tests/suites/test_suite_ecdsa.function

/* BEGIN_HEADER */
#include "mbedtls/ecdsa.h"
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_ECDSA_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE depends_on:MBEDTLS_CHECK_PARAMS:!MBEDTLS_PARAM_FAILED_ALT */
void ecdsa_invalid_param( )
{
    mbedtls_ecdsa_context ctx;
    mbedtls_ecp_keypair key;
    mbedtls_ecp_group grp;
    mbedtls_ecp_group_id valid_group = MBEDTLS_ECP_DP_SECP192R1;
    mbedtls_ecp_point P;
    mbedtls_md_type_t valid_md = MBEDTLS_MD_SHA256;
    mbedtls_mpi m;
    size_t slen;
    unsigned char buf[42] = { 0 };

    TEST_INVALID_PARAM( mbedtls_ecdsa_init( NULL ) );
    TEST_VALID_PARAM( mbedtls_ecdsa_free( NULL ) );

#if defined(MBEDTLS_ECP_RESTARTABLE)
    TEST_INVALID_PARAM( mbedtls_ecdsa_restart_init( NULL ) );
    TEST_VALID_PARAM( mbedtls_ecdsa_restart_free( NULL ) );
#endif /* MBEDTLS_ECP_RESTARTABLE */

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                            mbedtls_ecdsa_sign( NULL, &m, &m, &m,
                                                buf, sizeof( buf ),
                                                mbedtls_test_rnd_std_rand,
                                                NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                            mbedtls_ecdsa_sign( &grp, NULL, &m, &m,
                                                buf, sizeof( buf ),
                                                mbedtls_test_rnd_std_rand,
                                                NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign( &grp, &m, NULL, &m,
                                                buf, sizeof( buf ),
                                                mbedtls_test_rnd_std_rand,
                                                NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign( &grp, &m, &m, NULL,
                                                buf, sizeof( buf ),
                                                mbedtls_test_rnd_std_rand,
                                                NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign( &grp, &m, &m, &m,
                                                NULL, sizeof( buf ),
                                                mbedtls_test_rnd_std_rand,
                                                NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign( &grp, &m, &m, &m,
                                                buf, sizeof( buf ),
                                                NULL, NULL ) );

#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign_det_ext( NULL, &m, &m, &m,
                                                   buf, sizeof( buf ),
                                                   valid_md,
                                                   mbedtls_test_rnd_std_rand,
                                                   NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign_det_ext( &grp, NULL, &m, &m,
                                                   buf, sizeof( buf ),
                                                   valid_md,
                                                   mbedtls_test_rnd_std_rand,
                                                   NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign_det_ext( &grp, &m, NULL, &m,
                                                   buf, sizeof( buf ),
                                                   valid_md,
                                                   mbedtls_test_rnd_std_rand,
                                                   NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign_det_ext( &grp, &m, &m, NULL,
                                                   buf, sizeof( buf ),
                                                   valid_md,
                                                   mbedtls_test_rnd_std_rand,
                                                   NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_sign_det_ext( &grp, &m, &m, &m,
                                                   NULL, sizeof( buf ),
                                                   valid_md,
                                                   mbedtls_test_rnd_std_rand,
                                                   NULL ) );
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_verify( NULL,
                                                  buf, sizeof( buf ),
                                                  &P, &m, &m ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_verify( &grp,
                                                  NULL, sizeof( buf ),
                                                  &P, &m, &m ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_verify( &grp,
                                                  buf, sizeof( buf ),
                                                  NULL, &m, &m ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_verify( &grp,
                                                  buf, sizeof( buf ),
                                                  &P, NULL, &m ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_verify( &grp,
                                                  buf, sizeof( buf ),
                                                  &P, &m, NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature( NULL, valid_md, buf, sizeof( buf ),
                                        buf, &slen, mbedtls_test_rnd_std_rand,
                                        NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature( &ctx, valid_md, NULL, sizeof( buf ),
                                        buf, &slen, mbedtls_test_rnd_std_rand,
                                        NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature( &ctx, valid_md, buf, sizeof( buf ),
                                        NULL, &slen, mbedtls_test_rnd_std_rand,
                                        NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature( &ctx, valid_md, buf, sizeof( buf ),
                                        buf, NULL, mbedtls_test_rnd_std_rand,
                                        NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature_restartable( NULL, valid_md, buf,
                                                    sizeof( buf ), buf, &slen,
                                                    mbedtls_test_rnd_std_rand,
                                                    NULL, NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature_restartable( &ctx, valid_md, NULL,
                                                    sizeof( buf ), buf, &slen,
                                                    mbedtls_test_rnd_std_rand,
                                                    NULL, NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature_restartable( &ctx, valid_md, buf,
                                                    sizeof( buf ), NULL, &slen,
                                                    mbedtls_test_rnd_std_rand,
                                                    NULL, NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
         mbedtls_ecdsa_write_signature_restartable( &ctx, valid_md, buf,
                                                    sizeof( buf ), buf, NULL,
                                                    mbedtls_test_rnd_std_rand,
                                                    NULL, NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature( NULL,
                                                        buf, sizeof( buf ),
                                                        buf, sizeof( buf ) ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature( &ctx,
                                                        NULL, sizeof( buf ),
                                                        buf, sizeof( buf ) ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature( &ctx,
                                                        buf, sizeof( buf ),
                                                        NULL, sizeof( buf ) ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature_restartable( NULL,
                                                        buf, sizeof( buf ),
                                                        buf, sizeof( buf ),
                                                        NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature_restartable( &ctx,
                                                        NULL, sizeof( buf ),
                                                        buf, sizeof( buf ),
                                                        NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_read_signature_restartable( &ctx,
                                                        buf, sizeof( buf ),
                                                        NULL, sizeof( buf ),
                                                        NULL ) );

