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

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_BIGNUM_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void mpi_mod_setup( 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, int_rep );
    TEST_EQUAL( ret, iret );

    /* Only test if the constants have been set-up  */
    if ( ret == 0 && int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
    {
        /* Test that the consts have been calculated */
        TEST_ASSERT( m.rep.mont.rr != NULL );
        TEST_ASSERT( m.rep.mont.mm != 0 );

    }

    /* 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 );

    /* Only test if the constants have been set-up  */
    if ( ret == 0 && int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
    {
        /* Verify the data and pointers allocated have been properly wiped */
        TEST_ASSERT( m.rep.mont.rr == NULL );
        TEST_ASSERT( m.rep.mont.mm == 0 );
    }
exit:
    /* It should be safe to call an mbedtls free several times */
    mbedtls_mpi_mod_modulus_free( &m );

    #undef MLIMBS
}
/* END_CASE */

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/* BEGIN_CASE */
void mpi_residue_setup( char * input_N, char * input_R, int ret )
{
    mbedtls_mpi_uint *N = NULL;
    mbedtls_mpi_uint *R = NULL;
    size_t n_limbs, r_limbs;
    mbedtls_mpi_mod_modulus m;
    mbedtls_mpi_mod_residue r;

    mbedtls_mpi_mod_modulus_init( &m );

    /* Allocate the memory for intermediate data structures */
    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &N, &n_limbs, input_N ) );
    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &R, &r_limbs, input_R ) );

    TEST_EQUAL( 0, mbedtls_mpi_mod_modulus_setup( &m, N, n_limbs,
                MBEDTLS_MPI_MOD_REP_MONTGOMERY ) );

    TEST_EQUAL( ret, mbedtls_mpi_mod_residue_setup( &r, &m, R , r_limbs ) );

    if ( ret == 0 )
    {
        TEST_EQUAL( r.limbs, r_limbs );
        TEST_ASSERT( r.p == R );
    }

exit:
    mbedtls_mpi_mod_modulus_free( &m );
    mbedtls_free( N );
    mbedtls_free( R );
}
/* END_CASE */

/* BEGIN_CASE */
void mpi_mod_io_neg( char * input_N, data_t * buf, int ret )
{
    mbedtls_mpi_uint *N = NULL;
    mbedtls_mpi_uint *R = NULL;

    mbedtls_mpi_mod_modulus m;
    mbedtls_mpi_mod_residue r = { NULL, 0 };
    mbedtls_mpi_mod_ext_rep endian = MBEDTLS_MPI_MOD_EXT_REP_LE;

    mbedtls_mpi_mod_modulus_init( &m );

    size_t n_limbs;
    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &N, &n_limbs, input_N ) );
    size_t r_limbs = n_limbs;
    ASSERT_ALLOC( R, r_limbs );

    /* modulus->p == NULL || residue->p == NULL ( m has not been set-up ) */
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );

    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );

    /* Set up modulus and test with residue->p == NULL */
    TEST_EQUAL( 0, mbedtls_mpi_mod_modulus_setup( &m, N, n_limbs,
                MBEDTLS_MPI_MOD_REP_MONTGOMERY ) );

    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );

    /* Do the rest of the tests with a residue set up with the input data */
    TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &r, &m, R , r_limbs ) );

    /* Fail for r_limbs < m->limbs */
    r.limbs--;
    TEST_ASSERT( r.limbs < m.limbs );
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );
    r.limbs++;

    /* Fail for r_limbs > m->limbs */
    m.limbs--;
    TEST_ASSERT( r.limbs > m.limbs );
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
    TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
                mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );
    m.limbs++;

    /* Test the read */
    TEST_EQUAL( ret, mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );

    /* Test write overflow only when the representation is large and read is successful  */
    if ( r.limbs > 1 && ret == 0 )
        TEST_EQUAL( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL,
                        mbedtls_mpi_mod_write( &r, &m, buf->x, 1, endian ) );

exit:
    mbedtls_mpi_mod_residue_release( &r );
    mbedtls_mpi_mod_modulus_free( &m );
    mbedtls_free( N );
    mbedtls_free( R );
}
/* END_CASE */

