CURLOPT_SSLCERT(3) Library Functions Manual 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
P12 on Secure Transport and PEM on other engines, and can be changed
with CURLOPT_SSLCERTTYPE(3).
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 expres-
sion to a certificate store. (You can import PFX to a store first). You
can use "<store location>\<store name>\<thumbprint>" to refer to a cer-
tificate in the system certificates store, for example, "Curren-
tUser\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, Curren-
tUserGroupPolicy, LocalMachineGroupPolicy, LocalMachineEnterprise.
Schannel also support P12 certificate file, with the string P12 speci-
fied 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.
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
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 2026-07-12 CURLOPT_SSLCERT(3)
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