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Introduce muladd_restartable() and its sub-context

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Only the administrative parts for now, not actually restartable so far.
This commit is contained in:
Manuel Pégourié-Gonnard
2017-04-20 13:36:18 +02:00
parent a08cd1a77f
commit 54dd6527f0
4 changed files with 199 additions and 13 deletions
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94
library/ecp.c
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@ -101,9 +101,10 @@ void mbedtls_ecp_set_max_ops( unsigned max_ops )
}
/*
* Restart context type for interrupted operations
* Restart sub-context for ecp_mul_comb()
*/
struct mbedtls_ecp_restart_mul {
struct mbedtls_ecp_restart_mul
{
mbedtls_ecp_point R; /* current intermediate result */
size_t i; /* current index in various loops, 0 outside */
mbedtls_ecp_point *T; /* table for precomputed points */
@ -119,7 +120,7 @@ struct mbedtls_ecp_restart_mul {
};
/*
* Init restart_mul context
* Init restart_mul sub-context
*/
static void ecp_restart_mul_init( mbedtls_ecp_restart_mul_ctx *ctx )
{
@ -127,7 +128,7 @@ static void ecp_restart_mul_init( mbedtls_ecp_restart_mul_ctx *ctx )
}
/*
* Free the components of a restart_mul context
* Free the components of a restart_mul sub-context
*/
static void ecp_restart_mul_free( mbedtls_ecp_restart_mul_ctx *ctx )
{
@ -147,6 +148,33 @@ static void ecp_restart_mul_free( mbedtls_ecp_restart_mul_ctx *ctx )
memset( ctx, 0, sizeof( mbedtls_ecp_restart_mul_ctx ) );
}
/*
* Restart context for ecp_muladd()
*/
struct mbedtls_ecp_restart_muladd
{
int state; /* dummy for now */
};
/*
* Init restart_muladd sub-context
*/
static void ecp_restart_muladd_init( mbedtls_ecp_restart_muladd_ctx *ctx )
{
memset( ctx, 0, sizeof( *ctx ) );
}
/*
* Free the components of a restart_muladd sub-context
*/
static void ecp_restart_muladd_free( mbedtls_ecp_restart_muladd_ctx *ctx )
{
if( ctx == NULL )
return;
memset( ctx, 0, sizeof( *ctx ) );
}
/*
* Initialize a restart context
*/
@ -1868,9 +1896,9 @@ cleanup:
if( ret != 0 )
mbedtls_ecp_point_free( R );
/* clear restart context when not in progress (done or error) */
/* clear our sub-context when not in progress (done or error) */
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( rs_ctx != NULL && rs_ctx->rsm != NULL && ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) {
if( rs_ctx != NULL && ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) {
ecp_restart_mul_free( rs_ctx->rsm );
mbedtls_free( rs_ctx->rsm );
rs_ctx->rsm = NULL;
@ -2248,12 +2276,17 @@ cleanup:
}
/*
* Linear combination
* Restartable linear combination
* NOT constant-time
*/
int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
#if !defined(MBEDTLS_ECP_EARLY_RETURN)
static
#endif
int mbedtls_ecp_muladd_restartable(
mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_mpi *m, const mbedtls_ecp_point *P,
const mbedtls_mpi *n, const mbedtls_ecp_point *Q )
const mbedtls_mpi *n, const mbedtls_ecp_point *Q,
mbedtls_ecp_restart_ctx *rs_ctx )
{
int ret;
mbedtls_ecp_point mP;
@ -2261,9 +2294,29 @@ int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
char is_grp_capable = 0;
#endif
#if !defined(MBEDTLS_ECP_EARLY_RETURN)
(void) rs_ctx;
#endif
if( ecp_get_type( grp ) != ECP_TYPE_SHORT_WEIERSTRASS )
return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
/* reset ops count for this call if top-level */
if( rs_ctx != NULL && rs_ctx->depth++ == 0 )
rs_ctx->ops_done = 0;
/* set up our own sub-context if needed */
if( ecp_max_ops != 0 && rs_ctx != NULL && rs_ctx->ma == NULL )
{
rs_ctx->ma = mbedtls_calloc( 1, sizeof( mbedtls_ecp_restart_muladd_ctx ) );
if( rs_ctx->ma == NULL )
return( MBEDTLS_ERR_ECP_ALLOC_FAILED );
ecp_restart_muladd_init( rs_ctx->ma );
}
#endif /* MBEDTLS_ECP_EARLY_RETURN */
mbedtls_ecp_point_init( &mP );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul_shortcuts( grp, &mP, m, P ) );
@ -2290,9 +2343,32 @@ cleanup:
#endif /* MBEDTLS_ECP_INTERNAL_ALT */
mbedtls_ecp_point_free( &mP );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
/* clear our sub-context when not in progress (done or error) */
if( rs_ctx != NULL && ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) {
ecp_restart_muladd_free( rs_ctx->ma );
mbedtls_free( rs_ctx->ma );
rs_ctx->ma = NULL;
}
if( rs_ctx != NULL )
rs_ctx->depth--;
#endif /* MBEDTLS_ECP_EARLY_RETURN */
return( ret );
}
/*
* Linear combination
* NOT constant-time
*/
int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_mpi *m, const mbedtls_ecp_point *P,
const mbedtls_mpi *n, const mbedtls_ecp_point *Q )
{
return( mbedtls_ecp_muladd_restartable( grp, R, m, P, n, Q, NULL ) );
}
#if defined(ECP_MONTGOMERY)
/*