CURLOPT_SSLENGINE_DEFAULT(3)

✨ CURLOPT_SSLENGINE_DEFAULT — make SSL engine default ✨

okay bestie, so this little cutie lives in the libcurl family of manual pages (libcurl, Library Functions Manual, if we're being official about it 🎀) and honestly? it's giving "small but mighty." let me tell you everything 💅

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✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLENGINE_DEFAULT, long val);

like, that's the whole vibe. one curl_easy_setopt call, CURL *handle, a long val, and we're done 🫶

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🌸 DESCRIPTION 🌸

so you pass a long set to 1 and that makes the already-specified crypto engine the default for (asymmetric) crypto operations. that's it. that's the whole job. main character energy but make it one line 🔥

ngl, this option has no effect unless you set it after CURLOPT_SSLENGINE(3). literally. it does nothing on its own — it's a sequel, not a standalone. 😭

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🦋 DEFAULT 🦋

None — yeah, nothing. no default behavior, no secret fallback. you gotta actually ask for it, iykyk 🙈

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💜 PROTOCOLS 💜

this functionality affects all TLS based protocols, and when I say all I mean it:

• HTTPS
• FTPS
• IMAPS
• POP3S
• SMTPS
• etc. (you get the picture ✨)

okay important vibe check though: this option works only with the following TLS backends: OpenSSL. so if you're on anything else, it's not gonna slay for you 💀

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🌈 EXAMPLE 🌈

here's the whole little program, copy it exactly bestie, don't freestyle it:

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_SSLENGINE, "dynamic");
    curl_easy_setopt(curl, CURLOPT_SSLENGINE_DEFAULT, 1L);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

see how CURLOPT_SSLENGINE comes first and CURLOPT_SSLENGINE_DEFAULT comes after? that's the order, periodt 👑

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⭐ AVAILABILITY ⭐

added in curl 7.9.3 — an absolute icon from back in the day, still serving 💖

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🔥 RETURN VALUE 🔥

here's the full rundown of what you can get back, no cap:

• CURLE_OK — Engine set as default. slay, it worked 💅
• CURLE_SSL_ENGINE_SETFAILED — Engine could not be set as default. the engine said no 😭
• CURLE_NOT_BUILT_IN — Option not built in, OpenSSL is not the SSL backend. wrong backend, wrong timeline 💀
• CURLE_UNKNOWN_OPTION — Option not recognized. doesn't know her 🫠
• CURLE_OUT_OF_MEMORY — Insufficient heap space. the heap is full, she's going through it 🙈

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🌸 SEE ALSO 🌸

• CURLOPT_SSLCERT(3)
• CURLOPT_SSLENGINE(3)

go read those too, they're literally the prequels 🦋

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and that's the whole page, bestie! this came straight from the libcurl manual, dated 2026-10-12 — yeah, she's got a timestamp and everything 👑 take care of her, set your engine first, and remember: CURLOPT_SSLENGINE_DEFAULT is nothing without CURLOPT_SSLENGINE. tandem ride fr fr 💜✨🎀