242 lines
7.5 KiB
C
242 lines
7.5 KiB
C
/*
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* Low-level modular 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 <string.h>
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#include "mbedtls/error.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/platform.h"
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#include "bignum_core.h"
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#include "bignum_mod_raw.h"
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#include "bignum_mod.h"
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#include "constant_time_internal.h"
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void mbedtls_mpi_mod_raw_cond_assign( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_mod_modulus *N,
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unsigned char assign )
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{
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mbedtls_mpi_core_cond_assign( X, A, N->limbs, assign );
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}
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void mbedtls_mpi_mod_raw_cond_swap( mbedtls_mpi_uint *X,
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mbedtls_mpi_uint *Y,
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const mbedtls_mpi_mod_modulus *N,
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unsigned char swap )
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{
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mbedtls_mpi_core_cond_swap( X, Y, N->limbs, swap );
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}
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int mbedtls_mpi_mod_raw_read( mbedtls_mpi_uint *X,
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const mbedtls_mpi_mod_modulus *m,
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const unsigned char *input,
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size_t input_length,
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mbedtls_mpi_mod_ext_rep ext_rep )
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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switch( ext_rep )
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{
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case MBEDTLS_MPI_MOD_EXT_REP_LE:
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ret = mbedtls_mpi_core_read_le( X, m->limbs,
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input, input_length );
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break;
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case MBEDTLS_MPI_MOD_EXT_REP_BE:
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ret = mbedtls_mpi_core_read_be( X, m->limbs,
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input, input_length );
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break;
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default:
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return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
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}
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if( ret != 0 )
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goto cleanup;
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if( !mbedtls_mpi_core_lt_ct( X, m->p, m->limbs ) )
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{
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ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
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goto cleanup;
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}
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cleanup:
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return( ret );
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}
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int mbedtls_mpi_mod_raw_write( const mbedtls_mpi_uint *A,
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const mbedtls_mpi_mod_modulus *m,
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unsigned char *output,
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size_t output_length,
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mbedtls_mpi_mod_ext_rep ext_rep )
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{
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switch( ext_rep )
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{
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case MBEDTLS_MPI_MOD_EXT_REP_LE:
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return( mbedtls_mpi_core_write_le( A, m->limbs,
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output, output_length ) );
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case MBEDTLS_MPI_MOD_EXT_REP_BE:
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return( mbedtls_mpi_core_write_be( A, m->limbs,
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output, output_length ) );
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default:
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return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
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}
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}
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/* BEGIN MERGE SLOT 1 */
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/* END MERGE SLOT 1 */
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/* BEGIN MERGE SLOT 2 */
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void mbedtls_mpi_mod_raw_sub( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *B,
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const mbedtls_mpi_mod_modulus *N )
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{
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mbedtls_mpi_uint c = mbedtls_mpi_core_sub( X, A, B, N->limbs );
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(void) mbedtls_mpi_core_add_if( X, N->p, N->limbs, (unsigned) c );
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}
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/* END MERGE SLOT 2 */
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/* BEGIN MERGE SLOT 3 */
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size_t mbedtls_mpi_mod_raw_inv_prime_working_limbs( size_t AN_limbs )
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{
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/* mbedtls_mpi_mod_raw_inv_prime() needs a temporary for the exponent,
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* which will be the same size as the modulus and input (AN_limbs),
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* and additional space to pass to mbedtls_mpi_core_exp_mod(). */
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return( AN_limbs +
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mbedtls_mpi_core_exp_mod_working_limbs( AN_limbs, AN_limbs ) );
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}
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void mbedtls_mpi_mod_raw_inv_prime( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *N,
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size_t AN_limbs,
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const mbedtls_mpi_uint *RR,
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mbedtls_mpi_uint *T )
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{
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/* Inversion by power: g^|G| = 1 => g^(-1) = g^(|G|-1), and
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* |G| = N - 1, so we want
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* g^(|G|-1) = g^(N - 2)
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*/
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/* Use the first AN_limbs of T to hold N - 2 */
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mbedtls_mpi_uint *Nminus2 = T;
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(void) mbedtls_mpi_core_sub_int( Nminus2, N, 2, AN_limbs );
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/* Rest of T is given to exp_mod for its working space */
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mbedtls_mpi_core_exp_mod( X,
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A, N, AN_limbs, Nminus2, AN_limbs,
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RR, T + AN_limbs );
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}
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/* END MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 4 */
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/* END MERGE SLOT 4 */
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/* BEGIN MERGE SLOT 5 */
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void mbedtls_mpi_mod_raw_add( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *B,
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const mbedtls_mpi_mod_modulus *N )
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{
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mbedtls_mpi_uint carry, borrow;
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carry = mbedtls_mpi_core_add( X, A, B, N->limbs );
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borrow = mbedtls_mpi_core_sub( X, X, N->p, N->limbs );
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(void) mbedtls_mpi_core_add_if( X, N->p, N->limbs, (unsigned) ( carry ^ borrow ) );
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}
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/* END MERGE SLOT 5 */
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/* BEGIN MERGE SLOT 6 */
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/* END MERGE SLOT 6 */
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/* BEGIN MERGE SLOT 7 */
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int mbedtls_mpi_mod_raw_to_mont_rep( mbedtls_mpi_uint *X,
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const mbedtls_mpi_mod_modulus *m )
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{
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mbedtls_mpi_uint *T;
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const size_t t_limbs = m->limbs * 2 + 1;
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if( ( T = (mbedtls_mpi_uint *) mbedtls_calloc( t_limbs, ciL ) ) == NULL )
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return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
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mbedtls_mpi_core_montmul( X, X, m->rep.mont.rr, m->limbs, m->p, m->limbs,
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m->rep.mont.mm, T );
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mbedtls_platform_zeroize( T, t_limbs * ciL );
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mbedtls_free( T );
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return( 0 );
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}
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int mbedtls_mpi_mod_raw_from_mont_rep( mbedtls_mpi_uint *X,
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const mbedtls_mpi_mod_modulus *m )
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{
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const mbedtls_mpi_uint one = 1;
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const size_t t_limbs = m->limbs * 2 + 1;
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mbedtls_mpi_uint *T;
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if( ( T = (mbedtls_mpi_uint *) mbedtls_calloc( t_limbs, ciL ) ) == NULL )
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return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
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mbedtls_mpi_core_montmul( X, X, &one, 1, m->p, m->limbs,
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m->rep.mont.mm, T );
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mbedtls_platform_zeroize( T, t_limbs * ciL );
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mbedtls_free( T );
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return( 0 );
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}
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void mbedtls_mpi_mod_raw_neg( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_mod_modulus *m )
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{
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mbedtls_mpi_core_sub( X, m->p, A, m->limbs );
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/* If A=0 initially, then X=N now. Detect this by
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* subtracting N and catching the carry. */
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mbedtls_mpi_uint borrow = mbedtls_mpi_core_sub( X, X, m->p, m->limbs );
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(void) mbedtls_mpi_core_add_if( X, m->p, m->limbs, (unsigned) borrow );
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}
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/* END MERGE SLOT 7 */
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/* BEGIN MERGE SLOT 8 */
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/* END MERGE SLOT 8 */
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/* BEGIN MERGE SLOT 9 */
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/* END MERGE SLOT 9 */
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/* BEGIN MERGE SLOT 10 */
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/* END MERGE SLOT 10 */
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#endif /* MBEDTLS_BIGNUM_C */
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