138 lines
3.1 KiB
C
138 lines
3.1 KiB
C
/**
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* Internal bignum functions
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_BIGNUM_C)
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#include "mbedtls/error.h"
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#include "mbedtls/bignum.h"
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#include "bignum_mod.h"
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#define ciL (sizeof(mbedtls_mpi_uint)) /* chars in limb */
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#define biL (ciL << 3) /* bits in limb */
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#define biH (ciL << 2) /* half limb size */
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/*
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* Convert between bits/chars and number of limbs
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* Divide first in order to avoid potential overflows
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*/
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#define BITS_TO_LIMBS(i) ( (i) / biL + ( (i) % biL != 0 ) )
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#define CHARS_TO_LIMBS(i) ( (i) / ciL + ( (i) % ciL != 0 ) )
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/*
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* Count leading zero bits in a given integer
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*/
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static size_t mpi_clz( const mbedtls_mpi_uint x )
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{
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size_t j;
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mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);
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for( j = 0; j < biL; j++ )
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{
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if( x & mask ) break;
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mask >>= 1;
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}
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return j;
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}
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/*
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* Return the number of bits
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*/
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static size_t mpi_bitlen( const mbedtls_mpi_uint *X, size_t nx )
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{
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size_t i, j;
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if( nx == 0 )
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return( 0 );
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for( i = nx - 1; i > 0; i-- )
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if( X[i] != 0 )
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break;
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j = biL - mpi_clz( X[i] );
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return( ( i * biL ) + j );
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}
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void mbedtls_mpi_mod_residue_release( mbedtls_mpi_mod_residue *r )
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{
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if ( r == NULL )
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return;
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r->n = 0;
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r->p = NULL;
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}
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int mbedtls_mpi_mod_residue_setup( mbedtls_mpi_mod_residue *r,
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mbedtls_mpi_mod_modulus *m,
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mbedtls_mpi_uint *X )
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{
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if( X == NULL || m == NULL || r == NULL || X >= m->p)
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return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
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r->n = m->n;
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r->p = X;
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return( 0 );
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}
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void mbedtls_mpi_mod_modulus_init( mbedtls_mpi_mod_modulus *m )
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{
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if ( m == NULL )
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return;
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m->rep.mont = 0;
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}
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void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m )
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{
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if ( m == NULL )
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return;
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m->p = NULL;
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m->n = 0;
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m->plen = 0;
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m->ext_rep = 0;
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m->int_rep = 0;
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m->rep.mont = NULL;
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m->rep.ored = NULL;
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}
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int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
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mbedtls_mpi_uint *X,
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size_t nx,
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int ext_rep,
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int int_rep )
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{
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if ( X == NULL || m == NULL )
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return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
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m->p = X;
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m->n = nx;
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m->ext_rep = ext_rep;
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m->int_rep = int_rep;
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m->plen = mpi_bitlen( X, nx );
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return( 0 );
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}
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#endif /* MBEDTLS_BIGNUM_C */
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