CURLOPT_SSLKEY(3) Library Functions Manual CURLOPT_SSLKEY(3)

CURLOPT_SSLKEY - private key file for TLS and SSL client cert

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLKEY, char *keyfile);

Pass a pointer to a null-terminated string as parameter. The string should be the filename of your private key. The default format is "PEM" and can be changed with CURLOPT_SSLKEYTYPE(3).

(Windows, iOS and Mac OS X) This option is ignored by Secure Transport and Schannel SSL backends because they expect the private key to be already present in the key-chain or PKCS#12 file containing the certificate.

The application does not have to keep the string around after setting this option.


All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: OpenSSL, Schannel, mbedTLS and wolfSSL

int main(void)
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "");
    curl_easy_setopt(curl, CURLOPT_SSLCERT, "client.pem");
    curl_easy_setopt(curl, CURLOPT_SSLKEY, "key.pem");
    curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "s3cret");
    res = curl_easy_perform(curl);

If built TLS enabled.

Returns CURLE_OK if TLS is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.


2024-05-22 libcurl