Help regarding extracting key from PEM file

[ranjithravitk]

Hi I am implementing elgamal provider. I am reaching out as I am facing an issue you might have encountered while developing oqs. I have generated the private key PEM file. Now to generate the public key, I decoded the private key and passing it back to openSSL like this:

  object_type=OSSL_OBJECT_PKEY;
        params[0] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &object_type);
        params[1] = OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_TYPE,
                                                     "ELGAMAL", 0);
        params[2] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_REFERENCE,
                                                      &kdata, sizeof(kdata));
        params[3] = OSSL_PARAM_construct_end();
        if(!data_cb(params,data_cbarg))
          goto err;

but the default file STORE is not able to export it and throwing me an error. To be precise,

struct evp_keymgmt_util_try_import_data_st import_data;
OSSL_FUNC_store_export_object_fn *export_object =
ctx->fetched_loader->p_export_object;

        import_data.keymgmt = keymgmt;
        import_data.keydata = NULL;
        import_data.selection = OSSL_KEYMGMT_SELECT_ALL;

        if (export_object != NULL) {
            /*
             * No need to check for errors here, the value of
             * |import_data.keydata| is as much an indicator.
             */
            (void)export_object(ctx->loader_ctx,
                                data->ref, data->ref_size,
                                &evp_keymgmt_util_try_import,
                                &import_data);
        }

        keydata = import_data.keydata;
    }

this is giving keydata as null as the export_object is NULL. I am just reaching out to understand how you guys resolved it. It will be really helpful if you can give me any tips at all. Thank you so much and sorry for any inconvenience.