CURLOPT_PROXY_SSLCERT - HTTPS proxy client certificate

Added in curl 7.52.0

NULL

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 filename of your client certificate used to connect to the HTTPS proxy. The default format is "P12" on Secure Transport and "PEM" on other engines, and can be changed with CURLOPT_PROXY_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. When using a client certificate, you most likely also need to provide a private key with CURLOPT_PROXY_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.

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_KEYPASSWD, "s3cret"); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } }

CURLOPT_PROXY_SSLCERT - HTTPS proxy client certificate

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

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).

CURLOPT_PROXY_SSLCERTTYPE(3), CURLOPT_PROXY_SSLKEY(3), CURLOPT_SSLCERT(3) libcurl 2025-06-16 CURLOPT_PROXY_SSLCERT(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLCERT, char *cert);