/* BEGIN_CASE */
void mpi_mod_io( char * input_N, data_t * input_A, int endian )
{
    mbedtls_mpi_uint *N = NULL;
    mbedtls_mpi_uint *R = NULL;
    mbedtls_mpi_uint *R_COPY = NULL;
    unsigned char *obuf = NULL;
    unsigned char *ref_buf = NULL;
    mbedtls_mpi_mod_modulus m;
    mbedtls_mpi_mod_residue r;
    mbedtls_mpi_mod_residue r_copy;
    size_t n_limbs, n_bytes, a_bytes;

    mbedtls_mpi_mod_modulus_init( &m );

    /* Read inputs */
    TEST_EQUAL( 0, mbedtls_test_read_mpi_core( &N, &n_limbs, input_N ) );
    n_bytes = n_limbs * sizeof( mbedtls_mpi_uint );
    a_bytes = input_A->len;

    /* Allocate the memory for intermediate data structures */
    ASSERT_ALLOC( R, n_bytes );
    ASSERT_ALLOC( R_COPY, n_bytes );

    /* Test that input's size is not greater to modulo's */
    TEST_LE_U( a_bytes, n_bytes );

    /* Init Structures */
    TEST_EQUAL( 0, mbedtls_mpi_mod_modulus_setup( &m, N, n_limbs,
                MBEDTLS_MPI_MOD_REP_MONTGOMERY ) );

    /* Enforcing p_limbs >= m->limbs */
    TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &r, &m, R, n_limbs ) );

    TEST_EQUAL( 0, mbedtls_mpi_mod_read( &r, &m, input_A->x, input_A->len,
                                         endian ) );

    /* Read a copy for checking that writing didn't change the value of r */
    TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &r_copy, &m,
                                                  R_COPY, n_limbs ) );
    TEST_EQUAL( 0, mbedtls_mpi_mod_read( &r_copy, &m, input_A->x, input_A->len,
                                         endian ) );

    /* Get number of bytes without leading zeroes */
    size_t a_bytes_trimmed = a_bytes;
    while( a_bytes_trimmed > 0 )
    {
        unsigned char* r_byte_array = (unsigned char*) r.p;
        if( r_byte_array[--a_bytes_trimmed] != 0 )
            break;
    }
    a_bytes_trimmed++;

    /* Test write with three output buffer sizes: tight, same as input and
     * longer than the input */
    size_t obuf_sizes[3];
    const size_t obuf_sizes_len = sizeof( obuf_sizes ) / sizeof( obuf_sizes[0] );
    obuf_sizes[0] = a_bytes_trimmed;
    obuf_sizes[1] = a_bytes;
    obuf_sizes[2] = a_bytes + 8;

    for( size_t i = 0; i < obuf_sizes_len; i++ )
    {
        ASSERT_ALLOC( obuf, obuf_sizes[i] );
        TEST_EQUAL( 0, mbedtls_mpi_mod_write( &r, &m, obuf, obuf_sizes[i], endian ) );

        /* Make sure that writing didn't corrupt the value of r */
        ASSERT_COMPARE( r.p, r.limbs, r_copy.p, r_copy.limbs );

        /* Set up reference output for checking the result */
        ASSERT_ALLOC( ref_buf, obuf_sizes[i] );
        switch( endian )
        {
            case MBEDTLS_MPI_MOD_EXT_REP_LE:
                memcpy( ref_buf, input_A->x, a_bytes_trimmed );
                break;
            case MBEDTLS_MPI_MOD_EXT_REP_BE:
                {
                    size_t a_offset = input_A->len - a_bytes_trimmed;
                    size_t ref_offset = obuf_sizes[i] - a_bytes_trimmed;
                    memcpy( ref_buf + ref_offset, input_A->x + a_offset,
                            a_bytes_trimmed );
                }
                break;
            default:
                TEST_ASSERT( 0 );
        }

        /* Check the result */
        ASSERT_COMPARE( obuf, obuf_sizes[i], ref_buf, obuf_sizes[i] );

        mbedtls_free( ref_buf );
        ref_buf = NULL;
        mbedtls_free( obuf );
        obuf = NULL;
    }

exit:
    mbedtls_mpi_mod_modulus_free( &m );
    mbedtls_free( N );
    mbedtls_free( R );
    mbedtls_free( R_COPY );
    mbedtls_free( obuf );
}
/* END_CASE */
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