mbedtls/tests/suites/test_suite_cipher.function

/* BEGIN_HEADER */
#include "mbedtls/cipher.h"
#include "mbedtls/aes.h"

#if defined(MBEDTLS_GCM_C)
#include "mbedtls/gcm.h"
#endif

#if defined(MBEDTLS_CIPHER_MODE_AEAD) || defined(MBEDTLS_NIST_KW_C)
#define MBEDTLS_CIPHER_AUTH_CRYPT
#endif

/* Check the internal consistency of a cipher info structure, and
 * check it against mbedtls_cipher_info_from_xxx(). */
static int check_cipher_info( mbedtls_cipher_type_t type,
                              const mbedtls_cipher_info_t *info )
{
    size_t key_bitlen, block_size, iv_size;

    TEST_ASSERT( info != NULL );
    TEST_EQUAL( type, mbedtls_cipher_info_get_type( info ) );
    TEST_EQUAL( type, info->type );
    TEST_ASSERT( mbedtls_cipher_info_from_type( type ) == info );

    TEST_EQUAL( info->mode, mbedtls_cipher_info_get_mode( info ) );

    /* Insist that get_name() return the string from the structure and
     * not a copy. A copy would have an unknown storage duration. */
    TEST_ASSERT( mbedtls_cipher_info_get_name( info ) == info->name );
    TEST_ASSERT( mbedtls_cipher_info_from_string( info->name ) == info );

    key_bitlen = mbedtls_cipher_info_get_key_bitlen( info );
    block_size = mbedtls_cipher_info_get_block_size( info );
    iv_size = mbedtls_cipher_info_get_iv_size( info );
    if( info->type == MBEDTLS_CIPHER_NULL )
    {
        TEST_ASSERT( key_bitlen == 0 );
        TEST_ASSERT( block_size == 1 );
        TEST_ASSERT( iv_size == 0 );
    }
    else if( info->mode == MBEDTLS_MODE_XTS )
    {
        TEST_ASSERT( key_bitlen == 256 ||
                     key_bitlen == 384 ||
                     key_bitlen == 512 );
    }
    else if( ! strncmp( info->name, "DES-EDE3-", 9 ) )
    {
        TEST_ASSERT( key_bitlen == 192 );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_key_bitlen( info ) );
        TEST_ASSERT( block_size == 8 );
    }
    else if( ! strncmp( info->name, "DES-EDE-", 8 ) )
    {
        TEST_ASSERT( key_bitlen == 128 );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_key_bitlen( info ) );
        TEST_ASSERT( block_size == 8 );
    }
    else if( ! strncmp( info->name, "DES-", 4 ) )
    {
        TEST_ASSERT( key_bitlen == 64 );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_key_bitlen( info ) );
        TEST_ASSERT( block_size == 8 );
    }
    else if( ! strncmp( info->name, "AES", 3 ) )
    {
        TEST_ASSERT( key_bitlen == 128 ||
                     key_bitlen == 192 ||
                     key_bitlen == 256 );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_key_bitlen( info ) );
        TEST_ASSERT( block_size == 16 );
    }
    else
    {
        TEST_ASSERT( key_bitlen == 128 ||
                     key_bitlen == 192 ||
                     key_bitlen == 256 );
    }

    if( strstr( info->name, "-ECB" ) != NULL )
    {
        TEST_ASSERT( iv_size == 0 );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_iv_size( info ) );
    }
    else if( strstr( info->name, "-CBC" ) != NULL ||
             strstr( info->name, "-CTR" ) != NULL )
    {
        TEST_ASSERT( iv_size == block_size );
        TEST_ASSERT( ! mbedtls_cipher_info_has_variable_iv_size( info ) );
    }
    else if( strstr( info->name, "-GCM" ) != NULL )
    {
        TEST_ASSERT( iv_size == block_size - 4 );
        TEST_ASSERT( mbedtls_cipher_info_has_variable_iv_size( info ) );
    }

    return( 1 );

exit:
    return( 0 );
}

#if defined(MBEDTLS_CIPHER_AUTH_CRYPT)
/* Helper for resetting key/direction
 *
 * The documentation doesn't explicitly say whether calling
 * mbedtls_cipher_setkey() twice is allowed or not. This currently works with
 * the default software implementation, but only by accident. It isn't
 * guaranteed to work with new ciphers or with alternative implementations of
 * individual ciphers, and it doesn't work with the PSA wrappers. So don't do
 * it, and instead start with a fresh context.
 */
static int cipher_reset_key( mbedtls_cipher_context_t *ctx, int cipher_id,
        int use_psa, size_t tag_len, const data_t *key, int direction )
{
    mbedtls_cipher_free( ctx );
    mbedtls_cipher_init( ctx );

#if !defined(MBEDTLS_USE_PSA_CRYPTO) || !defined(MBEDTLS_TEST_DEPRECATED)
    (void) use_psa;
    (void) tag_len;
#else
    if( use_psa == 1 )
    {
        TEST_ASSERT( 0 == mbedtls_cipher_setup_psa( ctx,
                              mbedtls_cipher_info_from_type( cipher_id ),
                              tag_len ) );
    }
    else
#endif /* !MBEDTLS_USE_PSA_CRYPTO || !MBEDTLS_TEST_DEPRECATED */
    {
        TEST_ASSERT( 0 == mbedtls_cipher_setup( ctx,
                              mbedtls_cipher_info_from_type( cipher_id ) ) );
    }

