mbedtls/library/bignum_mod_raw.c
Gilles Peskine a57cf9813a Implement and test mbedtls_mpi_mod_raw_random
In the basic/XXX=core test cases, use odd upper bounds, because the mod
version of random() only supports odd upper bounds (the upper bound is a
modulus and the mod modules only support odd moduli).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2022-12-16 10:13:29 +01:00

254 lines
7.9 KiB
C

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