tests/suites/test_suite_bignum_mod.function

/* BEGIN_HEADER */
#include "mbedtls/bignum.h"
#include "mbedtls/entropy.h"
#include "bignum_mod.h"
#include "constant_time_internal.h"
#include "test/constant_flow.h"

/* Check the validity of the sign bit in an MPI object. Reject representations
 * that are not supported by the rest of the library and indicate a bug when
 * constructing the value. */
static int sign_is_valid( const mbedtls_mpi *X )
{
    if( X->s != 1 && X->s != -1 )
        return( 0 ); // invalid sign bit, e.g. 0
    if( mbedtls_mpi_bitlen( X ) == 0 && X->s != 1 )
        return( 0 ); // negative zero
    return( 1 );
}

/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_BIGNUM_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void mpi_mod_setup( int ext_rep, int int_rep, int iret )
{
    #define MLIMBS 8
    mbedtls_mpi_uint mp[MLIMBS];
    mbedtls_mpi_mod_modulus m;
    int ret;

    memset( mp, 0xFF, sizeof(mp) );

    mbedtls_mpi_mod_modulus_init( &m );
    ret = mbedtls_mpi_mod_modulus_setup( &m, mp, MLIMBS, ext_rep, int_rep );
    TEST_EQUAL( ret, iret );

    /* Address sanitiser should catch if we try to free mp */
    mbedtls_mpi_mod_modulus_free( &m );

    /* Make sure that the modulus doesn't have reference to mp anymore */
    TEST_ASSERT( m.p != mp );

exit:
    /* It should be safe to call an mbedtls free several times */
    mbedtls_mpi_mod_modulus_free( &m );

    #undef MLIMBS
}
/* END_CASE */


/* BEGIN_CASE */
void mpi_mod_mpi( char * input_X, char * input_Y,
                  char * input_A, int div_result )
{
    mbedtls_mpi X, Y, A;
    int res;
    mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y ); mbedtls_mpi_init( &A );

    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
    TEST_ASSERT( mbedtls_test_read_mpi( &Y, input_Y ) == 0 );
    TEST_ASSERT( mbedtls_test_read_mpi( &A, input_A ) == 0 );
    res = mbedtls_mpi_mod_mpi( &X, &X, &Y );
    TEST_ASSERT( res == div_result );
    if( res == 0 )
    {
        TEST_ASSERT( sign_is_valid( &X ) );
        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
    }

exit:
    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &A );
}
/* END_CASE */

/* BEGIN_CASE */
void mpi_mod_int( char * input_X, int input_Y,
                  int input_A, int div_result )
{
    mbedtls_mpi X;
    int res;
    mbedtls_mpi_uint r;
    mbedtls_mpi_init( &X );

    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
    res = mbedtls_mpi_mod_int( &r, &X, input_Y );
    TEST_ASSERT( res == div_result );
    if( res == 0 )
    {
        TEST_ASSERT( r == (mbedtls_mpi_uint) input_A );
    }

exit:
    mbedtls_mpi_free( &X );
}
/* END_CASE */