    TEST_ASSERT( 0 == mbedtls_cipher_setkey( ctx, key->x, 8 * key->len,
                                             direction ) );
    return( 1 );

exit:
    return( 0 );
}

/*
 * Check if a buffer is all-0 bytes:
 * return   1 if it is,
 *          0 if it isn't.
 */
int buffer_is_all_zero( const uint8_t *buf, size_t size )
{
    for( size_t i = 0; i < size; i++ )
        if( buf[i] != 0 )
            return 0;
    return 1;
}
#endif /* MBEDTLS_CIPHER_AUTH_CRYPT */

/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_CIPHER_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void mbedtls_cipher_list(  )
{
    const int *cipher_type;

    for( cipher_type = mbedtls_cipher_list(); *cipher_type != 0; cipher_type++ )
    {
        const mbedtls_cipher_info_t *info =
            mbedtls_cipher_info_from_type( *cipher_type );
        mbedtls_test_set_step( *cipher_type );
        if( ! check_cipher_info( *cipher_type, info ) )
            goto exit;
    }
}
/* END_CASE */

/* BEGIN_CASE */
void cipher_invalid_param_unconditional( )
{
    mbedtls_cipher_context_t valid_ctx;
    mbedtls_cipher_context_t invalid_ctx;
    mbedtls_operation_t valid_operation = MBEDTLS_ENCRYPT;
    mbedtls_cipher_padding_t valid_mode = MBEDTLS_PADDING_ZEROS;
    unsigned char valid_buffer[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 };
    int valid_size = sizeof(valid_buffer);
    int valid_bitlen = valid_size * 8;
    const mbedtls_cipher_info_t *valid_info = mbedtls_cipher_info_from_type(
        *( mbedtls_cipher_list() ) );
    size_t size_t_var;

    (void)valid_mode; /* In some configurations this is unused */

    mbedtls_cipher_init( &valid_ctx );
    mbedtls_cipher_init( &invalid_ctx );

    TEST_ASSERT( mbedtls_cipher_setup( &valid_ctx, valid_info ) == 0 );

    /* mbedtls_cipher_setup() */
    TEST_ASSERT( mbedtls_cipher_setup( &valid_ctx, NULL ) ==
                 MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    /* mbedtls_cipher_get_block_size() */
    TEST_ASSERT( mbedtls_cipher_get_block_size( &invalid_ctx ) == 0 );

    /* mbedtls_cipher_get_cipher_mode() */
    TEST_ASSERT( mbedtls_cipher_get_cipher_mode( &invalid_ctx ) ==
                 MBEDTLS_MODE_NONE );

    /* mbedtls_cipher_get_iv_size() */
    TEST_ASSERT( mbedtls_cipher_get_iv_size( &invalid_ctx ) == 0 );

    /* mbedtls_cipher_get_type() */
    TEST_ASSERT(
        mbedtls_cipher_get_type( &invalid_ctx ) ==
        MBEDTLS_CIPHER_NONE);

    /* mbedtls_cipher_get_name() */
    TEST_ASSERT( mbedtls_cipher_get_name( &invalid_ctx ) == 0 );

    /* mbedtls_cipher_get_key_bitlen() */
    TEST_ASSERT( mbedtls_cipher_get_key_bitlen( &invalid_ctx ) ==
                 MBEDTLS_KEY_LENGTH_NONE );

    /* mbedtls_cipher_get_operation() */
    TEST_ASSERT( mbedtls_cipher_get_operation( &invalid_ctx ) ==
                 MBEDTLS_OPERATION_NONE );

    /* mbedtls_cipher_setkey() */
    TEST_ASSERT(
        mbedtls_cipher_setkey( &invalid_ctx,
                               valid_buffer,
                               valid_bitlen,
                               valid_operation ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    /* mbedtls_cipher_set_iv() */
    TEST_ASSERT(
        mbedtls_cipher_set_iv( &invalid_ctx,
                               valid_buffer,
                               valid_size ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    /* mbedtls_cipher_reset() */
    TEST_ASSERT( mbedtls_cipher_reset( &invalid_ctx ) ==
                 MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    /* mbedtls_cipher_update_ad() */
    TEST_ASSERT(
        mbedtls_cipher_update_ad( &invalid_ctx,
                                  valid_buffer,
                                  valid_size ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
#endif /* defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C) */

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    /* mbedtls_cipher_set_padding_mode() */
    TEST_ASSERT( mbedtls_cipher_set_padding_mode( &invalid_ctx, valid_mode ) ==
                 MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
#endif

