mbedtls/library/bignum_mod.c
Gilles Peskine e655479528 Generalize representation handling in mbedtls_mpi_mod_read
Call mbedtls_mpi_mod_raw_canonical_to_modulus_rep instead of assuming that
anything that isn't MBEDTLS_MPI_MOD_REP_MONTGOMERY is canonical.

mbedtls_mpi_mod_write should get the same treatment, but I'm holding off
until https://github.com/Mbed-TLS/mbedtls/issues/6679 is done.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2022-12-20 19:55:51 +01:00

309 lines
8 KiB
C

/**
* Modular bignum functions
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "common.h"
#if defined(MBEDTLS_BIGNUM_C)
#include <string.h>
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "mbedtls/bignum.h"
#include "mbedtls/platform.h"
#include "bignum_core.h"
#include "bignum_mod.h"
#include "bignum_mod_raw.h"
#include "constant_time_internal.h"
int mbedtls_mpi_mod_residue_setup( mbedtls_mpi_mod_residue *r,
const mbedtls_mpi_mod_modulus *m,
mbedtls_mpi_uint *p,
size_t p_limbs )
{
if( p_limbs != m->limbs || !mbedtls_mpi_core_lt_ct( p, m->p, m->limbs ) )
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
r->limbs = m->limbs;
r->p = p;
return( 0 );
}
void mbedtls_mpi_mod_residue_release( mbedtls_mpi_mod_residue *r )
{
if( r == NULL )
return;
r->limbs = 0;
r->p = NULL;
}
void mbedtls_mpi_mod_modulus_init( mbedtls_mpi_mod_modulus *m )
{
if( m == NULL )
return;
m->p = NULL;
m->limbs = 0;
m->bits = 0;
m->int_rep = MBEDTLS_MPI_MOD_REP_INVALID;
}
void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m )
{
if( m == NULL )
return;
switch( m->int_rep )
{
case MBEDTLS_MPI_MOD_REP_MONTGOMERY:
if (m->rep.mont.rr != NULL)
{
mbedtls_platform_zeroize( (mbedtls_mpi_uint *) m->rep.mont.rr,
m->limbs );
mbedtls_free( (mbedtls_mpi_uint *)m->rep.mont.rr );
m->rep.mont.rr = NULL;
}
m->rep.mont.mm = 0;
break;
case MBEDTLS_MPI_MOD_REP_OPT_RED:
mbedtls_free( m->rep.ored );
break;
case MBEDTLS_MPI_MOD_REP_INVALID:
break;
}
m->p = NULL;
m->limbs = 0;
m->bits = 0;
m->int_rep = MBEDTLS_MPI_MOD_REP_INVALID;
}
static int set_mont_const_square( const mbedtls_mpi_uint **X,
const mbedtls_mpi_uint *A,
size_t limbs )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi N;
mbedtls_mpi RR;
*X = NULL;
mbedtls_mpi_init( &N );
mbedtls_mpi_init( &RR );
if( A == NULL || limbs == 0 || limbs >= ( MBEDTLS_MPI_MAX_LIMBS / 2 ) - 2 )
goto cleanup;
if( mbedtls_mpi_grow( &N, limbs ) )
goto cleanup;
memcpy( N.p, A, sizeof(mbedtls_mpi_uint) * limbs );
ret = mbedtls_mpi_core_get_mont_r2_unsafe(&RR, &N);
if( ret == 0 )
{
*X = RR.p;
RR.p = NULL;
}
cleanup:
mbedtls_mpi_free(&N);
mbedtls_mpi_free(&RR);
ret = ( ret != 0 ) ? MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED : 0;
return( ret );
}
int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
const mbedtls_mpi_uint *p,
size_t p_limbs,
mbedtls_mpi_mod_rep_selector int_rep )
{
int ret = 0;
m->p = p;
m->limbs = p_limbs;
m->bits = mbedtls_mpi_core_bitlen( p, p_limbs );
switch( int_rep )
{
case MBEDTLS_MPI_MOD_REP_MONTGOMERY:
m->int_rep = int_rep;
m->rep.mont.mm = mbedtls_mpi_core_montmul_init( m->p );
ret = set_mont_const_square( &m->rep.mont.rr, m->p, m->limbs );
break;
case MBEDTLS_MPI_MOD_REP_OPT_RED:
m->int_rep = int_rep;
m->rep.ored = NULL;
break;
default:
ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
goto exit;
}
exit:
if( ret != 0 )
{
mbedtls_mpi_mod_modulus_free( m );
}
return( ret );
}
/* BEGIN MERGE SLOT 1 */
/* END MERGE SLOT 1 */
/* BEGIN MERGE SLOT 2 */
/* END MERGE SLOT 2 */
/* BEGIN MERGE SLOT 3 */
int mbedtls_mpi_mod_sub( mbedtls_mpi_mod_residue *X,
const mbedtls_mpi_mod_residue *A,
const mbedtls_mpi_mod_residue *B,
const mbedtls_mpi_mod_modulus *N )
{
if( X->limbs != N->limbs || A->limbs != N->limbs || B->limbs != N->limbs )
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
mbedtls_mpi_mod_raw_sub( X->p, A->p, B->p, N );
return( 0 );
}
/* END MERGE SLOT 3 */
/* BEGIN MERGE SLOT 4 */
/* END MERGE SLOT 4 */
/* BEGIN MERGE SLOT 5 */
int mbedtls_mpi_mod_add( mbedtls_mpi_mod_residue *X,
const mbedtls_mpi_mod_residue *A,
const mbedtls_mpi_mod_residue *B,
const mbedtls_mpi_mod_modulus *N )
{
if( X->limbs != N->limbs || A->limbs != N->limbs || B->limbs != N->limbs )
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
mbedtls_mpi_mod_raw_add(X->p, A->p, B->p, N);
return( 0 );
}
/* END MERGE SLOT 5 */
/* BEGIN MERGE SLOT 6 */
int mbedtls_mpi_mod_random( mbedtls_mpi_mod_residue *X,
mbedtls_mpi_uint min,
const mbedtls_mpi_mod_modulus *N,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
if( X->limbs != N->limbs )
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
return( mbedtls_mpi_mod_raw_random( X->p, min, N, f_rng, p_rng ) );
}
/* END MERGE SLOT 6 */
/* BEGIN MERGE SLOT 7 */
int mbedtls_mpi_mod_read( mbedtls_mpi_mod_residue *r,
const mbedtls_mpi_mod_modulus *m,
const unsigned char *buf,
size_t buflen,
mbedtls_mpi_mod_ext_rep ext_rep )
{
int ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
/* Do our best to check if r and m have been set up */
if( r->limbs == 0 || m->limbs == 0 )
goto cleanup;
if( r->limbs != m->limbs )
goto cleanup;
ret = mbedtls_mpi_mod_raw_read( r->p, m, buf, buflen, ext_rep );
if( ret != 0 )
goto cleanup;
r->limbs = m->limbs;
ret = mbedtls_mpi_mod_raw_canonical_to_modulus_rep( r->p, m );
cleanup:
return ( ret );
}
int mbedtls_mpi_mod_write( const mbedtls_mpi_mod_residue *r,
const mbedtls_mpi_mod_modulus *m,
unsigned char *buf,
size_t buflen,
mbedtls_mpi_mod_ext_rep ext_rep )
{
int ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
/* Do our best to check if r and m have been set up */
if( r->limbs == 0 || m->limbs == 0 )
goto cleanup;
if( r->limbs != m->limbs )
goto cleanup;
if( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
{
ret = mbedtls_mpi_mod_raw_from_mont_rep( r->p, m );
if( ret != 0 )
goto cleanup;
}
ret = mbedtls_mpi_mod_raw_write( r->p, m, buf, buflen, ext_rep );
if( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
{
/* If this fails, the value of r is corrupted and we want to return
* this error (as opposed to the error code from the write above) to
* let the caller know. If it succeeds, we want to return the error
* code from write above. */
int conv_ret = mbedtls_mpi_mod_raw_to_mont_rep( r->p, m );
if( ret == 0 )
ret = conv_ret;
}
cleanup:
return ( ret );
}
/* END MERGE SLOT 7 */
/* BEGIN MERGE SLOT 8 */
/* END MERGE SLOT 8 */
/* BEGIN MERGE SLOT 9 */
/* END MERGE SLOT 9 */
/* BEGIN MERGE SLOT 10 */
/* END MERGE SLOT 10 */
#endif /* MBEDTLS_BIGNUM_C */