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CURLOPT_KEYPASSWD - set passphrase to private key #include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_KEYPASSWD, char *pwd); Pass a pointer to a null-terminated string as parameter. It will be used as the password required to use the CURLOPT_SSLKEY(3) or CURLOPT_SSH_PRIVATE_KEYFILE(3) private key. You never needed a pass phrase to load a certificate but you need one to load your private key. The application does not have to keep the string around after setting this option. NULL All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

CURL *curl = curl_easy_init();
if(curl) {
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
 curl_easy_setopt(curl, CURLOPT_SSLCERT, "client.pem");
 curl_easy_setopt(curl, CURLOPT_SSLKEY, "key.pem");
 curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "superman");
 ret = curl_easy_perform(curl);
 curl_easy_cleanup(curl);
}

This option was known as CURLOPT_SSLKEYPASSWD up to 7.16.4 and CURLOPT_SSLCERTPASSWD up to 7.9.2. Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space. CURLOPT_SSLKEY "(3), " CURLOPT_SSH_PRIVATE_KEYFILE "(3), "