Replaced add_generic with add_mixed
This commit is contained in:
Manuel Pégourié-Gonnard
Paul Bakker
parent
989c32bc3e
commit
7e0adfbcc5
174
library/ecp.c
174
library/ecp.c
@ -225,13 +225,43 @@ static void ecp_ptjac_init( ecp_ptjac *P )
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}
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/*
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* Free a point in Jacobian cooridnates
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* Free a point in Jacobian coordinates
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*/
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static void ecp_ptjac_free( ecp_ptjac *P )
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{
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mpi_free( &P->X ); mpi_free( &P->Y ); mpi_free( &P->Z );
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}
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/*
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* Copy P to R in Jacobian coordinates
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*/
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static int ecp_ptjac_copy( ecp_ptjac *R, const ecp_ptjac *P )
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{
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int ret = 0;
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MPI_CHK( mpi_copy( &R->X, &P->X ) );
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MPI_CHK( mpi_copy( &R->Y, &P->Y ) );
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MPI_CHK( mpi_copy( &R->Z, &P->Z ) );
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cleanup:
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return( ret );
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}
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/*
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* Set P to zero in Jacobian coordinates
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*/
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static int ecp_ptjac_set_zero( ecp_ptjac *P )
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{
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int ret = 0;
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MPI_CHK( mpi_lset( &P->X, 1 ) );
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MPI_CHK( mpi_lset( &P->Y, 1 ) );
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MPI_CHK( mpi_lset( &P->Z, 0 ) );
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cleanup:
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return( ret );
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}
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/*
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* Convert from affine to Jacobian coordinates
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*/
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@ -240,17 +270,11 @@ static int ecp_aff_to_jac( ecp_ptjac *jac, const ecp_point *aff )
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int ret = 0;
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if( aff->is_zero )
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{
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MPI_CHK( mpi_lset( &jac->X, 1 ) );
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MPI_CHK( mpi_lset( &jac->Y, 1 ) );
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MPI_CHK( mpi_lset( &jac->Z, 0 ) );
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}
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else
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{
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MPI_CHK( mpi_copy( &jac->X, &aff->X ) );
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MPI_CHK( mpi_copy( &jac->Y, &aff->Y ) );
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MPI_CHK( mpi_lset( &jac->Z, 1 ) );
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}
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return( ecp_ptjac_set_zero( jac ) );
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MPI_CHK( mpi_copy( &jac->X, &aff->X ) );
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MPI_CHK( mpi_copy( &jac->Y, &aff->Y ) );
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MPI_CHK( mpi_lset( &jac->Z, 1 ) );
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cleanup:
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return( ret );
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@ -305,17 +329,12 @@ static int ecp_double_jac( const ecp_group *grp, ecp_ptjac *R,
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int ret = 0;
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mpi T1, T2, T3, X, Y, Z;
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if( mpi_cmp_int( &P->Z, 0 ) == 0 )
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return( ecp_ptjac_set_zero( R ) );
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mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 );
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mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z );
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if( mpi_cmp_int( &P->Z, 0 ) == 0 )
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{
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MPI_CHK( mpi_lset( &R->X, 1 ) );
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MPI_CHK( mpi_lset( &R->Y, 1 ) );
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MPI_CHK( mpi_lset( &R->Z, 0 ) );
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goto cleanup;
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}
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MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) );
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MPI_CHK( mpi_sub_mpi( &T2, &P->X, &T1 ) );
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MPI_CHK( mpi_add_mpi( &T1, &P->X, &T1 ) );
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@ -349,63 +368,74 @@ cleanup:
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}
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/*
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* Addition: R = P + Q, generic case (P != Q, P != 0, Q != 0, R != 0)
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* Cf SEC1 v2 p. 7, item 4
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* Addition: R = P + Q, mixed affine-Jacobian coordinates (GECC 3.22)
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*/
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static int ecp_add_generic( const ecp_group *grp, ecp_point *R,
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const ecp_point *P, const ecp_point *Q )
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static int ecp_add_mixed( const ecp_group *grp, ecp_ptjac *R,
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const ecp_ptjac *P, const ecp_point *Q )
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{
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int ret = 0;
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mpi DX, DY, K, L, LL, X, Y;
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mpi_init( &DX ); mpi_init( &DY ); mpi_init( &K ); mpi_init( &L );
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mpi_init( &LL ); mpi_init( &X ); mpi_init( &Y );
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mpi T1, T2, T3, T4, X, Y, Z;
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/*
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* L = (Q.Y - P.Y) / (Q.X - P.X) mod p
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* Trivial cases: P == 0 or Q == 0
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*/
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MPI_CHK( mpi_sub_mpi( &DY, &Q->Y, &P->Y ) );
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MPI_CHK( mpi_sub_mpi( &DX, &Q->X, &P->X ) );
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MPI_CHK( mpi_inv_mod( &K, &DX, &grp->P ) );
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MPI_CHK( mpi_mul_mpi( &K, &K, &DY ) );
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MPI_CHK( mpi_mod_mpi( &L, &K, &grp->P ) );
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if( mpi_cmp_int( &P->Z, 0 ) == 0 )
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return( ecp_aff_to_jac( R, Q ) );
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/*