    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_genkey( NULL, valid_group,
                                             mbedtls_test_rnd_std_rand,
                                             NULL ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_genkey( &ctx, valid_group,
                                                  NULL, NULL ) );


    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_from_keypair( NULL, &key ) );
    TEST_INVALID_PARAM_RET( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
                       mbedtls_ecdsa_from_keypair( &ctx, NULL ) );

exit:
    return;
}
/* END_CASE */

/* BEGIN_CASE */
void ecdsa_prim_random( int id )
{
    mbedtls_ecp_group grp;
    mbedtls_ecp_point Q;
    mbedtls_mpi d, r, s;
    mbedtls_test_rnd_pseudo_info rnd_info;
    unsigned char buf[MBEDTLS_MD_MAX_SIZE];
    int test_runs = 2;

    mbedtls_ecp_group_init( &grp );
    mbedtls_ecp_point_init( &Q );
    mbedtls_mpi_init( &d ); mbedtls_mpi_init( &r ); mbedtls_mpi_init( &s );
    memset( &rnd_info, 0x00, sizeof( mbedtls_test_rnd_pseudo_info ) );
    memset( buf, 0, sizeof( buf ) );

    while ( test_runs-- )
    {
        /* prepare material for signature */
        if ( test_runs == 1 )
        {
            TEST_ASSERT( mbedtls_test_rnd_pseudo_rand( &rnd_info,
                                                       buf, sizeof( buf ) ) 
                                                     == 0 );
        } else {
            TEST_ASSERT( mbedtls_test_rnd_zero_rand( NULL,
                                                     buf, sizeof( buf ) ) 
                                                   == 0 );
        }

        TEST_ASSERT( mbedtls_ecp_group_load( &grp, id ) == 0 );
        TEST_ASSERT( mbedtls_ecp_gen_keypair( &grp, &d, &Q,
                                              &mbedtls_test_rnd_pseudo_rand,
                                              &rnd_info ) == 0 );

        TEST_ASSERT( mbedtls_ecdsa_sign( &grp, &r, &s, &d, buf, sizeof( buf ),
                                         &mbedtls_test_rnd_pseudo_rand,
                                         &rnd_info ) == 0 );
        TEST_ASSERT( mbedtls_ecdsa_verify( &grp, buf, sizeof( buf ), &Q, &r, &s ) 
                                         == 0 );
    }

exit:
    mbedtls_ecp_group_free( &grp );
    mbedtls_ecp_point_free( &Q );
    mbedtls_mpi_free( &d ); mbedtls_mpi_free( &r ); mbedtls_mpi_free( &s );
}
/* END_CASE */

