/* BEGIN_HEADER */
#include "mbedtls/ctr_drbg.h"
#include "string.h"

static int test_offset_idx;
static int mbedtls_test_entropy_func( void *data, unsigned char *buf, size_t len )
{
    const unsigned char *p = (unsigned char *) data;
    memcpy( buf, p + test_offset_idx, len );
    test_offset_idx += len;
    return( 0 );
}
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_CTR_DRBG_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void ctr_drbg_special_behaviours(  )
{
    mbedtls_ctr_drbg_context ctx;
    unsigned char output[512];
    unsigned char additional[512];

    mbedtls_ctr_drbg_init( &ctx );
    memset( output, 0, sizeof( output ) );
    memset( additional, 0, sizeof( additional ) );

    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx,
                        output, MBEDTLS_CTR_DRBG_MAX_REQUEST + 1,
                        additional, 16 ) ==
                        MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG );
    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx,
                        output, 16,
                        additional, MBEDTLS_CTR_DRBG_MAX_INPUT + 1 ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    TEST_ASSERT( mbedtls_ctr_drbg_reseed( &ctx, additional,
                        MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + 1 ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    mbedtls_ctr_drbg_set_entropy_len( &ctx, ~0 );
    TEST_ASSERT( mbedtls_ctr_drbg_reseed( &ctx, additional,
                        MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate_pr( data_t * add_init, data_t * entropy,
                           data_t * add1, data_t * add2,
                           data_t * result_str )
{
    mbedtls_ctr_drbg_context ctx;
    unsigned char buf[512];

    mbedtls_ctr_drbg_init( &ctx );


    test_offset_idx = 0;
    /* CTR_DRBG_Instantiate(entropy[:entropy_len/3], nonce, perso, <ignored>)
     * where nonce||perso = add_init[add_init_len] */
    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );

    /* CTR_DRBG_Generate(result_len * 8 bits, add1[:add1_len]) -> buf */
    /* Then reseed because of prediction resistance. */
    TEST_ASSERT( hexcmp( buf, result_str->x, 16, result_str->len ) == 0 );
    /* CTR_DRBG_Generate(result_len * 8 bits, add2[:add2_len]) -> buf */
    /* Then reseed because of prediction resistance. */

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate_nopr( data_t * add_init, data_t * entropy,
                             data_t * add1, data_t * add_reseed,
                             data_t * add2, data_t * result_str )
{
    mbedtls_ctr_drbg_context ctx;
    unsigned char buf[512];

    mbedtls_ctr_drbg_init( &ctx );


    test_offset_idx = 0;
    /* CTR_DRBG_Instantiate(entropy[:entropy_len/2], nonce, perso, <ignored>)
     * where nonce||perso = add_init[add_init_len] */

    /* CTR_DRBG_Generate(16 * 8 bits, add1[:add1_len]) -> buf */
    TEST_ASSERT( mbedtls_ctr_drbg_reseed( &ctx, add_reseed->x, add_reseed->len ) == 0 );
    /* CTR_DRBG_Reseed(entropy[entropy_len/2:entropy_len], add_reseed[:add_reseed_len]) */
    TEST_ASSERT( hexcmp( buf, result_str->x, 16, result_str->len ) == 0 );
    /* CTR_DRBG_Generate(16 * 8 bits, add2[:add2_len]) -> buf */

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_entropy_usage(  )
{
    unsigned char out[16];
    unsigned char add[16];
    unsigned char entropy[1024];
    mbedtls_ctr_drbg_context ctx;
    size_t i, reps = 10;
    int last_idx;

    mbedtls_ctr_drbg_init( &ctx );
    test_offset_idx = 0;
    memset( entropy, 0, sizeof( entropy ) );
    memset( out, 0, sizeof( out ) );
    memset( add, 0, sizeof( add ) );

    /* Init must use entropy */
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_seed( &ctx, mbedtls_test_entropy_func, entropy, NULL, 0 ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* By default, PR is off and reseed_interval is large,
     * so the next few calls should not use entropy */
    last_idx = test_offset_idx;
    for( i = 0; i < reps; i++ )
    {
        TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) - 4 ) == 0 );
        TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, out, sizeof( out ) - 4,
                                                add, sizeof( add ) ) == 0 );
    }
    TEST_ASSERT( last_idx == test_offset_idx );

    /* While at it, make sure we didn't write past the requested length */
    TEST_ASSERT( out[sizeof( out ) - 4] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 3] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 2] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 1] == 0 );

    /* Set reseed_interval to the number of calls done,
     * so the next call should reseed */
    mbedtls_ctr_drbg_set_reseed_interval( &ctx, 2 * reps );
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* The new few calls should not reseed */
    last_idx = test_offset_idx;
    for( i = 0; i < reps / 2; i++ )
    {
        TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
        TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, out, sizeof( out ) ,
                                                add, sizeof( add ) ) == 0 );
    }
    TEST_ASSERT( last_idx == test_offset_idx );

    /* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT)
     * (just make sure it doesn't cause memory corruption) */
    mbedtls_ctr_drbg_update( &ctx, entropy, sizeof( entropy ) );

    /* Now enable PR, so the next few calls should all reseed */
    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* Finally, check setting entropy_len */
    mbedtls_ctr_drbg_set_entropy_len( &ctx, 42 );
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( test_offset_idx - last_idx == 42 );

    mbedtls_ctr_drbg_set_entropy_len( &ctx, 13 );
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( test_offset_idx - last_idx == 13 );

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_FS_IO */
void ctr_drbg_seed_file( char * path, int ret )
{
    mbedtls_ctr_drbg_context ctx;

    mbedtls_ctr_drbg_init( &ctx );

    TEST_ASSERT( mbedtls_ctr_drbg_seed( &ctx, rnd_std_rand, NULL, NULL, 0 ) == 0 );
    TEST_ASSERT( mbedtls_ctr_drbg_write_seed_file( &ctx, path ) == ret );
    TEST_ASSERT( mbedtls_ctr_drbg_update_seed_file( &ctx, path ) == ret );

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
void ctr_drbg_selftest(  )
{
    TEST_ASSERT( mbedtls_ctr_drbg_self_test( 1 ) == 0 );
}
/* END_CASE */