tests/suites/test_suite_x509write.function

/* BEGIN_HEADER */
#include "mbedtls/bignum.h"
#include "mbedtls/x509_crt.h"
#include "mbedtls/x509_csr.h"
#include "mbedtls/pem.h"
#include "mbedtls/oid.h"
#include "mbedtls/rsa.h"
#include "mbedtls/asn1write.h"

#include "hash_info.h"
#include "mbedtls/legacy_or_psa.h"

#if defined(MBEDTLS_RSA_C)
int mbedtls_rsa_decrypt_func(void *ctx, size_t *olen,
                             const unsigned char *input, unsigned char *output,
                             size_t output_max_len)
{
    return mbedtls_rsa_pkcs1_decrypt((mbedtls_rsa_context *) ctx, NULL, NULL,
                                     olen, input, output, output_max_len);
}
int mbedtls_rsa_sign_func(void *ctx,
                          int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
                          mbedtls_md_type_t md_alg, unsigned int hashlen,
                          const unsigned char *hash, unsigned char *sig)
{
    return mbedtls_rsa_pkcs1_sign((mbedtls_rsa_context *) ctx, f_rng, p_rng,
                                  md_alg, hashlen, hash, sig);
}
size_t mbedtls_rsa_key_len_func(void *ctx)
{
    return ((const mbedtls_rsa_context *) ctx)->len;
}
#endif /* MBEDTLS_RSA_C */

#if defined(MBEDTLS_USE_PSA_CRYPTO) && \
    defined(MBEDTLS_PEM_WRITE_C) && defined(MBEDTLS_X509_CSR_WRITE_C)
static int x509_crt_verifycsr(const unsigned char *buf, size_t buflen)
{
    unsigned char hash[PSA_HASH_MAX_SIZE];
    mbedtls_x509_csr csr;
    int ret = 0;

    mbedtls_x509_csr_init(&csr);

    if (mbedtls_x509_csr_parse(&csr, buf, buflen) != 0) {
        ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
        goto cleanup;
    }

    psa_algorithm_t psa_alg = mbedtls_hash_info_psa_from_md(csr.sig_md);
    size_t hash_size = 0;
    psa_status_t status = psa_hash_compute(psa_alg, csr.cri.p, csr.cri.len,
                                           hash, PSA_HASH_MAX_SIZE, &hash_size);

    if (status != PSA_SUCCESS) {
        /* Note: this can't happen except after an internal error */
        ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
        goto cleanup;
    }

    if (mbedtls_pk_verify_ext(csr.sig_pk, csr.sig_opts, &csr.pk,
                              csr.sig_md, hash, mbedtls_hash_info_get_size(csr.sig_md),
                              csr.sig.p, csr.sig.len) != 0) {
        ret = MBEDTLS_ERR_X509_CERT_VERIFY_FAILED;
        goto cleanup;
    }

cleanup:

    mbedtls_x509_csr_free(&csr);
    return ret;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO && MBEDTLS_PEM_WRITE_C && MBEDTLS_X509_CSR_WRITE_C */

#if defined(MBEDTLS_X509_CSR_WRITE_C)

/*
 * The size of this temporary buffer is given by the sequence of functions
 * called hereinafter:
 * - mbedtls_asn1_write_oid()
 *     - 8 bytes for MBEDTLS_OID_EXTENDED_KEY_USAGE raw value
 *     - 1 byte for MBEDTLS_OID_EXTENDED_KEY_USAGE length
 *     - 1 byte for MBEDTLS_ASN1_OID tag
 * - mbedtls_asn1_write_len()
 *     - 1 byte since we're dealing with sizes which are less than 0x80
 * - mbedtls_asn1_write_tag()
 *     - 1 byte
 *
 * This length is fine as long as this function is called using the
 * MBEDTLS_OID_SERVER_AUTH OID. If this is changed in the future, then this
 * buffer's length should be adjusted accordingly.
 * Unfortunately there's no predefined max size for OIDs which can be used
 * to set an overall upper boundary which is always guaranteed.
 */
#define EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH    12

static int csr_set_extended_key_usage(mbedtls_x509write_csr *ctx,
                                      const char *oid, size_t oid_len)
{
    unsigned char buf[EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH] = { 0 };
    unsigned char *p = buf + sizeof(buf);
    int ret;
    size_t len = 0;