/* BEGIN_CASE */
void ecdsa_prim_test_vectors( int id, char * d_str, char * xQ_str,
                              char * yQ_str, data_t * rnd_buf,
                              data_t * hash, char * r_str, char * s_str,
                              int result )
{
    mbedtls_ecp_group grp;
    mbedtls_ecp_point Q;
    mbedtls_mpi d, r, s, r_check, s_check;
    mbedtls_test_rnd_buf_info rnd_info;

    mbedtls_ecp_group_init( &grp );
    mbedtls_ecp_point_init( &Q );
    mbedtls_mpi_init( &d ); mbedtls_mpi_init( &r ); mbedtls_mpi_init( &s );
    mbedtls_mpi_init( &r_check ); mbedtls_mpi_init( &s_check );

    TEST_ASSERT( mbedtls_ecp_group_load( &grp, id ) == 0 );
    TEST_ASSERT( mbedtls_ecp_point_read_string( &Q, 16, xQ_str, yQ_str ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &d, 16, d_str ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &r_check, 16, r_str ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &s_check, 16, s_str ) == 0 );
    rnd_info.buf = rnd_buf->x;
    rnd_info.length = rnd_buf->len;

    /* Fix rnd_buf->x by shifting it left if necessary */
    if( grp.nbits % 8 != 0 )
    {
        unsigned char shift = 8 - ( grp.nbits % 8 );
        size_t i;

        for( i = 0; i < rnd_info.length - 1; i++ )
            rnd_buf->x[i] = rnd_buf->x[i] << shift | rnd_buf->x[i+1] >> ( 8 - shift );

        rnd_buf->x[rnd_info.length-1] <<= shift;
    }

    TEST_ASSERT( mbedtls_ecdsa_sign( &grp, &r, &s, &d, hash->x, hash->len,
                 mbedtls_test_rnd_buffer_rand, &rnd_info ) == result );

    if ( result == 0)
    {
        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &r, &r_check ) == 0 );
        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &s, &s_check ) == 0 );

        TEST_ASSERT( mbedtls_ecdsa_verify( &grp, hash->x, hash->len, &Q, &r_check, &s_check ) == 0 );

        TEST_ASSERT( mbedtls_mpi_sub_int( &r, &r, 1 ) == 0 );
        TEST_ASSERT( mbedtls_mpi_add_int( &s, &s, 1 ) == 0 );

        TEST_ASSERT( mbedtls_ecdsa_verify( &grp, hash->x, hash->len,
                     &Q, &r, &s_check ) == MBEDTLS_ERR_ECP_VERIFY_FAILED );
        TEST_ASSERT( mbedtls_ecdsa_verify( &grp, hash->x, hash->len,
                     &Q, &r_check, &s ) == MBEDTLS_ERR_ECP_VERIFY_FAILED );
        TEST_ASSERT( mbedtls_ecdsa_verify( &grp, hash->x, hash->len,
                     &grp.G, &r_check, &s_check ) == MBEDTLS_ERR_ECP_VERIFY_FAILED );
    }

exit:
    mbedtls_ecp_group_free( &grp );
    mbedtls_ecp_point_free( &Q );
    mbedtls_mpi_free( &d ); mbedtls_mpi_free( &r ); mbedtls_mpi_free( &s );
    mbedtls_mpi_free( &r_check ); mbedtls_mpi_free( &s_check );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ECDSA_DETERMINISTIC */
void ecdsa_det_test_vectors( int id, char * d_str, int md_alg, char * msg,
                             char * r_str, char * s_str )
{
    mbedtls_ecp_group grp;
    mbedtls_mpi d, r, s, r_check, s_check;
    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
    size_t hlen;
    const mbedtls_md_info_t *md_info;

    mbedtls_ecp_group_init( &grp );
    mbedtls_mpi_init( &d ); mbedtls_mpi_init( &r ); mbedtls_mpi_init( &s );
    mbedtls_mpi_init( &r_check ); mbedtls_mpi_init( &s_check );
    memset( hash, 0, sizeof( hash ) );

