CURLOPT_PROXY_SSLCERTTYPE(3)

✨ CURLOPT_PROXY_SSLCERTTYPE(3) ✨

Okay bestie, gather round, because today we're talking about CURLOPT_PROXY_SSLCERTTYPE from the libcurl Library Functions Manual, and honestly? It's giving "small but mighty" 💅

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🌸 NAME 🌸

CURLOPT_PROXY_SSLCERTTYPE — the type of the proxy client SSL certificate 🎀

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🦋 SYNOPSIS 🦋

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSLCERTTYPE, char *type);

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💖 DESCRIPTION 💖

So basically, you pass in a pointer to a null-terminated string as the parameter. That string should be the format of your client certificate — the one you use when connecting to an HTTPS proxy. 🔥

The supported formats are "PEM" and "DER", except with Schannel. OpenSSL and Schannel also support "P12" for PKCS#12-encoded files. Iconic.

The application does not have to keep the string around after setting this option — so you can let it go, no strings attached (pun absolutely intended 😭).

And listen: using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again. Periodt. 💀

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✨ DEFAULT ✨

"PEM" — the default is literally right there, no cap.

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🌈 PROTOCOLS 🌈

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. All the secure ones, slay. 🔐

Heads up bestie: this option works only with the following TLS backends: GnuTLS, OpenSSL, Schannel, mbedTLS and wolfSSL 👑

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🍓 EXAMPLE 🍓

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_SSLCERTTYPE, "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);
  }
}

Look at that — the whole proxy TLS situation set up in one go. Main character energy fr fr. 💜

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🧚 AVAILABILITY 🧚

Added in curl 7.52.0 — a classic, honestly.

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💅 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) if you need the full tea.

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👑 SEE ALSO 👑

• CURLOPT_PROXY_SSLCERT(3)
• CURLOPT_PROXY_SSLKEY(3)
• CURLOPT_SSLCERTTYPE(3)

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And that's the whole vibe check, bestie — libcurl, dated 2026-10-12, page CURLOPT_PR...SSLCERTTYPE(3). Go forth and certify your proxies. Slay! 💖✨🎀