    /*
     * Following functions fail anyway if the temporary buffer is not large,
     * but we set an extra check here to emphasize a possible source of errors
     */
    if (oid_len > EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH) {
        return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
    }

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(&p, buf, oid, oid_len));
    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&p, buf, ret));
    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&p, buf,
                                                     MBEDTLS_ASN1_CONSTRUCTED |
                                                     MBEDTLS_ASN1_SEQUENCE));

    ret = mbedtls_x509write_csr_set_extension(ctx,
                                              MBEDTLS_OID_EXTENDED_KEY_USAGE,
                                              MBEDTLS_OID_SIZE(MBEDTLS_OID_EXTENDED_KEY_USAGE),
                                              0,
                                              p,
                                              len);

    return ret;
}
#endif  /* MBEDTLS_X509_CSR_WRITE_C */
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_BIGNUM_C:MBEDTLS_FS_IO:MBEDTLS_PK_PARSE_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CSR_WRITE_C */
void x509_csr_check(char *key_file, char *cert_req_check_file, int md_type,
                    int key_usage, int set_key_usage, int cert_type,
                    int set_cert_type, int set_extension)
{
    mbedtls_pk_context key;
    mbedtls_x509write_csr req;
    unsigned char buf[4096];
    int ret;
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
    unsigned char check_buf[4000];
    FILE *f;
    size_t olen = 0;
#endif /* !MBEDTLS_USE_PSA_CRYPTO */
    size_t pem_len = 0, buf_index;
    int der_len = -1;
    const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
    mbedtls_test_rnd_pseudo_info rnd_info;

    memset(&rnd_info, 0x2a, sizeof(mbedtls_test_rnd_pseudo_info));

    mbedtls_x509write_csr_init(&req);

    USE_PSA_INIT();

    mbedtls_pk_init(&key);
    TEST_ASSERT(mbedtls_pk_parse_keyfile(&key, key_file, NULL,
                                         mbedtls_test_rnd_std_rand, NULL) == 0);

    mbedtls_x509write_csr_set_md_alg(&req, md_type);
    mbedtls_x509write_csr_set_key(&req, &key);
    TEST_ASSERT(mbedtls_x509write_csr_set_subject_name(&req, subject_name) == 0);
    if (set_key_usage != 0) {
        TEST_ASSERT(mbedtls_x509write_csr_set_key_usage(&req, key_usage) == 0);
    }
    if (set_cert_type != 0) {
        TEST_ASSERT(mbedtls_x509write_csr_set_ns_cert_type(&req, cert_type) == 0);
    }
    if (set_extension != 0) {
        TEST_ASSERT(csr_set_extended_key_usage(&req, MBEDTLS_OID_SERVER_AUTH,
                                               MBEDTLS_OID_SIZE(MBEDTLS_OID_SERVER_AUTH)) == 0);
    }

    ret = mbedtls_x509write_csr_pem(&req, buf, sizeof(buf),
                                    mbedtls_test_rnd_pseudo_rand, &rnd_info);
    TEST_ASSERT(ret == 0);

    pem_len = strlen((char *) buf);

    for (buf_index = pem_len; buf_index < sizeof(buf); ++buf_index) {
        TEST_ASSERT(buf[buf_index] == 0);
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, so cert_req_check_file can't be used
    (void) cert_req_check_file;
    buf[pem_len] = '\0';
    TEST_ASSERT(x509_crt_verifycsr(buf, pem_len + 1) == 0);
#else
    f = fopen(cert_req_check_file, "r");
    TEST_ASSERT(f != NULL);
    olen = fread(check_buf, 1, sizeof(check_buf), f);
    fclose(f);

    TEST_ASSERT(olen >= pem_len - 1);
    TEST_ASSERT(memcmp(buf, check_buf, pem_len - 1) == 0);
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    der_len = mbedtls_x509write_csr_der(&req, buf, sizeof(buf),
                                        mbedtls_test_rnd_pseudo_rand,
                                        &rnd_info);
    TEST_ASSERT(der_len >= 0);

    if (der_len == 0) {
        goto exit;
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, result length isn't
    // deterministic over multiple runs, removing a single byte isn't enough to
    // go into the MBEDTLS_ERR_ASN1_BUF_TOO_SMALL error case
    der_len /= 2;
#else
    der_len -= 1;
#endif
    ret = mbedtls_x509write_csr_der(&req, buf, (size_t) (der_len),
                                    mbedtls_test_rnd_pseudo_rand, &rnd_info);
    TEST_ASSERT(ret == MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);

