curl / libcurl / API / curl_easy_setopt / CURLOPT_SSLCERT

CURLOPT_SSLCERT explained

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 P12 on Secure Transport and PEM on other engines, and can be changed with CURLOPT_SSLCERTTYPE.

With Secure Transport, this can also be the nickname of the certificate you wish to authenticate with as it is named in the security database. If you want to use a file from the current directory, please precede it with ./ prefix, in order to avoid confusion with a nickname.

(Schannel only) 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.

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

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: GnuTLS, OpenSSL, Schannel, Secure Transport, 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 7.1

Return value

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