NAME

       CURLOPT_SSLKEY - private key file for TLS and SSL client cert

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLKEY, char *keyfile);

DESCRIPTION

       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) This option is ignored by the Schannel SSL backend because it expects 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.

       Using  this option multiple times makes the last set string override the previous ones. Set it to NULL to
       disable its use again.

DEFAULT

       NULL

PROTOCOLS

       This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

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

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
           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);
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY

       Added in curl 7.9.3

RETURN VALUE

       curl_easy_setopt(3) returns a CURLcode indicating success or error.

       CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO

       CURLOPT_SSLCERT(3), CURLOPT_SSLKEYTYPE(3), CURLOPT_SSLKEY_BLOB(3)

libcurl                                            2025-11-07                                  CURLOPT_SSLKEY(3)