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* LL = L^2 mod p
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*/
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MPI_CHK( mpi_mul_mpi( &LL, &L, &L ) );
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MPI_CHK( mpi_mod_mpi( &LL, &LL, &grp->P ) );
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if( Q->is_zero )
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return( ecp_ptjac_copy( R, P ) );
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/*
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* X = L^2 - P.X - Q.X
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*/
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MPI_CHK( mpi_sub_mpi( &X, &LL, &P->X ) );
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MPI_CHK( mpi_sub_mpi( &X, &X, &Q->X ) );
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mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 ); mpi_init( &T4 );
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mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z );
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/*
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* Y = L * (P.X - X) - P.Y
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*/
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MPI_CHK( mpi_sub_mpi( &Y, &P->X, &X) );
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MPI_CHK( mpi_mul_mpi( &Y, &Y, &L ) );
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MPI_CHK( mpi_sub_mpi( &Y, &Y, &P->Y ) );
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MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) );
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MPI_CHK( mpi_mul_mpi( &T2, &T1, &P->Z ) );
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MPI_CHK( mpi_mul_mpi( &T1, &T1, &Q->X ) );
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MPI_CHK( mpi_mul_mpi( &T2, &T2, &Q->Y ) );
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MPI_CHK( mpi_sub_mpi( &T1, &T1, &P->X ) );
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MPI_CHK( mpi_sub_mpi( &T2, &T2, &P->Y ) );
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if( mpi_cmp_int( &T1, 0 ) == 0 )
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{
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if( mpi_cmp_int( &T2, 0 ) == 0 )
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{
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ret = ecp_double_jac( grp, R, P );
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goto cleanup;
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}
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else
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{
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ret = ecp_ptjac_set_zero( R );
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goto cleanup;
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}
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}
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MPI_CHK( mpi_mul_mpi( &Z, &P->Z, &T1 ) );
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MPI_CHK( mpi_mul_mpi( &T3, &T1, &T1 ) );
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MPI_CHK( mpi_mul_mpi( &T4, &T3, &T1 ) );
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MPI_CHK( mpi_mul_mpi( &T3, &T3, &P->X ) );
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MPI_CHK( mpi_mul_int( &T1, &T3, 2 ) );
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MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) );
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MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) );
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MPI_CHK( mpi_sub_mpi( &X, &X, &T4 ) );
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MPI_CHK( mpi_sub_mpi( &T3, &T3, &X ) );
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MPI_CHK( mpi_mul_mpi( &T3, &T3, &T2 ) );
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MPI_CHK( mpi_mul_mpi( &T4, &T4, &P->Y ) );
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MPI_CHK( mpi_sub_mpi( &Y, &T3, &T4 ) );
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/*
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* R = (X mod p, Y mod p)
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*/
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R->is_zero = 0;
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MPI_CHK( mpi_mod_mpi( &R->X, &X, &grp->P ) );
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MPI_CHK( mpi_mod_mpi( &R->Y, &Y, &grp->P ) );
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MPI_CHK( mpi_mod_mpi( &R->Z, &Z, &grp->P ) );
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cleanup:
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mpi_free( &DX ); mpi_free( &DY ); mpi_free( &K ); mpi_free( &L );
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mpi_free( &LL ); mpi_free( &X ); mpi_free( &Y );
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mpi_free( &T1 ); mpi_free( &T2 ); mpi_free( &T3 ); mpi_free( &T4 );
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mpi_free( &X ); mpi_free( &Y ); mpi_free( &Z );
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return( ret );
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}
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/*
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* Addition: R = P + Q, cf p. 7 of SEC1 v2
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* Addition: R = P + Q, affine wrapper
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*/
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int ecp_add( const ecp_group *grp, ecp_point *R,
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const ecp_point *P, const ecp_point *Q )
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@ -415,37 +445,15 @@ int ecp_add( const ecp_group *grp, ecp_point *R,
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ecp_ptjac_init( &J );
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if( P->is_zero )
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{
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ret = ecp_copy( R, Q );
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}
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else if( Q->is_zero )
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{
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ret = ecp_copy( R, P );
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}
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else if( mpi_cmp_mpi( &P->X, &Q->X ) != 0 )
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{
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ret = ecp_add_generic( grp, R, P, Q );
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}
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else if( mpi_cmp_mpi( &P->Y, &Q->Y ) != 0 )
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{
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ecp_set_zero( R );
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}
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else
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{
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/*
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* P == Q
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*/
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ecp_aff_to_jac( &J, P );
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MPI_CHK( ecp_double_jac( grp, &J, &J ) );
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MPI_CHK( ecp_jac_to_aff( grp, R, &J ) );
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}
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MPI_CHK( ecp_aff_to_jac( &J, P ) );
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MPI_CHK( ecp_add_mixed( grp, &J, &J, Q ) );
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MPI_CHK( ecp_jac_to_aff( grp, R, &J ) );
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cleanup:
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ecp_ptjac_free( &J );
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return ret;
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return( ret );
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}
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/*
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