    /* mbedtls_cipher_update() */
    TEST_ASSERT(
        mbedtls_cipher_update( &invalid_ctx,
                               valid_buffer,
                               valid_size,
                               valid_buffer,
                               &size_t_var ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    /* mbedtls_cipher_finish() */
    TEST_ASSERT(
        mbedtls_cipher_finish( &invalid_ctx,
                               valid_buffer,
                               &size_t_var ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    /* mbedtls_cipher_write_tag() */
    TEST_ASSERT(
        mbedtls_cipher_write_tag( &invalid_ctx,
                                  valid_buffer,
                                  valid_size ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    /* mbedtls_cipher_check_tag() */
    TEST_ASSERT(
        mbedtls_cipher_check_tag( &invalid_ctx,
                                  valid_buffer,
                                  valid_size ) ==
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
#endif /* defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C) */

exit:
    mbedtls_cipher_free( &invalid_ctx );
    mbedtls_cipher_free( &valid_ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void cipher_invalid_param_conditional( )
{
    mbedtls_cipher_context_t valid_ctx;

    mbedtls_operation_t invalid_operation = 100;
    unsigned char valid_buffer[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 };
    int valid_size = sizeof(valid_buffer);
    int valid_bitlen = valid_size * 8;

    TEST_EQUAL(
        MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA,
        mbedtls_cipher_setkey( &valid_ctx,
                               valid_buffer,
                               valid_bitlen,
                               invalid_operation ) );

exit:
    ;
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_AES_C */
void cipher_special_behaviours(  )
{
    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_cipher_context_t ctx;
    unsigned char input[32];
    unsigned char output[32];
#if defined (MBEDTLS_CIPHER_MODE_CBC)
    unsigned char iv[32];
#endif
    size_t olen = 0;

    mbedtls_cipher_init( &ctx );
    memset( input, 0, sizeof( input ) );
    memset( output, 0, sizeof( output ) );
#if defined(MBEDTLS_CIPHER_MODE_CBC)
    memset( iv, 0, sizeof( iv ) );

    /* Check and get info structures */
    cipher_info = mbedtls_cipher_info_from_type( MBEDTLS_CIPHER_AES_128_CBC );
    TEST_ASSERT( NULL != cipher_info );

    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx, cipher_info ) );

    /* IV too big */
    TEST_ASSERT( mbedtls_cipher_set_iv( &ctx, iv, MBEDTLS_MAX_IV_LENGTH + 1 )
                 == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );

    /* IV too small */
    TEST_ASSERT( mbedtls_cipher_set_iv( &ctx, iv, 0 )
                 == MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

    mbedtls_cipher_free( &ctx );
    mbedtls_cipher_init( &ctx );
#endif /* MBEDTLS_CIPHER_MODE_CBC */
    cipher_info = mbedtls_cipher_info_from_type( MBEDTLS_CIPHER_AES_128_ECB );
    TEST_ASSERT( NULL != cipher_info );

    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx, cipher_info ) );

    /* Update ECB with partial block */
    TEST_ASSERT( mbedtls_cipher_update( &ctx, input, 1, output, &olen )
                 == MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED );

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

/* BEGIN_CASE */
void enc_dec_buf( int cipher_id, char * cipher_string, int key_len,
                  int length_val, int pad_mode )
{
    size_t length = length_val, outlen, total_len, i, block_size, iv_len;
    unsigned char key[64];
    unsigned char iv[16];
    unsigned char ad[13];
    unsigned char tag[16];
    unsigned char inbuf[64];
    unsigned char encbuf[64];
    unsigned char decbuf[64];

    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_cipher_context_t ctx_dec;
    mbedtls_cipher_context_t ctx_enc;

    /*
     * Prepare contexts
     */
    mbedtls_cipher_init( &ctx_dec );
    mbedtls_cipher_init( &ctx_enc );

    memset( key, 0x2a, sizeof( key ) );

    /* Check and get info structures */
    cipher_info = mbedtls_cipher_info_from_type( cipher_id );
    TEST_ASSERT( NULL != cipher_info );
    TEST_ASSERT( mbedtls_cipher_info_from_string( cipher_string ) == cipher_info );
    TEST_ASSERT( strcmp( mbedtls_cipher_info_get_name( cipher_info ),
                         cipher_string ) == 0 );

    /* Initialise enc and dec contexts */
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_dec, cipher_info ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_enc, cipher_info ) );

    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx_dec, key, key_len, MBEDTLS_DECRYPT ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx_enc, key, key_len, MBEDTLS_ENCRYPT ) );

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    if( -1 != pad_mode )
    {
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx_dec, pad_mode ) );
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx_enc, pad_mode ) );
    }
#else
    (void) pad_mode;
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

    /*
     * Do a few encode/decode cycles
     */
    for( i = 0; i < 3; i++ )
    {
    memset( iv , 0x00 + i, sizeof( iv ) );
    memset( ad, 0x10 + i, sizeof( ad ) );
    memset( inbuf, 0x20 + i, sizeof( inbuf ) );

    memset( encbuf, 0, sizeof( encbuf ) );
    memset( decbuf, 0, sizeof( decbuf ) );
    memset( tag, 0, sizeof( tag ) );

    if( NULL != strstr( cipher_info->name, "CCM*-NO-TAG") )
        iv_len = 13; /* For CCM, IV length is expected to be between 7 and 13 bytes.
                      * For CCM*-NO-TAG, IV length must be exactly 13 bytes long. */
    else if( cipher_info->type == MBEDTLS_CIPHER_CHACHA20 ||
             cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 )
        iv_len = 12;
    else
        iv_len = sizeof(iv);

    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx_dec, iv, iv_len ) );
    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx_enc, iv, iv_len ) );

