int cert_stuff(struct Curl_easy *data,
               SSL_CTX* ctx,
               char *cert_file,
               BIO *cert_bio,
               const char *cert_type,
               char *key_file,
               BIO* key_bio,
               const char *key_type,
               char *key_passwd)
{
  char error_buffer[256];
  bool check_privkey = TRUE;

  int file_type = do_file_type(cert_type);

  if(cert_file || cert_bio || (file_type == SSL_FILETYPE_ENGINE)) {
    SSL *ssl;
    X509 *x509;
    int cert_done = 0;
    int cert_use_result;

    if(key_passwd) {
      /* set the password in the callback userdata */
      SSL_CTX_set_default_passwd_cb_userdata(ctx, key_passwd);
      /* Set passwd callback: */
      SSL_CTX_set_default_passwd_cb(ctx, passwd_callback);
    }


    switch(file_type) {
    case SSL_FILETYPE_PEM:
      /* SSL_CTX_use_certificate_chain_file() only works on PEM files */
      cert_use_result = cert_bio ?
          SSL_CTX_use_certificate_chain_bio(ctx, cert_bio, key_passwd) :
          SSL_CTX_use_certificate_chain_file(ctx, cert_file);
      if(cert_use_result != 1) {
        failf(data,
              "could not load PEM client certificate, " OSSL_PACKAGE
              " error %s, "
              "(no key found, wrong pass phrase, or wrong file format?)",
              ossl_strerror(ERR_get_error(), error_buffer,
                            sizeof(error_buffer)) );
        return 0;
      }
      break;

    case SSL_FILETYPE_ASN1:
      /* SSL_CTX_use_certificate_file() works with either PEM or ASN1, but
         we use the case above for PEM so this can only be performed with
         ASN1 files. */

      cert_use_result = cert_bio ?
          SSL_CTX_use_certificate_bio(ctx, cert_bio,
                                      file_type, key_passwd) :
          SSL_CTX_use_certificate_file(ctx, cert_file, file_type);
      if(cert_use_result != 1) {
        failf(data,
              "could not load ASN1 client certificate, " OSSL_PACKAGE
              " error %s, "
              "(no key found, wrong pass phrase, or wrong file format?)",
              ossl_strerror(ERR_get_error(), error_buffer,
                            sizeof(error_buffer)) );
        return 0;
      }
      break;
    case SSL_FILETYPE_ENGINE:
#if defined(USE_OPENSSL_ENGINE) && defined(ENGINE_CTRL_GET_CMD_FROM_NAME)
      {
        /* Implicitly use pkcs11 engine if none was provided and the
         * cert_file is a PKCS#11 URI */
        if(!data->state.engine) {
          if(is_pkcs11_uri(cert_file)) {
            if(ossl_set_engine(data, "pkcs11") != CURLE_OK) {
              return 0;
            }
          }
        }

        if(data->state.engine) {
          const char *cmd_name = "LOAD_CERT_CTRL";
          struct {
            const char *cert_id;
            X509 *cert;
          } params;

          params.cert_id = cert_file;
          params.cert = NULL;

          /* Does the engine supports LOAD_CERT_CTRL ? */
          if(!ENGINE_ctrl(data->state.engine, ENGINE_CTRL_GET_CMD_FROM_NAME,
                          0, (void *)cmd_name, NULL)) {
            failf(data, "ssl engine does not support loading certificates");
            return 0;
          }

          /* Load the certificate from the engine */
          if(!ENGINE_ctrl_cmd(data->state.engine, cmd_name,
                              0, &params, NULL, 1)) {
            failf(data, "ssl engine cannot load client cert with id"
                  " '%s' [%s]", cert_file,
                  ossl_strerror(ERR_get_error(), error_buffer,
                                sizeof(error_buffer)));
            return 0;
          }

          if(!params.cert) {
            failf(data, "ssl engine didn't initialized the certificate "
                  "properly.");
            return 0;
          }

          if(SSL_CTX_use_certificate(ctx, params.cert) != 1) {
            failf(data, "unable to set client certificate");
            X509_free(params.cert);
            return 0;
          }
          X509_free(params.cert); /* we don't need the handle any more... */
        }
        else {
          failf(data, "crypto engine not set, can't load certificate");
          return 0;
        }
      }
      break;
#else
      failf(data, "file type ENG for certificate not implemented");
      return 0;
#endif