    TEST_ASSERT( mbedtls_ecp_group_load( &grp, id ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &d, 16, d_str ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &r_check, 16, r_str ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &s_check, 16, s_str ) == 0 );

    md_info = mbedtls_md_info_from_type( md_alg );
    TEST_ASSERT( md_info != NULL );
    hlen = mbedtls_md_get_size( md_info );
    TEST_ASSERT( mbedtls_md( md_info, (const unsigned char *) msg,
                 strlen( msg ), hash ) == 0 );

    TEST_ASSERT(
                mbedtls_ecdsa_sign_det_ext( &grp, &r, &s, &d, hash, hlen,
                                            md_alg, mbedtls_test_rnd_std_rand,
                                            NULL )
                == 0 );

    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &r, &r_check ) == 0 );
    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &s, &s_check ) == 0 );

exit:
    mbedtls_ecp_group_free( &grp );
    mbedtls_mpi_free( &d ); mbedtls_mpi_free( &r ); mbedtls_mpi_free( &s );
    mbedtls_mpi_free( &r_check ); mbedtls_mpi_free( &s_check );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SHA256_C */
void ecdsa_write_read_random( int id )
{
    mbedtls_ecdsa_context ctx;
    mbedtls_test_rnd_pseudo_info rnd_info;
    unsigned char hash[32];
    unsigned char sig[200];
    size_t sig_len, i;
    int test_runs = 2;

    mbedtls_ecdsa_init( &ctx );
    memset( &rnd_info, 0x00, sizeof( mbedtls_test_rnd_pseudo_info ) );
    memset( hash, 0, sizeof( hash ) );

    while ( test_runs-- )
    {
        memset( sig, 0x2a, sizeof( sig ) );

        /* prepare material for signature */
        if ( test_runs == 1 )
        {
            TEST_ASSERT( mbedtls_test_rnd_pseudo_rand( &rnd_info,
                                                       hash, sizeof( hash ) ) 
                                                     == 0 );
        } else {
            TEST_ASSERT( mbedtls_test_rnd_zero_rand( NULL,
                                                       hash, sizeof( hash ) ) 
                                                    == 0 );
        }

        /* generate signing key */
        TEST_ASSERT( mbedtls_ecdsa_genkey( &ctx, id,
                                           &mbedtls_test_rnd_pseudo_rand,
                                           &rnd_info ) == 0 );

        /* generate and write signature, then read and verify it */
        TEST_ASSERT( mbedtls_ecdsa_write_signature( &ctx, MBEDTLS_MD_SHA256,
                     hash, sizeof( hash ),
                     sig, &sig_len, &mbedtls_test_rnd_pseudo_rand,
                     &rnd_info ) == 0 );

        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len ) == 0 );

        /* check we didn't write past the announced length */
        for( i = sig_len; i < sizeof( sig ); i++ )
            TEST_ASSERT( sig[i] == 0x2a );

        /* try verification with invalid length */
        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len - 1 ) != 0 );
        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len + 1 ) != 0 );

        /* try invalid sequence tag */
        sig[0]++;
        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len ) != 0 );
        sig[0]--;

        /* try modifying r */
        sig[10]++;
        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len ) == MBEDTLS_ERR_ECP_VERIFY_FAILED );
        sig[10]--;

        /* try modifying s */
        sig[sig_len - 1]++;
        TEST_ASSERT( mbedtls_ecdsa_read_signature( &ctx, hash, sizeof( hash ),
                     sig, sig_len ) == MBEDTLS_ERR_ECP_VERIFY_FAILED );
        sig[sig_len - 1]--;
    }

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

/* BEGIN_CASE depends_on:MBEDTLS_ECP_RESTARTABLE */
void ecdsa_read_restart( int id, data_t *pk, data_t *hash, data_t *sig,
                         int max_ops, int min_restart, int max_restart )
{
    mbedtls_ecdsa_context ctx;
    mbedtls_ecdsa_restart_ctx rs_ctx;
    int ret, cnt_restart;

    mbedtls_ecdsa_init( &ctx );
    mbedtls_ecdsa_restart_init( &rs_ctx );

    TEST_ASSERT( mbedtls_ecp_group_load( &ctx.grp, id ) == 0 );
    TEST_ASSERT( mbedtls_ecp_point_read_binary( &ctx.grp, &ctx.Q,
                                                pk->x, pk->len ) == 0 );

    mbedtls_ecp_set_max_ops( max_ops );

    cnt_restart = 0;
    do {
        ret = mbedtls_ecdsa_read_signature_restartable( &ctx,
                            hash->x, hash->len, sig->x, sig->len, &rs_ctx );
    } while( ret == MBEDTLS_ERR_ECP_IN_PROGRESS && ++cnt_restart );