exit:
    mbedtls_x509write_csr_free(&req);
    mbedtls_pk_free(&key);
    USE_PSA_DONE();
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CSR_WRITE_C:MBEDTLS_USE_PSA_CRYPTO */
void x509_csr_check_opaque(char *key_file, int md_type, int key_usage,
                           int cert_type)
{
    mbedtls_pk_context key;
    mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
    psa_algorithm_t md_alg_psa, alg_psa;
    mbedtls_x509write_csr req;
    unsigned char buf[4096];
    int ret;
    size_t pem_len = 0;
    const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
    mbedtls_test_rnd_pseudo_info rnd_info;

    memset(&rnd_info, 0x2a, sizeof(mbedtls_test_rnd_pseudo_info));

    mbedtls_x509write_csr_init(&req);

    USE_PSA_INIT();

    md_alg_psa = mbedtls_hash_info_psa_from_md((mbedtls_md_type_t) md_type);
    TEST_ASSERT(md_alg_psa != MBEDTLS_MD_NONE);

    mbedtls_pk_init(&key);
    TEST_ASSERT(mbedtls_pk_parse_keyfile(&key, key_file, NULL,
                                         mbedtls_test_rnd_std_rand, NULL) == 0);

    if (mbedtls_pk_get_type(&key) == MBEDTLS_PK_ECKEY) {
        alg_psa = PSA_ALG_ECDSA(md_alg_psa);
    } else if (mbedtls_pk_get_type(&key) == MBEDTLS_PK_RSA) {
        alg_psa = PSA_ALG_RSA_PKCS1V15_SIGN(md_alg_psa);
    } else {
        TEST_ASSUME(!"PK key type not supported in this configuration");
    }

    TEST_ASSERT(mbedtls_pk_wrap_as_opaque(&key, &key_id, alg_psa,
                                          PSA_KEY_USAGE_SIGN_HASH,
                                          PSA_ALG_NONE) == 0);

    mbedtls_x509write_csr_set_md_alg(&req, md_type);
    mbedtls_x509write_csr_set_key(&req, &key);
    TEST_ASSERT(mbedtls_x509write_csr_set_subject_name(&req, subject_name) == 0);
    if (key_usage != 0) {
        TEST_ASSERT(mbedtls_x509write_csr_set_key_usage(&req, key_usage) == 0);
    }
    if (cert_type != 0) {
        TEST_ASSERT(mbedtls_x509write_csr_set_ns_cert_type(&req, cert_type) == 0);
    }

    ret = mbedtls_x509write_csr_pem(&req, buf, sizeof(buf) - 1,
                                    mbedtls_test_rnd_pseudo_rand, &rnd_info);

    TEST_ASSERT(ret == 0);

    pem_len = strlen((char *) buf);
    buf[pem_len] = '\0';
    TEST_ASSERT(x509_crt_verifycsr(buf, pem_len + 1) == 0);


exit:
    mbedtls_x509write_csr_free(&req);
    mbedtls_pk_free(&key);
    psa_destroy_key(key_id);
    PSA_DONE();
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CRT_WRITE_C:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA_BASED_ON_USE_PSA */
void x509_crt_check(char *subject_key_file, char *subject_pwd,
                    char *subject_name, char *issuer_key_file,
                    char *issuer_pwd, char *issuer_name,
                    data_t *serial_arg, char *not_before, char *not_after,
                    int md_type, int key_usage, int set_key_usage,
                    char *ext_key_usage,
                    int cert_type, int set_cert_type, int auth_ident,
                    int ver, char *cert_check_file, int pk_wrap, int is_ca,
                    char *cert_verify_file)
{
    mbedtls_pk_context subject_key, issuer_key, issuer_key_alt;
    mbedtls_pk_context *key = &issuer_key;

    mbedtls_x509write_cert crt;
    unsigned char buf[4096];
    unsigned char check_buf[5000];
    unsigned char *p, *end;
    unsigned char tag, sz;
#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    mbedtls_mpi serial_mpi;
#endif
    int ret, before_tag, after_tag;
    size_t olen = 0, pem_len = 0, buf_index = 0;
    int der_len = -1;
    FILE *f;
    mbedtls_test_rnd_pseudo_info rnd_info;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
#endif
    mbedtls_pk_type_t issuer_key_type;

    memset(&rnd_info, 0x2a, sizeof(mbedtls_test_rnd_pseudo_info));
#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    mbedtls_mpi_init(&serial_mpi);
#endif

