
- mpi_free( &X ); mpi_free( &Y ); mpi_free( &Z );
-
- return( ret );
-}
-
-/*
- * Point doubling R = 2 P, Jacobian coordinates with general A
+ * Point doubling R = 2 P, Jacobian coordinates
*
* http://www.hyperelliptic.org/EFD/g1p/auto-code/shortw/jacobian/doubling/dbl-2007-bl.op3
* with heavy variable renaming, some reordering and one minor modification
* (a = 2 * b, c = d - 2a replaced with c = d, c = c - b, c = c - b)
* in order to use a lot less intermediate variables (6 vs 25).
*/
-static int ecp_double_jac_gen( const ecp_group *grp, ecp_point *R,
- const ecp_point *P )
+static int ecp_double_jac( const ecp_group *grp, ecp_point *R,
+ const ecp_point *P )
{
int ret;
mpi T1, T2, T3, X3, Y3, Z3;
+#if defined(POLARSSL_SELF_TEST)
+ dbl_count++;
+#endif
+
mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 );
mpi_init( &X3 ); mpi_init( &Y3 ); mpi_init( &Z3 );
@@ -1161,22 +1117,6 @@
}
/*
- * Point doubling R = 2 P, dispatcher function
- */
-static int ecp_double_jac( const ecp_group *grp, ecp_point *R,
- const ecp_point *P )
-{
-#if defined(POLARSSL_SELF_TEST)
- dbl_count++;
-#endif
-
- if( grp->A.p != NULL )
- return( ecp_double_jac_gen( grp, R, P ) );
- else
- return( ecp_double_jac_am3( grp, R, P ) );
-}
-
-/*
* Addition or subtraction: R = P + Q or R = P + Q,
* mixed affine-Jacobian coordinates (GECC 3.22)
*
@@ -1669,18 +1609,10 @@
/*
* YY = Y^2
* RHS = X (X^2 + A) + B = X^3 + A X + B
- * with, as usual, A = -3 if A is ommited
*/
MPI_CHK( mpi_mul_mpi( &YY, &pt->Y, &pt->Y ) ); MOD_MUL( YY );
MPI_CHK( mpi_mul_mpi( &RHS, &pt->X, &pt->X ) ); MOD_MUL( RHS );
- if( grp->A.p == NULL )
- {
- MPI_CHK( mpi_add_int( &RHS, &RHS, -3 ) ); MOD_SUB( RHS );
- }
- else
- {
- MPI_CHK( mpi_add_mpi( &RHS, &RHS, &grp->A ) ); MOD_ADD( RHS );
- }
+ MPI_CHK( mpi_add_mpi( &RHS, &RHS, &grp->A ) ); MOD_ADD( RHS );
MPI_CHK( mpi_mul_mpi( &RHS, &RHS, &pt->X ) ); MOD_MUL( RHS );
MPI_CHK( mpi_add_mpi( &RHS, &RHS, &grp->B ) ); MOD_ADD( RHS );