CURLOPT_RANDOM_FILE − specify a source for random data
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RANDOM_FILE, char *path);
Pass a char * to a zero terminated file name. The file will be used to read from to seed the random engine for SSL and more.
NULL, not used
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient heap space.