    USE_PSA_INIT();

    mbedtls_pk_init(&subject_key);
    mbedtls_pk_init(&issuer_key);
    mbedtls_pk_init(&issuer_key_alt);

    mbedtls_x509write_crt_init(&crt);

    TEST_ASSERT(mbedtls_pk_parse_keyfile(&subject_key, subject_key_file,
                                         subject_pwd, mbedtls_test_rnd_std_rand, NULL) == 0);

    TEST_ASSERT(mbedtls_pk_parse_keyfile(&issuer_key, issuer_key_file,
                                         issuer_pwd, mbedtls_test_rnd_std_rand, NULL) == 0);

    issuer_key_type = mbedtls_pk_get_type(&issuer_key);

#if defined(MBEDTLS_RSA_C)
    /* For RSA PK contexts, create a copy as an alternative RSA context. */
    if (pk_wrap == 1 && issuer_key_type == MBEDTLS_PK_RSA) {
        TEST_ASSERT(mbedtls_pk_setup_rsa_alt(&issuer_key_alt,
                                             mbedtls_pk_rsa(issuer_key),
                                             mbedtls_rsa_decrypt_func,
                                             mbedtls_rsa_sign_func,
                                             mbedtls_rsa_key_len_func) == 0);

        key = &issuer_key_alt;
    }
#endif

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    /* For Opaque PK contexts, wrap key as an Opaque RSA context. */
    if (pk_wrap == 2) {
        psa_algorithm_t alg_psa, md_alg_psa;

        md_alg_psa = mbedtls_hash_info_psa_from_md((mbedtls_md_type_t) md_type);
        TEST_ASSERT(md_alg_psa != MBEDTLS_MD_NONE);

        if (mbedtls_pk_get_type(&issuer_key) == MBEDTLS_PK_ECKEY) {
            alg_psa = PSA_ALG_ECDSA(md_alg_psa);
        } else if (mbedtls_pk_get_type(&issuer_key) == MBEDTLS_PK_RSA) {
            alg_psa = PSA_ALG_RSA_PKCS1V15_SIGN(md_alg_psa);
        } else {
            TEST_ASSUME(!"PK key type not supported in this configuration");
        }

        TEST_ASSERT(mbedtls_pk_wrap_as_opaque(&issuer_key, &key_id, alg_psa,
                                              PSA_KEY_USAGE_SIGN_HASH,
                                              PSA_ALG_NONE) == 0);
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    if (pk_wrap == 2) {
        TEST_ASSERT(mbedtls_pk_get_type(&issuer_key) == MBEDTLS_PK_OPAQUE);
    }

    if (ver != -1) {
        mbedtls_x509write_crt_set_version(&crt, ver);
    }

#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    TEST_ASSERT(mbedtls_mpi_read_binary(&serial_mpi, serial_arg->x,
                                        serial_arg->len) == 0);
    TEST_ASSERT(mbedtls_x509write_crt_set_serial(&crt, &serial_mpi) == 0);
#else
    TEST_ASSERT(mbedtls_x509write_crt_set_serial_raw(&crt, serial_arg->x,
                                                     serial_arg->len) == 0);
#endif
    TEST_ASSERT(mbedtls_x509write_crt_set_validity(&crt, not_before,
                                                   not_after) == 0);
    mbedtls_x509write_crt_set_md_alg(&crt, md_type);
    TEST_ASSERT(mbedtls_x509write_crt_set_issuer_name(&crt, issuer_name) == 0);
    TEST_ASSERT(mbedtls_x509write_crt_set_subject_name(&crt, subject_name) == 0);
    mbedtls_x509write_crt_set_subject_key(&crt, &subject_key);

    mbedtls_x509write_crt_set_issuer_key(&crt, key);

    if (crt.version >= MBEDTLS_X509_CRT_VERSION_3) {
        /* For the CA case, a path length of -1 means unlimited. */
        TEST_ASSERT(mbedtls_x509write_crt_set_basic_constraints(&crt, is_ca,
                                                                (is_ca ? -1 : 0)) == 0);
        TEST_ASSERT(mbedtls_x509write_crt_set_subject_key_identifier(&crt) == 0);
        if (auth_ident) {
            TEST_ASSERT(mbedtls_x509write_crt_set_authority_key_identifier(&crt) == 0);
        }
        if (set_key_usage != 0) {
            TEST_ASSERT(mbedtls_x509write_crt_set_key_usage(&crt, key_usage) == 0);
        }
        if (set_cert_type != 0) {
            TEST_ASSERT(mbedtls_x509write_crt_set_ns_cert_type(&crt, cert_type) == 0);
        }
        if (strcmp(ext_key_usage, "NULL") != 0) {
            mbedtls_asn1_sequence exts[2];
            memset(exts, 0, sizeof(exts));