    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx_dec ) );
    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx_enc ) );

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int expected = ( cipher_info->mode == MBEDTLS_MODE_GCM ||
                     cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                   0 : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx_dec, ad, sizeof(ad) - i ) );
    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx_enc, ad, sizeof(ad) - i ) );
#endif

    block_size = mbedtls_cipher_get_block_size( &ctx_enc );
    TEST_ASSERT( block_size != 0 );

    /* encode length number of bytes from inbuf */
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_enc, inbuf, length, encbuf, &outlen ) );
    total_len = outlen;

    TEST_ASSERT( total_len == length ||
                 ( total_len % block_size == 0 &&
                   total_len < length &&
                   total_len + block_size > length ) );

    TEST_ASSERT( 0 == mbedtls_cipher_finish( &ctx_enc, encbuf + outlen, &outlen ) );
    total_len += outlen;

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    TEST_EQUAL( expected, mbedtls_cipher_write_tag( &ctx_enc, tag, sizeof(tag) ) );
#endif

    TEST_ASSERT( total_len == length ||
                 ( total_len % block_size == 0 &&
                   total_len > length &&
                   total_len <= length + block_size ) );

    /* decode the previously encoded string */
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_dec, encbuf, total_len, decbuf, &outlen ) );
    total_len = outlen;

    TEST_ASSERT( total_len == length ||
                 ( total_len % block_size == 0 &&
                   total_len < length &&
                   total_len + block_size >= length ) );

    TEST_ASSERT( 0 == mbedtls_cipher_finish( &ctx_dec, decbuf + outlen, &outlen ) );
    total_len += outlen;

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    TEST_EQUAL( expected, mbedtls_cipher_check_tag( &ctx_dec, tag, sizeof(tag) ) );
#endif

    /* check result */
    TEST_ASSERT( total_len == length );
    TEST_ASSERT( 0 == memcmp(inbuf, decbuf, length) );
    }

    /*
     * Done
     */
exit:
    mbedtls_cipher_free( &ctx_dec );
    mbedtls_cipher_free( &ctx_enc );
}
/* END_CASE */

/* BEGIN_CASE */
void enc_fail( int cipher_id, int pad_mode, int key_len, int length_val,
               int ret )
{
    size_t length = length_val;
    unsigned char key[32];
    unsigned char iv[16];

    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_cipher_context_t ctx;

    unsigned char inbuf[64];
    unsigned char encbuf[64];

    size_t outlen = 0;

    memset( key, 0, 32 );
    memset( iv , 0, 16 );

    mbedtls_cipher_init( &ctx );

    memset( inbuf, 5, 64 );
    memset( encbuf, 0, 64 );

    /* Check and get info structures */
    cipher_info = mbedtls_cipher_info_from_type( cipher_id );
    TEST_ASSERT( NULL != cipher_info );

    /* Initialise context */
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx, cipher_info ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx, key, key_len, MBEDTLS_ENCRYPT ) );
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx, pad_mode ) );
#else
    (void) pad_mode;
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx, iv, 16 ) );
    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx ) );
#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int expected = ( cipher_info->mode == MBEDTLS_MODE_GCM ||
                     cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                   0 : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx, NULL, 0 ) );
#endif

    /* encode length number of bytes from inbuf */
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx, inbuf, length, encbuf, &outlen ) );
    TEST_ASSERT( ret == mbedtls_cipher_finish( &ctx, encbuf + outlen, &outlen ) );

    /* done */
exit:
    mbedtls_cipher_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void dec_empty_buf( int cipher,
                    int expected_update_ret,
                    int expected_finish_ret )
{
    unsigned char key[32];

    unsigned char *iv = NULL;
    size_t iv_len = 16;

    mbedtls_cipher_context_t ctx_dec;
    const mbedtls_cipher_info_t *cipher_info;

    unsigned char encbuf[64];
    unsigned char decbuf[64];

    size_t outlen = 0;

    memset( key, 0, 32 );

    mbedtls_cipher_init( &ctx_dec );

    memset( encbuf, 0, 64 );
    memset( decbuf, 0, 64 );

    /* Initialise context */
    cipher_info = mbedtls_cipher_info_from_type( cipher );
    TEST_ASSERT( NULL != cipher_info);

    if( cipher_info->type == MBEDTLS_CIPHER_CHACHA20 ||
        cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 )
        iv_len = 12;

    ASSERT_ALLOC( iv, iv_len );
    memset( iv , 0, iv_len );

    TEST_ASSERT( sizeof(key) * 8 >= cipher_info->key_bitlen );

    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_dec, cipher_info ) );

    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx_dec,
                                             key, cipher_info->key_bitlen,
                                             MBEDTLS_DECRYPT ) );

    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx_dec, iv, iv_len ) );

    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx_dec ) );

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int expected = ( cipher_info->mode == MBEDTLS_MODE_GCM ||
                     cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                   0 : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx_dec, NULL, 0 ) );
#endif

