CURLOPT_SSLKEYTYPE(3) Library Functions Manual CURLOPT_SSLKEYTYPE(3)
NAME
CURLOPT_SSLKEYTYPE - type of the private key file
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLKEYTYPE, char *type);
DESCRIPTION
Pass a pointer to a null-terminated string as parameter. The string
should be the format of your private key. Supported formats are "PEM",
"DER", "ENG" and "PROV".
The format "ENG" enables you to load the private key from a crypto en-
gine. In this case CURLOPT_SSLKEY(3) is used as an identifier passed to
the engine. You have to set the crypto engine with CURLOPT_SSLENGINE(3).
The format "PROV" enables you to load the private key from a crypto
provider (Added in 8.12.0). In this case CURLOPT_SSLKEY(3) is used as an
identifier passed to the provider.
The "DER" format does not work with OpenSSL.
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 restore to internal default.
DEFAULT
"PEM"
PROTOCOLS
This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS,
POP3S, SMTPS etc.
This option works only with the following TLS backends: BearSSL, OpenSSL
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_SSLKEYTYPE, "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_PROXY_SSLKEYTYPE(3), CURLOPT_SSLCERT(3), CURLOPT_SSLKEY(3)
libcurl 2026-07-12 CURLOPT_SSLKEYTYPE(3)
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