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Keep temporaries across iterations of ecp_add_mixed()

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This saves heap operations

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2022-01-04 07:34:14 +00:00
parent a7f8edd709
commit 3b29f2194b
1 changed files with 17 additions and 15 deletions
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32
library/ecp.c
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@ -1499,7 +1499,8 @@ cleanup:
* Cost: 1A := 8M + 3S
*/
static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q )
const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q,
mbedtls_mpi tmp[4] )
{
#if defined(MBEDTLS_SELF_TEST)
add_count++;
@ -1514,7 +1515,6 @@ static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
#else
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi tmp[4];
/* NOTE: Aliasing between input and output is allowed, so one has to make
* sure that at the point X,Y,Z are written, {P,Q}->{X,Y,Z} are no
@ -1538,11 +1538,6 @@ static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
if( Q->Z.p != NULL && mbedtls_mpi_cmp_int( &Q->Z, 1 ) != 0 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
mbedtls_mpi_init( &tmp[0] );
mbedtls_mpi_init( &tmp[1] );
mbedtls_mpi_init( &tmp[2] );
mbedtls_mpi_init( &tmp[3] );
MPI_ECP_SQR( &tmp[0], &P->Z );
MPI_ECP_MUL( &tmp[1], &tmp[0], &P->Z );
MPI_ECP_MUL( &tmp[0], &tmp[0], &Q->X );
@ -1586,11 +1581,6 @@ static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
cleanup:
mbedtls_mpi_free( &tmp[0] );
mbedtls_mpi_free( &tmp[1] );
mbedtls_mpi_free( &tmp[2] );
mbedtls_mpi_free( &tmp[3] );
return( ret );
#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT) */
}
@ -1872,7 +1862,7 @@ add:
{
j = i;
while( j-- )
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, &T[i + j], &T[j], &T[i] ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, &T[i + j], &T[j], &T[i], tmp ) );
}
#if defined(MBEDTLS_ECP_RESTARTABLE)
@ -2001,7 +1991,7 @@ static int ecp_mul_comb_core( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R
MBEDTLS_MPI_CHK( ecp_double_jac( grp, R, R, tmp ) );
MBEDTLS_MPI_CHK( ecp_select_comb( grp, &Txi, T, T_size, x[i] ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, R, R, &Txi ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, R, R, &Txi, tmp ) );
}
cleanup:
@ -2735,6 +2725,7 @@ int mbedtls_ecp_muladd_restartable(
mbedtls_ecp_point mP;
mbedtls_ecp_point *pmP = &mP;
mbedtls_ecp_point *pR = R;
mbedtls_mpi tmp[4];
#if defined(MBEDTLS_ECP_INTERNAL_ALT)
char is_grp_capable = 0;
#endif
@ -2750,6 +2741,11 @@ int mbedtls_ecp_muladd_restartable(
mbedtls_ecp_point_init( &mP );
mbedtls_mpi_init( &tmp[0] );
mbedtls_mpi_init( &tmp[1] );
mbedtls_mpi_init( &tmp[2] );
mbedtls_mpi_init( &tmp[3] );
ECP_RS_ENTER( ma );
#if defined(MBEDTLS_ECP_RESTARTABLE)
@ -2790,7 +2786,7 @@ mul2:
add:
#endif
MBEDTLS_ECP_BUDGET( MBEDTLS_ECP_OPS_ADD );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, pR, pmP, pR ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, pR, pmP, pR, tmp ) );
#if defined(MBEDTLS_ECP_RESTARTABLE)
if( rs_ctx != NULL && rs_ctx->ma != NULL )
rs_ctx->ma->state = ecp_rsma_norm;
@ -2806,6 +2802,12 @@ norm:
#endif
cleanup:
mbedtls_mpi_free( &tmp[0] );
mbedtls_mpi_free( &tmp[1] );
mbedtls_mpi_free( &tmp[2] );
mbedtls_mpi_free( &tmp[3] );
#if defined(MBEDTLS_ECP_INTERNAL_ALT)
if( is_grp_capable )
mbedtls_internal_ecp_free( grp );