    TEST_ASSERT( ret == 0 );
    TEST_ASSERT( cnt_restart >= min_restart );
    TEST_ASSERT( cnt_restart <= max_restart );

    /* try modifying r */

    TEST_ASSERT( sig->len > 10 );
    sig->x[10]++;
    do {
        ret = mbedtls_ecdsa_read_signature_restartable( &ctx,
                            hash->x, hash->len, sig->x, sig->len, &rs_ctx );
    } while( ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
    TEST_ASSERT( ret == MBEDTLS_ERR_ECP_VERIFY_FAILED );
    sig->x[10]--;

    /* try modifying s */
    sig->x[sig->len - 1]++;
    do {
        ret = mbedtls_ecdsa_read_signature_restartable( &ctx,
                            hash->x, hash->len, sig->x, sig->len, &rs_ctx );
    } while( ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
    TEST_ASSERT( ret == MBEDTLS_ERR_ECP_VERIFY_FAILED );
    sig->x[sig->len - 1]--;

    /* Do we leak memory when aborting an operation?
     * This test only makes sense when we actually restart */
    if( min_restart > 0 )
    {
        ret = mbedtls_ecdsa_read_signature_restartable( &ctx,
                            hash->x, hash->len, sig->x, sig->len, &rs_ctx );
        TEST_ASSERT( ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
    }

exit:
    mbedtls_ecdsa_free( &ctx );
    mbedtls_ecdsa_restart_free( &rs_ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_ECP_RESTARTABLE:MBEDTLS_ECDSA_DETERMINISTIC */
void ecdsa_write_restart( int id, char *d_str, int md_alg,
                          char *msg, data_t *sig_check,
                          int max_ops, int min_restart, int max_restart )
{
    int ret, cnt_restart;
    mbedtls_ecdsa_restart_ctx rs_ctx;
    mbedtls_ecdsa_context ctx;
    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
    unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
    size_t hlen, slen;
    const mbedtls_md_info_t *md_info;

    mbedtls_ecdsa_restart_init( &rs_ctx );
    mbedtls_ecdsa_init( &ctx );
    memset( hash, 0, sizeof( hash ) );
    memset( sig, 0, sizeof( sig ) );

    TEST_ASSERT( mbedtls_ecp_group_load( &ctx.grp, id ) == 0 );
    TEST_ASSERT( mbedtls_mpi_read_string( &ctx.d, 16, d_str ) == 0 );

    md_info = mbedtls_md_info_from_type( md_alg );
    TEST_ASSERT( md_info != NULL );

    hlen = mbedtls_md_get_size( md_info );
    TEST_ASSERT( mbedtls_md( md_info,
                             (const unsigned char *) msg, strlen( msg ),
                             hash ) == 0 );

    mbedtls_ecp_set_max_ops( max_ops );

    slen = sizeof( sig );
    cnt_restart = 0;
    do {
        ret = mbedtls_ecdsa_write_signature_restartable( &ctx,
                md_alg, hash, hlen, sig, &slen, NULL, NULL, &rs_ctx );
    } while( ret == MBEDTLS_ERR_ECP_IN_PROGRESS && ++cnt_restart );

    TEST_ASSERT( ret == 0 );
    TEST_ASSERT( slen == sig_check->len );
    TEST_ASSERT( memcmp( sig, sig_check->x, slen ) == 0 );

    TEST_ASSERT( cnt_restart >= min_restart );
    TEST_ASSERT( cnt_restart <= max_restart );

    /* Do we leak memory when aborting an operation?
     * This test only makes sense when we actually restart */
    if( min_restart > 0 )
    {
        ret = mbedtls_ecdsa_write_signature_restartable( &ctx,
                md_alg, hash, hlen, sig, &slen, NULL, NULL, &rs_ctx );
        TEST_ASSERT( ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
    }

exit:
    mbedtls_ecdsa_restart_free( &rs_ctx );
    mbedtls_ecdsa_free( &ctx );
}
/* END_CASE */