#define SET_OID(x, oid)                \
    do {                               \
        x.len = MBEDTLS_OID_SIZE(oid); \
        x.p   = (unsigned char *) oid;   \
        x.tag = MBEDTLS_ASN1_OID;      \
    }                                  \
    while (0)

            if (strcmp(ext_key_usage, "serverAuth") == 0) {
                SET_OID(exts[0].buf, MBEDTLS_OID_SERVER_AUTH);
            } else if (strcmp(ext_key_usage, "codeSigning,timeStamping") == 0) {
                SET_OID(exts[0].buf, MBEDTLS_OID_CODE_SIGNING);
                exts[0].next = &exts[1];
                SET_OID(exts[1].buf, MBEDTLS_OID_TIME_STAMPING);
            }
            TEST_ASSERT(mbedtls_x509write_crt_set_ext_key_usage(&crt, exts) == 0);
        }
    }

    ret = mbedtls_x509write_crt_pem(&crt, buf, sizeof(buf),
                                    mbedtls_test_rnd_pseudo_rand, &rnd_info);
    TEST_ASSERT(ret == 0);

    pem_len = strlen((char *) buf);

    // check that the rest of the buffer remains clear
    for (buf_index = pem_len; buf_index < sizeof(buf); ++buf_index) {
        TEST_ASSERT(buf[buf_index] == 0);
    }

    if (issuer_key_type != MBEDTLS_PK_RSA) {
        mbedtls_x509_crt crt_parse, trusted;
        uint32_t flags;

        mbedtls_x509_crt_init(&crt_parse);
        mbedtls_x509_crt_init(&trusted);

        TEST_ASSERT(mbedtls_x509_crt_parse_file(&trusted,
                                                cert_verify_file) == 0);
        TEST_ASSERT(mbedtls_x509_crt_parse(&crt_parse,
                                           buf, sizeof(buf)) == 0);

        ret = mbedtls_x509_crt_verify(&crt_parse, &trusted, NULL, NULL, &flags,
                                      NULL, NULL);

        mbedtls_x509_crt_free(&crt_parse);
        mbedtls_x509_crt_free(&trusted);

        TEST_EQUAL(flags, 0);
        TEST_EQUAL(ret, 0);
    } else if (*cert_check_file != '\0') {
        f = fopen(cert_check_file, "r");
        TEST_ASSERT(f != NULL);
        olen = fread(check_buf, 1, sizeof(check_buf), f);
        fclose(f);
        TEST_ASSERT(olen < sizeof(check_buf));

        TEST_EQUAL(olen, pem_len);
        TEST_ASSERT(olen >= pem_len - 1);
        TEST_ASSERT(memcmp(buf, check_buf, pem_len - 1) == 0);
    }

    der_len = mbedtls_x509write_crt_der(&crt, buf, sizeof(buf),
                                        mbedtls_test_rnd_pseudo_rand,
                                        &rnd_info);
    TEST_ASSERT(der_len >= 0);