    case SSL_FILETYPE_PKCS12:
    {
      BIO *fp = NULL;
      PKCS12 *p12 = NULL;
      EVP_PKEY *pri;
      STACK_OF(X509) *ca = NULL;
      if(!cert_bio) {
        fp = BIO_new(BIO_s_file());
        if(fp == NULL) {
          failf(data,
                "BIO_new return NULL, " OSSL_PACKAGE
                " error %s",
                ossl_strerror(ERR_get_error(), error_buffer,
                              sizeof(error_buffer)) );
          return 0;
        }

        if(BIO_read_filename(fp, cert_file) <= 0) {
          failf(data, "could not open PKCS12 file '%s'", cert_file);
          BIO_free(fp);
          return 0;
        }
      }

      p12 = d2i_PKCS12_bio(cert_bio ? cert_bio : fp, NULL);
      if(fp)
        BIO_free(fp);

      if(!p12) {
        failf(data, "error reading PKCS12 file '%s'",
              cert_bio ? "(memory blob)" : cert_file);
        return 0;
      }

      PKCS12_PBE_add();

      if(!PKCS12_parse(p12, key_passwd, &pri, &x509,
                       &ca)) {
        failf(data,
              "could not parse PKCS12 file, check password, " OSSL_PACKAGE
              " error %s",
              ossl_strerror(ERR_get_error(), error_buffer,
                            sizeof(error_buffer)) );
        PKCS12_free(p12);
        return 0;
      }

      PKCS12_free(p12);

      if(SSL_CTX_use_certificate(ctx, x509) != 1) {
        failf(data,
              "could not load PKCS12 client certificate, " OSSL_PACKAGE
              " error %s",
              ossl_strerror(ERR_get_error(), error_buffer,
                            sizeof(error_buffer)) );
        goto fail;
      }

      if(SSL_CTX_use_PrivateKey(ctx, pri) != 1) {
        failf(data, "unable to use private key from PKCS12 file '%s'",
              cert_file);
        goto fail;
      }

      if(!SSL_CTX_check_private_key (ctx)) {
        failf(data, "private key from PKCS12 file '%s' "
              "does not match certificate in same file", cert_file);
        goto fail;
      }
      /* Set Certificate Verification chain */
      if(ca) {
        while(sk_X509_num(ca)) {
          /*
           * Note that sk_X509_pop() is used below to make sure the cert is
           * removed from the stack properly before getting passed to
           * SSL_CTX_add_extra_chain_cert(), which takes ownership. Previously
           * we used sk_X509_value() instead, but then we'd clean it in the
           * subsequent sk_X509_pop_free() call.
           */
          X509 *x = sk_X509_pop(ca);
          if(!SSL_CTX_add_client_CA(ctx, x)) {
            X509_free(x);
            failf(data, "cannot add certificate to client CA list");
            goto fail;
          }
          if(!SSL_CTX_add_extra_chain_cert(ctx, x)) {
            X509_free(x);
            failf(data, "cannot add certificate to certificate chain");
            goto fail;
          }
        }
      }

      cert_done = 1;
  fail:
      EVP_PKEY_free(pri);
      X509_free(x509);
#ifdef USE_AMISSL
      sk_X509_pop_free(ca, Curl_amiga_X509_free);
#else
      sk_X509_pop_free(ca, X509_free);
#endif
      if(!cert_done)
        return 0; /* failure! */
      break;
    }
    default:
      failf(data, "not supported file type '%s' for certificate", cert_type);
      return 0;
    }

    if((!key_file) && (!key_bio)) {
      key_file = cert_file;
      key_bio = cert_bio;
    }
    else
      file_type = do_file_type(key_type);

    switch(file_type) {
    case SSL_FILETYPE_PEM:
      if(cert_done)
        break;
      /* FALLTHROUGH */
    case SSL_FILETYPE_ASN1:
      cert_use_result = key_bio ?
        SSL_CTX_use_PrivateKey_bio(ctx, key_bio, file_type, key_passwd) :
        SSL_CTX_use_PrivateKey_file(ctx, key_file, file_type);
      if(cert_use_result != 1) {
        failf(data, "unable to set private key file: '%s' type %s",
              key_file?key_file:"(memory blob)", key_type?key_type:"PEM");
        return 0;
      }
      break;
    case SSL_FILETYPE_ENGINE:
#ifdef USE_OPENSSL_ENGINE
      {                         /* XXXX still needs some work */
        EVP_PKEY *priv_key = NULL;

