mbedtls/library/bignum_new.c
Gabor Mezei f049dbfe94 Add the new modulus and the residue structures
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
2022-08-05 17:03:56 +01:00

138 lines
3.1 KiB
C

/**
* Internal 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 "mbedtls/error.h"
#include "mbedtls/bignum.h"
#include "bignum_mod.h"
#define ciL (sizeof(mbedtls_mpi_uint)) /* chars in limb */
#define biL (ciL << 3) /* bits in limb */
#define biH (ciL << 2) /* half limb size */
/*
* Convert between bits/chars and number of limbs
* Divide first in order to avoid potential overflows
*/
#define BITS_TO_LIMBS(i) ( (i) / biL + ( (i) % biL != 0 ) )
#define CHARS_TO_LIMBS(i) ( (i) / ciL + ( (i) % ciL != 0 ) )
/*
* Count leading zero bits in a given integer
*/
static size_t mpi_clz( const mbedtls_mpi_uint x )
{
size_t j;
mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);
for( j = 0; j < biL; j++ )
{
if( x & mask ) break;
mask >>= 1;
}
return j;
}
/*
* Return the number of bits
*/
static size_t mpi_bitlen( const mbedtls_mpi_uint *X, size_t nx )
{
size_t i, j;
if( nx == 0 )
return( 0 );
for( i = nx - 1; i > 0; i-- )
if( X[i] != 0 )
break;
j = biL - mpi_clz( X[i] );
return( ( i * biL ) + j );
}
void mbedtls_mpi_mod_residue_release( mbedtls_mpi_mod_residue *r )
{
if ( r == NULL )
return;
r->n = 0;
r->p = NULL;
}
int mbedtls_mpi_mod_residue_setup( mbedtls_mpi_mod_residue *r,
mbedtls_mpi_mod_modulus *m,
mbedtls_mpi_uint *X )
{
if( X == NULL || m == NULL || r == NULL || X >= m->p)
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
r->n = m->n;
r->p = X;
return( 0 );
}
void mbedtls_mpi_mod_modulus_init( mbedtls_mpi_mod_modulus *m )
{
if ( m == NULL )
return;
m->rep.mont = 0;
}
void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m )
{
if ( m == NULL )
return;
m->p = NULL;
m->n = 0;
m->plen = 0;
m->ext_rep = 0;
m->int_rep = 0;
m->rep.mont = NULL;
m->rep.ored = NULL;
}
int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
mbedtls_mpi_uint *X,
size_t nx,
int ext_rep,
int int_rep )
{
if ( X == NULL || m == NULL )
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
m->p = X;
m->n = nx;
m->ext_rep = ext_rep;
m->int_rep = int_rep;
m->plen = mpi_bitlen( X, nx );
return( 0 );
}
#endif /* MBEDTLS_BIGNUM_C */