    if (der_len == 0) {
        goto exit;
    }

    // Not testing against file, check date format
    if (*cert_check_file == '\0') {
        // UTC tag if before 2050, 2 digits less for year
        if (not_before[0] == '2' && (not_before[1] > '0' || not_before[2] > '4')) {
            before_tag = MBEDTLS_ASN1_GENERALIZED_TIME;
        } else {
            before_tag = MBEDTLS_ASN1_UTC_TIME;
            not_before += 2;
        }
        if (not_after[0] == '2' && (not_after[1] > '0' || not_after[2] > '4')) {
            after_tag = MBEDTLS_ASN1_GENERALIZED_TIME;
        } else {
            after_tag = MBEDTLS_ASN1_UTC_TIME;
            not_after += 2;
        }
        end = buf + sizeof(buf);
        for (p = end - der_len; p < end;) {
            tag = *p++;
            sz = *p++;
            if (tag == MBEDTLS_ASN1_UTC_TIME || tag == MBEDTLS_ASN1_GENERALIZED_TIME) {
                // Check correct tag and time written
                TEST_ASSERT(before_tag == tag);
                TEST_ASSERT(memcmp(p, not_before, sz - 1) == 0);
                p += sz;
                tag = *p++;
                sz = *p++;
                TEST_ASSERT(after_tag == tag);
                TEST_ASSERT(memcmp(p, not_after, sz - 1) == 0);
                break;
            }
            // Increment if long form ASN1 length
            if (sz & 0x80) {
                p += sz & 0x0F;
            }
            if (tag != (MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
                p += sz;
            }
        }
        TEST_ASSERT(p < end);
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, result length isn't
    // deterministic over multiple runs, removing a single byte isn't enough to
    // go into the MBEDTLS_ERR_ASN1_BUF_TOO_SMALL error case
    if (issuer_key_type != MBEDTLS_PK_RSA) {
        der_len /= 2;
    } else
#endif
    der_len -= 1;

    ret = mbedtls_x509write_crt_der(&crt, buf, (size_t) (der_len),
                                    mbedtls_test_rnd_pseudo_rand, &rnd_info);
    TEST_ASSERT(ret == MBEDTLS_ERR_ASN1_BUF_TOO_SMALL);

exit:
    mbedtls_x509write_crt_free(&crt);
    mbedtls_pk_free(&issuer_key_alt);
    mbedtls_pk_free(&subject_key);
    mbedtls_pk_free(&issuer_key);
#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    mbedtls_mpi_free(&serial_mpi);
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_destroy_key(key_id);
#endif
    USE_PSA_DONE();
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_WRITE_C */
void x509_set_serial_check()
{
    mbedtls_x509write_cert ctx;
    uint8_t invalid_serial[MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN + 1];

    memset(invalid_serial, 0x01, sizeof(invalid_serial));

#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    mbedtls_mpi serial_mpi;

    mbedtls_mpi_init(&serial_mpi);
    TEST_EQUAL(mbedtls_mpi_read_binary(&serial_mpi, invalid_serial,
                                       sizeof(invalid_serial)), 0);
    TEST_EQUAL(mbedtls_x509write_crt_set_serial(&ctx, &serial_mpi),
               MBEDTLS_ERR_X509_BAD_INPUT_DATA);
#endif

    TEST_EQUAL(mbedtls_x509write_crt_set_serial_raw(&ctx, invalid_serial,
                                                    sizeof(invalid_serial)),
               MBEDTLS_ERR_X509_BAD_INPUT_DATA);

exit:
#if defined(MBEDTLS_TEST_DEPRECATED) && defined(MBEDTLS_BIGNUM_C)
    mbedtls_mpi_free(&serial_mpi);
#else
    ;
#endif
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_X509_CREATE_C:MBEDTLS_X509_USE_C */
void mbedtls_x509_string_to_names(char *name, char *parsed_name, int result
                                  )
{
    int ret;
    size_t len = 0;
    mbedtls_asn1_named_data *names = NULL;
    mbedtls_x509_name parsed, *parsed_cur, *parsed_prv;
    unsigned char buf[1024], out[1024], *c;

    memset(&parsed, 0, sizeof(parsed));
    memset(out, 0, sizeof(out));
    memset(buf, 0, sizeof(buf));
    c = buf + sizeof(buf);

    ret = mbedtls_x509_string_to_names(&names, name);
    TEST_ASSERT(ret == result);

    if (ret != 0) {
        goto exit;
    }

    ret = mbedtls_x509_write_names(&c, buf, names);
    TEST_ASSERT(ret > 0);

    TEST_ASSERT(mbedtls_asn1_get_tag(&c, buf + sizeof(buf), &len,
                                     MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE) == 0);
    TEST_ASSERT(mbedtls_x509_get_name(&c, buf + sizeof(buf), &parsed) == 0);

    ret = mbedtls_x509_dn_gets((char *) out, sizeof(out), &parsed);
    TEST_ASSERT(ret > 0);

    TEST_ASSERT(strcmp((char *) out, parsed_name) == 0);

exit:
    mbedtls_asn1_free_named_data_list(&names);

    parsed_cur = parsed.next;
    while (parsed_cur != 0) {
        parsed_prv = parsed_cur;
        parsed_cur = parsed_cur->next;
        mbedtls_free(parsed_prv);
    }
}
/* END_CASE */