---
name: "CURLOPT_PROXY_SSLKEYTYPE"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_PROXY_SSLKEYTYPE"
---

# CURLOPT\_PROXY\_SSLKEYTYPE(3)

type of the proxy private key file

## NAME

CURLOPT\_PROXY\_SSLKEYTYPE - type of the proxy private key file

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLKEYTYPE, char *type);
```

## DESCRIPTION

This option is for connecting to an HTTPS proxy, not an HTTPS server.

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" and "ENG".

The application does not have to keep the string around after setting this option.

## PROTOCOLS

Used with HTTPS proxy

## 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_PROXY, "https://proxy");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERT, "client.pem");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEY, "key.pem");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEYTYPE, "PEM");
    curl_easy_setopt(curl, CURLOPT_PROXY_KEYPASSWD, "s3cret");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in 7.52.0

## RETURN VALUE

Returns CURLE\_OK if TLS is supported, CURLE\_UNKNOWN\_OPTION if not, or CURLE\_OUT\_OF\_MEMORY if there was insufficient heap space.

## SEE ALSO

[**CURLOPT\_PROXY\_SSLCERT**(3)](/CURLOPT_PROXY_SSLCERT/3.md), [**CURLOPT\_PROXY\_SSLKEY**(3)](/CURLOPT_PROXY_SSLKEY/3.md), [**CURLOPT\_SSLKEYTYPE**(3)](/CURLOPT_SSLKEYTYPE/3.md)