CURLOPT_SSLCERT(3) Introduction to Library Functions CURLOPT_SSLCERT(3)

NAME


CURLOPT_SSLCERT - SSL client certificate

SYNOPSIS


#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLCERT, char *cert);

DESCRIPTION


Pass a pointer to a null-terminated string as parameter. The string
should be the filename of your client certificate. The default format
is PEM but can be changed with CURLOPT_SSLCERTTYPE(3).

(Schannel) Client certificates can be specified by a path expression
to a certificate store. (You can import PFX to a store first). You
can use "<store location>\<store name>\<thumbprint>" to refer to a
certificate in the system certificates store, for example,
"CurrentUser\MY\934a7ac6f8a5d5". The thumbprint is usually a SHA-1
hex string which you can see in certificate details. Following store
locations are supported: CurrentUser, LocalMachine, CurrentService,
Services, CurrentUserGroupPolicy, LocalMachineGroupPolicy,
LocalMachineEnterprise. Schannel also support P12 certificate file,
with the string P12 specified with CURLOPT_SSLCERTTYPE(3).

When using a client certificate, you most likely also need to provide
a private key with CURLOPT_SSLKEY(3).

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.

All TLS backends support this option.

EXAMPLE


int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;
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");
result = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY


Added in curl 7.1

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_KEYPASSWD(3), CURLOPT_SSLCERTTYPE(3), CURLOPT_SSLKEY(3)

libcurl 2026-01-08 CURLOPT_SSLCERT(3)