    /* decode 0-byte string */
    TEST_ASSERT( expected_update_ret ==
                 mbedtls_cipher_update( &ctx_dec, encbuf, 0, decbuf, &outlen ) );
    TEST_ASSERT( 0 == outlen );

    if ( expected_finish_ret == 0 &&
         ( cipher_info->mode == MBEDTLS_MODE_CBC ||
           cipher_info->mode == MBEDTLS_MODE_ECB ) )
    {
        /* Non-CBC and non-ECB ciphers are OK with decrypting empty buffers and
         * return success, not MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED, when
         * decrypting an empty buffer.
         * On the other hand, CBC and ECB ciphers need a full block of input.
         */
        expected_finish_ret = MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED;
    }

    TEST_ASSERT( expected_finish_ret == mbedtls_cipher_finish(
                                        &ctx_dec, decbuf + outlen, &outlen ) );
    TEST_ASSERT( 0 == outlen );

exit:
    mbedtls_free( iv );
    mbedtls_cipher_free( &ctx_dec );
}
/* END_CASE */

/* BEGIN_CASE */
void enc_dec_buf_multipart( int cipher_id, int key_len, int first_length_val,
                            int second_length_val, int pad_mode,
                            int first_encrypt_output_len, int second_encrypt_output_len,
                            int first_decrypt_output_len, int second_decrypt_output_len )
{
    size_t first_length = first_length_val;
    size_t second_length = second_length_val;
    size_t length = first_length + second_length;
    size_t block_size;
    size_t iv_len;
    unsigned char key[32];
    unsigned char iv[16];

    mbedtls_cipher_context_t ctx_dec;
    mbedtls_cipher_context_t ctx_enc;
    const mbedtls_cipher_info_t *cipher_info;

    unsigned char inbuf[64];
    unsigned char encbuf[64];
    unsigned char decbuf[64];

    size_t outlen = 0;
    size_t totaloutlen = 0;

    memset( key, 0, 32 );
    memset( iv , 0, 16 );

    mbedtls_cipher_init( &ctx_dec );
    mbedtls_cipher_init( &ctx_enc );

    memset( inbuf, 5, 64 );
    memset( encbuf, 0, 64 );
    memset( decbuf, 0, 64 );

    /* Initialise enc and dec contexts */
    cipher_info = mbedtls_cipher_info_from_type( cipher_id );
    TEST_ASSERT( NULL != cipher_info);

    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_dec, cipher_info ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_enc, cipher_info ) );

    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx_dec, key, key_len, MBEDTLS_DECRYPT ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx_enc, key, key_len, MBEDTLS_ENCRYPT ) );

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    if( -1 != pad_mode )
    {
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx_dec, pad_mode ) );
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx_enc, pad_mode ) );
    }
#else
    (void) pad_mode;
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

    if( NULL != strstr( cipher_info->name, "CCM*-NO-TAG") )
        iv_len = 13; /* For CCM, IV length is expected to be between 7 and 13 bytes.
                      * For CCM*-NO-TAG, IV length must be exactly 13 bytes long. */
    else if( cipher_info->type == MBEDTLS_CIPHER_CHACHA20 ||
             cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 )
        iv_len = 12;
    else
        iv_len = sizeof(iv);

    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx_dec, iv, iv_len ) );
    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx_enc, iv, iv_len ) );

    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx_dec ) );
    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx_enc ) );

#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int expected = ( cipher_info->mode == MBEDTLS_MODE_GCM ||
                     cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                   0 : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx_dec, NULL, 0 ) );
    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx_enc, NULL, 0 ) );
#endif

    block_size = mbedtls_cipher_get_block_size( &ctx_enc );
    TEST_ASSERT( block_size != 0 );

    /* encode length number of bytes from inbuf */
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_enc, inbuf, first_length, encbuf, &outlen ) );
    TEST_ASSERT( (size_t)first_encrypt_output_len == outlen );
    totaloutlen = outlen;
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_enc, inbuf + first_length, second_length, encbuf + totaloutlen, &outlen ) );
    TEST_ASSERT( (size_t)second_encrypt_output_len == outlen );
    totaloutlen += outlen;
    TEST_ASSERT( totaloutlen == length ||
                 ( totaloutlen % block_size == 0 &&
                   totaloutlen < length &&
                   totaloutlen + block_size > length ) );

    TEST_ASSERT( 0 == mbedtls_cipher_finish( &ctx_enc, encbuf + totaloutlen, &outlen ) );
    totaloutlen += outlen;
    TEST_ASSERT( totaloutlen == length ||
                 ( totaloutlen % block_size == 0 &&
                   totaloutlen > length &&
                   totaloutlen <= length + block_size ) );

    /* decode the previously encoded string */
    second_length = totaloutlen - first_length;
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_dec, encbuf, first_length, decbuf, &outlen ) );
    TEST_ASSERT( (size_t)first_decrypt_output_len == outlen );
    totaloutlen = outlen;
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx_dec, encbuf + first_length, second_length, decbuf + totaloutlen, &outlen ) );
    TEST_ASSERT( (size_t)second_decrypt_output_len == outlen );
    totaloutlen += outlen;

    TEST_ASSERT( totaloutlen == length ||
                 ( totaloutlen % block_size == 0 &&
                   totaloutlen < length &&
                   totaloutlen + block_size >= length ) );

    TEST_ASSERT( 0 == mbedtls_cipher_finish( &ctx_dec, decbuf + totaloutlen, &outlen ) );
    totaloutlen += outlen;

