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Start actually splitting computation

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Temporary state is quite inefficient: pre-computed table is recomputed every
single time. This is WIP obviously.
This commit is contained in:
Manuel Pégourié-Gonnard 2017-03-14 13:13:13 +01:00
parent 8962ddbb23
commit 2fad7ae02a
1 changed files with 59 additions and 9 deletions
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70
library/ecp.c
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@ -104,10 +104,14 @@ void mbedtls_ecp_set_max_ops( unsigned max_ops )
* Restart context type for interrupted operations
*/
struct mbedtls_ecp_restart {
unsigned char fake_it; /* for tests: should we fake early return? */
unsigned ops_done; /* number of operations done this time */
mbedtls_mpi m; /* saved argument: scalar */
mbedtls_ecp_point P; /* saved argument: point */
mbedtls_ecp_point R; /* current intermediate result */
enum {
ecp_rs_init = 0,
ecp_rs_final_norm,
} state;
};
/*
@ -129,7 +133,37 @@ static void ecp_restart_free( mbedtls_ecp_restart_ctx *ctx )
mbedtls_mpi_free( &ctx->m );
mbedtls_ecp_point_free( &ctx->P );
mbedtls_ecp_point_free( &ctx->R );
memset( ctx, 0, sizeof( mbedtls_ecp_restart_ctx ) );
}
/*
* Operation counts
*/
#define ECP_OPS_DBL 8 /* see ecp_double_jac() */
#define ECP_OPS_ADD 11 /* see ecp_add_mixed() */
#define ECP_OPS_INV 120 /* empirical equivalent */
/*
* Check if we can do the next step
*/
static int ecp_check_budget( const mbedtls_ecp_group *grp, unsigned ops )
{
if( grp->rs != NULL )
{
/* avoid infinite loops: always allow first step */
if( grp->rs->ops_done != 0 && grp->rs->ops_done + ops > ecp_max_ops )
return( MBEDTLS_ERR_ECP_IN_PROGRESS );
grp->rs->ops_done += ops;
}
return( 0 );
}
#define ECP_BUDGET( ops ) MBEDTLS_MPI_CHK( ecp_check_budget( grp, ops ) );
#else
#define ECP_BUDGET( ops )
#endif /* MBEDTLS_ECP_EARLY_RETURN */
#if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) || \
@ -1465,12 +1499,26 @@ static int ecp_mul_comb_after_precomp( const mbedtls_ecp_group *grp,
RR = &grp->rs->R;
#endif
MBEDTLS_MPI_CHK( ecp_comb_recode_scalar( grp, m, k, d, w, &parity_trick ) );
MBEDTLS_MPI_CHK( ecp_mul_comb_core( grp, RR, T, pre_len, k, d, f_rng, p_rng ) );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs == NULL || grp->rs->state < ecp_rs_final_norm )
#endif
{
MBEDTLS_MPI_CHK( ecp_comb_recode_scalar( grp, m, k, d, w,
&parity_trick ) );
MBEDTLS_MPI_CHK( ecp_mul_comb_core( grp, RR, T, pre_len, k, d,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( ecp_safe_invert_jac( grp, RR, parity_trick ) );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs != NULL )
grp->rs->state++;
#endif
/* XXX: temporary: should have counted some ops */
ECP_BUDGET( 42 );
}
ECP_BUDGET( ECP_OPS_INV );
MBEDTLS_MPI_CHK( ecp_normalize_jac( grp, RR ) );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
@ -1555,12 +1603,10 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &grp->rs->m, m ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &grp->rs->P, P ) );
}
#endif
/* XXX: temporary */
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs && ++grp->rs->fake_it != 0 )
return( MBEDTLS_ERR_ECP_IN_PROGRESS );
/* new start for ops counts */
if( grp->rs != NULL )
grp->rs->ops_done = 0;
#endif
/* Is P the base point ? */
@ -1614,6 +1660,10 @@ cleanup:
mbedtls_free( T );
}
/* don't free R while in progress in case R == P */
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
#endif
if( ret != 0 )
mbedtls_ecp_point_free( R );