        /* Implicitly use pkcs11 engine if none was provided and the
         * key_file is a PKCS#11 URI */
        if(!data->state.engine) {
          if(is_pkcs11_uri(key_file)) {
            if(ossl_set_engine(data, "pkcs11") != CURLE_OK) {
              return 0;
            }
          }
        }

        if(data->state.engine) {
          UI_METHOD *ui_method =
            UI_create_method((char *)"curl user interface");
          if(!ui_method) {
            failf(data, "unable do create " OSSL_PACKAGE
                  " user-interface method");
            return 0;
          }
          UI_method_set_opener(ui_method, UI_method_get_opener(UI_OpenSSL()));
          UI_method_set_closer(ui_method, UI_method_get_closer(UI_OpenSSL()));
          UI_method_set_reader(ui_method, ssl_ui_reader);
          UI_method_set_writer(ui_method, ssl_ui_writer);
          /* the typecast below was added to please mingw32 */
          priv_key = (EVP_PKEY *)
            ENGINE_load_private_key(data->state.engine, key_file,
                                    ui_method,
                                    key_passwd);
          UI_destroy_method(ui_method);
          if(!priv_key) {
            failf(data, "failed to load private key from crypto engine");
            return 0;
          }
          if(SSL_CTX_use_PrivateKey(ctx, priv_key) != 1) {
            failf(data, "unable to set private key");
            EVP_PKEY_free(priv_key);
            return 0;
          }
          EVP_PKEY_free(priv_key);  /* we don't need the handle any more... */
        }
        else {
          failf(data, "crypto engine not set, can't load private key");
          return 0;
        }
      }
      break;
#else
      failf(data, "file type ENG for private key not supported");
      return 0;
#endif
    case SSL_FILETYPE_PKCS12:
      if(!cert_done) {
        failf(data, "file type P12 for private key not supported");
        return 0;
      }
      break;
    default:
      failf(data, "not supported file type for private key");
      return 0;
    }

    ssl = SSL_new(ctx);
    if(!ssl) {
      failf(data, "unable to create an SSL structure");
      return 0;
    }

    x509 = SSL_get_certificate(ssl);

    /* This version was provided by Evan Jordan and is supposed to not
       leak memory as the previous version: */
    if(x509) {
      EVP_PKEY *pktmp = X509_get_pubkey(x509);
      EVP_PKEY_copy_parameters(pktmp, SSL_get_privatekey(ssl));
      EVP_PKEY_free(pktmp);
    }

#if !defined(OPENSSL_NO_RSA) && !defined(OPENSSL_IS_BORINGSSL)
    {
      /* If RSA is used, don't check the private key if its flags indicate
       * it doesn't support it. */
      EVP_PKEY *priv_key = SSL_get_privatekey(ssl);
      int pktype;
#ifdef HAVE_OPAQUE_EVP_PKEY
      pktype = EVP_PKEY_id(priv_key);
#else
      pktype = priv_key->type;
#endif
      if(pktype == EVP_PKEY_RSA) {
        RSA *rsa = EVP_PKEY_get1_RSA(priv_key);
        if(RSA_flags(rsa) & RSA_METHOD_FLAG_NO_CHECK)
          check_privkey = FALSE;
        RSA_free(rsa); /* Decrement reference count */
      }
    }
#endif

    SSL_free(ssl);

    /* If we are using DSA, we can copy the parameters from
     * the private key */

    if(check_privkey == TRUE) {
      /* Now we know that a key and cert have been set against
       * the SSL context */
      if(!SSL_CTX_check_private_key(ctx)) {
        failf(data, "Private key does not match the certificate public key");
        return 0;
      }
    }
  }
  return 1;
}