    TEST_ASSERT( totaloutlen == length );

    TEST_ASSERT( 0 == memcmp(inbuf, decbuf, length) );

exit:
    mbedtls_cipher_free( &ctx_dec );
    mbedtls_cipher_free( &ctx_enc );
}
/* END_CASE */

/* BEGIN_CASE */
void decrypt_test_vec( int cipher_id, int pad_mode, data_t * key,
                       data_t * iv, data_t * cipher,
                       data_t * clear, data_t * ad, data_t * tag,
                       int finish_result, int tag_result )
{
    unsigned char output[265];
    mbedtls_cipher_context_t ctx;
    size_t outlen, total_len;

    mbedtls_cipher_init( &ctx );

    memset( output, 0x00, sizeof( output ) );

#if !defined(MBEDTLS_GCM_C) && !defined(MBEDTLS_CHACHAPOLY_C)
    ((void) ad);
    ((void) tag);
#endif

    /* Prepare context */
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx,
                                       mbedtls_cipher_info_from_type( cipher_id ) ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx, key->x, 8 * key->len, MBEDTLS_DECRYPT ) );
#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    if( pad_mode != -1 )
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx, pad_mode ) );
#else
    (void) pad_mode;
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
    TEST_ASSERT( 0 == mbedtls_cipher_set_iv( &ctx, iv->x, iv->len ) );
    TEST_ASSERT( 0 == mbedtls_cipher_reset( &ctx ) );
#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int expected = ( ctx.cipher_info->mode == MBEDTLS_MODE_GCM ||
                     ctx.cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                   0 : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( expected, mbedtls_cipher_update_ad( &ctx, ad->x, ad->len ) );
#endif

    /* decode buffer and check tag->x */
    total_len = 0;
    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx, cipher->x, cipher->len, output, &outlen ) );
    total_len += outlen;
    TEST_ASSERT( finish_result == mbedtls_cipher_finish( &ctx, output + outlen,
                                                 &outlen ) );
    total_len += outlen;
#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
    int tag_expected = ( ctx.cipher_info->mode == MBEDTLS_MODE_GCM ||
                         ctx.cipher_info->type == MBEDTLS_CIPHER_CHACHA20_POLY1305 ) ?
                       tag_result : MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    TEST_EQUAL( tag_expected, mbedtls_cipher_check_tag( &ctx, tag->x, tag->len ) );
#endif

    /* check plaintext only if everything went fine */
    if( 0 == finish_result && 0 == tag_result )
    {
        TEST_ASSERT( total_len == clear->len );
        TEST_ASSERT( 0 == memcmp( output, clear->x, clear->len ) );
    }

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

/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_AUTH_CRYPT */
void auth_crypt_tv( int cipher_id, data_t * key, data_t * iv,
                    data_t * ad, data_t * cipher, data_t * tag,
                    char * result, data_t * clear, int use_psa )
{
    /*
     * Take an AEAD ciphertext + tag and perform a pair
     * of AEAD decryption and AEAD encryption. Check that
     * this results in the expected plaintext, and that
     * decryption and encryption are inverse to one another.
     */

    int ret;
    int using_nist_kw, using_nist_kw_padding;

    mbedtls_cipher_context_t ctx;
    size_t outlen;

    unsigned char *cipher_plus_tag = NULL;
    size_t cipher_plus_tag_len;
    unsigned char *decrypt_buf = NULL;
    size_t decrypt_buf_len = 0;
    unsigned char *encrypt_buf = NULL;
    size_t encrypt_buf_len = 0;

    /* Null pointers are documented as valid for inputs of length 0.
     * The test framework passes non-null pointers, so set them to NULL.
     * key, cipher and tag can't be empty. */
    if( iv->len == 0 )
        iv->x = NULL;
    if( ad->len == 0 )
        ad->x = NULL;
    if( clear->len == 0 )
        clear->x = NULL;

    mbedtls_cipher_init( &ctx );

    /* Initialize PSA Crypto */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if( use_psa == 1 )
        PSA_ASSERT( psa_crypto_init( ) );
#else
    (void) use_psa;
#endif

    /*
     * Are we using NIST_KW? with padding?
     */
    using_nist_kw_padding = cipher_id == MBEDTLS_CIPHER_AES_128_KWP ||
                            cipher_id == MBEDTLS_CIPHER_AES_192_KWP ||
                            cipher_id == MBEDTLS_CIPHER_AES_256_KWP;
    using_nist_kw = cipher_id == MBEDTLS_CIPHER_AES_128_KW ||
                    cipher_id == MBEDTLS_CIPHER_AES_192_KW ||
                    cipher_id == MBEDTLS_CIPHER_AES_256_KW ||
                    using_nist_kw_padding;

    /*
     * Prepare context for decryption
     */
    if( ! cipher_reset_key( &ctx, cipher_id, use_psa, tag->len, key,
                            MBEDTLS_DECRYPT ) )
        goto exit;

    /*
     * prepare buffer for decryption
     * (we need the tag appended to the ciphertext)
     */
    cipher_plus_tag_len = cipher->len + tag->len;
    ASSERT_ALLOC( cipher_plus_tag, cipher_plus_tag_len );
    memcpy( cipher_plus_tag, cipher->x, cipher->len );
    memcpy( cipher_plus_tag + cipher->len, tag->x, tag->len );

