---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_PROXY_SSLKEY
Section: 3
Source: libcurl
See-also:
  - CURLOPT_PROXY_SSLCERT (3)
  - CURLOPT_PROXY_SSLKEYTYPE (3)
  - CURLOPT_SSLCERT (3)
  - CURLOPT_SSLKEY (3)
  - CURLOPT_SSLKEYTYPE (3)
Protocol:
  - TLS
TLS-backend:
  - OpenSSL
  - mbedTLS
  - Schannel
  - wolfSSL
Added-in: 7.52.0
---

# NAME

CURLOPT_PROXY_SSLKEY - private key file for HTTPS proxy client cert

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLKEY, char *keyfile);
~~~

# DESCRIPTION

Pass a pointer to a null-terminated string as parameter. The string should be
the filename of your private key used for connecting to the HTTPS proxy. The
default format is "PEM" and can be changed with
CURLOPT_PROXY_SSLKEYTYPE(3).

This option is ignored by the Schannel backend because it expects the private
key to be already present in the key chain or PKCS#12 file containing the
certificate.

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%

# EXAMPLE

~~~c
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_PROXY, "https://proxy.example");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERT, "client.pem");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEY, "key.pem");
    curl_easy_setopt(curl, CURLOPT_PROXY_KEYPASSWD, "s3cret");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
~~~

# %AVAILABILITY%

# 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).