    /*
     * Compute length of output buffer according to the documentation
     */
    if( using_nist_kw )
        decrypt_buf_len = cipher_plus_tag_len - 8;
    else
        decrypt_buf_len = cipher_plus_tag_len - tag->len;


    /*
     * Try decrypting to a buffer that's 1B too small
     */
    if( decrypt_buf_len != 0 )
    {
        ASSERT_ALLOC( decrypt_buf, decrypt_buf_len - 1 );

        outlen = 0;
        ret = mbedtls_cipher_auth_decrypt_ext( &ctx, iv->x, iv->len,
                ad->x, ad->len, cipher_plus_tag, cipher_plus_tag_len,
                decrypt_buf, decrypt_buf_len - 1, &outlen, tag->len );
        TEST_ASSERT( ret == MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );

        mbedtls_free( decrypt_buf );
        decrypt_buf = NULL;
    }

    /*
     * Authenticate and decrypt, and check result
     */
    ASSERT_ALLOC( decrypt_buf, decrypt_buf_len );

    outlen = 0;
    ret = mbedtls_cipher_auth_decrypt_ext( &ctx, iv->x, iv->len,
            ad->x, ad->len, cipher_plus_tag, cipher_plus_tag_len,
            decrypt_buf, decrypt_buf_len, &outlen, tag->len );

    if( strcmp( result, "FAIL" ) == 0 )
    {
        TEST_ASSERT( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED );
        TEST_ASSERT( buffer_is_all_zero( decrypt_buf, decrypt_buf_len ) );
    }
    else
    {
        TEST_ASSERT( ret == 0 );
        ASSERT_COMPARE( decrypt_buf, outlen, clear->x, clear->len );
    }

    mbedtls_free( decrypt_buf );
    decrypt_buf = NULL;

    /*
     * Encrypt back if test data was authentic
     */
    if( strcmp( result, "FAIL" ) != 0 )
    {
        /* prepare context for encryption */
        if( ! cipher_reset_key( &ctx, cipher_id, use_psa, tag->len, key,
                                MBEDTLS_ENCRYPT ) )
            goto exit;

        /*
         * Compute size of output buffer according to documentation
         */
        if( using_nist_kw )
        {
            encrypt_buf_len = clear->len + 8;
            if( using_nist_kw_padding && encrypt_buf_len % 8 != 0 )
                encrypt_buf_len += 8 - encrypt_buf_len % 8;
        }
        else
        {
            encrypt_buf_len = clear->len + tag->len;
        }

        /*
         * Try encrypting with an output buffer that's 1B too small
         */
        ASSERT_ALLOC( encrypt_buf, encrypt_buf_len - 1 );

        outlen = 0;
        ret = mbedtls_cipher_auth_encrypt_ext( &ctx, iv->x, iv->len,
                ad->x, ad->len, clear->x, clear->len,
                encrypt_buf, encrypt_buf_len - 1, &outlen, tag->len );
        TEST_ASSERT( ret != 0 );

        mbedtls_free( encrypt_buf );
        encrypt_buf = NULL;

        /*
         * Encrypt and check the result
         */
        ASSERT_ALLOC( encrypt_buf, encrypt_buf_len );

        outlen = 0;
        ret = mbedtls_cipher_auth_encrypt_ext( &ctx, iv->x, iv->len,
                ad->x, ad->len, clear->x, clear->len,
                encrypt_buf, encrypt_buf_len, &outlen, tag->len );
        TEST_ASSERT( ret == 0 );

        TEST_ASSERT( outlen == cipher->len + tag->len );
        TEST_ASSERT( memcmp( encrypt_buf, cipher->x, cipher->len ) == 0 );
        TEST_ASSERT( memcmp( encrypt_buf + cipher->len,
                             tag->x, tag->len ) == 0 );

        mbedtls_free( encrypt_buf );
        encrypt_buf = NULL;
    }

exit:

    mbedtls_cipher_free( &ctx );
    mbedtls_free( decrypt_buf );
    mbedtls_free( encrypt_buf );
    mbedtls_free( cipher_plus_tag );

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if( use_psa == 1 )
        PSA_DONE( );
#endif /* MBEDTLS_USE_PSA_CRYPTO */
}
/* END_CASE */

/* BEGIN_CASE */
void test_vec_ecb( int cipher_id, int operation, data_t * key,
                   data_t * input, data_t * result, int finish_result
                   )
{
    mbedtls_cipher_context_t ctx;
    unsigned char output[32];
    size_t outlen;

    mbedtls_cipher_init( &ctx );

    memset( output, 0x00, sizeof( output ) );

    /* Prepare context */
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx,
                                       mbedtls_cipher_info_from_type( cipher_id ) ) );


    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx, key->x, 8 * key->len, operation ) );

    TEST_ASSERT( 0 == mbedtls_cipher_update( &ctx, input->x,
                                     mbedtls_cipher_get_block_size( &ctx ),
                                     output, &outlen ) );
    TEST_ASSERT( outlen == mbedtls_cipher_get_block_size( &ctx ) );
    TEST_ASSERT( finish_result == mbedtls_cipher_finish( &ctx, output + outlen,
                                                 &outlen ) );
    TEST_ASSERT( 0 == outlen );

    /* check plaintext only if everything went fine */
    if( 0 == finish_result )
        TEST_ASSERT( 0 == memcmp( output, result->x,
                                  mbedtls_cipher_get_block_size( &ctx ) ) );

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

/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_WITH_PADDING */
void test_vec_crypt( int cipher_id, int operation, data_t *key,
                     data_t *iv, data_t *input, data_t *result,
                     int finish_result, int use_psa )
{
    mbedtls_cipher_context_t ctx;
    unsigned char output[32];
    size_t outlen;

    mbedtls_cipher_init( &ctx );

    memset( output, 0x00, sizeof( output ) );

    /* Prepare context */
#if !defined(MBEDTLS_USE_PSA_CRYPTO) || !defined(MBEDTLS_TEST_DEPRECATED)
    (void) use_psa;
#else
    if( use_psa == 1 )
    {
        PSA_ASSERT( psa_crypto_init( ) );
        TEST_ASSERT( 0 == mbedtls_cipher_setup_psa( &ctx,
                              mbedtls_cipher_info_from_type( cipher_id ), 0 ) );
    }
    else
#endif /* !MBEDTLS_USE_PSA_CRYPTO || !MBEDTLS_TEST_DEPRECATED*/
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx,
                              mbedtls_cipher_info_from_type( cipher_id ) ) );

    TEST_ASSERT( 0 == mbedtls_cipher_setkey( &ctx, key->x, 8 * key->len, operation ) );
    if( MBEDTLS_MODE_CBC == ctx.cipher_info->mode )
        TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx, MBEDTLS_PADDING_NONE ) );

    TEST_ASSERT( finish_result == mbedtls_cipher_crypt( &ctx, iv->len ? iv->x : NULL,
                                                        iv->len, input->x, input->len,
                                                        output, &outlen ) );
    TEST_ASSERT( result->len == outlen );
    /* check plaintext only if everything went fine */
    if( 0 == finish_result )
        TEST_ASSERT( 0 == memcmp( output, result->x, outlen ) );

exit:
    mbedtls_cipher_free( &ctx );
#if defined(MBEDTLS_USE_PSA_CRYPTO) && defined(MBEDTLS_TEST_DEPRECATED)
    PSA_DONE( );
#endif /* MBEDTLS_USE_PSA_CRYPTO && MBEDTLS_TEST_DEPRECATED */
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_WITH_PADDING */
void set_padding( int cipher_id, int pad_mode, int ret )
{
    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_cipher_context_t ctx;

    mbedtls_cipher_init( &ctx );

    cipher_info = mbedtls_cipher_info_from_type( cipher_id );
    TEST_ASSERT( NULL != cipher_info );
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx, cipher_info ) );

    TEST_ASSERT( ret == mbedtls_cipher_set_padding_mode( &ctx, pad_mode ) );

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

/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_CBC */
void check_padding( int pad_mode, data_t * input, int ret, int dlen_check
                    )
{
    mbedtls_cipher_info_t cipher_info;
    mbedtls_cipher_context_t ctx;
    size_t dlen;

    /* build a fake context just for getting access to get_padding */
    mbedtls_cipher_init( &ctx );
    cipher_info.mode = MBEDTLS_MODE_CBC;
    ctx.cipher_info = &cipher_info;

    TEST_ASSERT( 0 == mbedtls_cipher_set_padding_mode( &ctx, pad_mode ) );


    TEST_ASSERT( ret == ctx.get_padding( input->x, input->len, &dlen ) );
    if( 0 == ret )
        TEST_ASSERT( dlen == (size_t) dlen_check );
}
/* END_CASE */

/* BEGIN_CASE */
void iv_len_validity( int cipher_id, char * cipher_string,
               int iv_len_val, int ret )
{
    size_t iv_len = iv_len_val;
    unsigned char iv[16];

    /* Initialise iv buffer */
    memset( iv, 0, sizeof( iv ) );

    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_cipher_context_t ctx_dec;
    mbedtls_cipher_context_t ctx_enc;

    /*
     * Prepare contexts
     */
    mbedtls_cipher_init( &ctx_dec );
    mbedtls_cipher_init( &ctx_enc );

    /* Check and get info structures */
    cipher_info = mbedtls_cipher_info_from_type( cipher_id );
    TEST_ASSERT( NULL != cipher_info );
    TEST_ASSERT( mbedtls_cipher_info_from_string( cipher_string ) == cipher_info );
    TEST_ASSERT( strcmp( mbedtls_cipher_info_get_name( cipher_info ),
                         cipher_string ) == 0 );

    /* Initialise enc and dec contexts */
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_dec, cipher_info ) );
    TEST_ASSERT( 0 == mbedtls_cipher_setup( &ctx_enc, cipher_info ) );

    TEST_ASSERT( ret == mbedtls_cipher_set_iv( &ctx_dec, iv, iv_len ) );
    TEST_ASSERT( ret == mbedtls_cipher_set_iv( &ctx_enc, iv, iv_len ) );

exit:
    mbedtls_cipher_free( &ctx_dec );
    mbedtls_cipher_free( &ctx_enc );
}
/* END_CASE */