CURLOPT_TLSAUTH_USERNAME(3)

✨ CURLOPT_TLSAUTH_USERNAME ✨

okay so bestie, this is a page straight out of the libcurl manual (the Library Functions Manual, if we're being fancy 💅) and it's all about one little option: CURLOPT_TLSAUTH_USERNAME. Basically the username you hand over for TLS authentication. Let's get into it 🎀

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🌸 NAME 🌸

CURLOPT_TLSAUTH_USERNAME — the username you use for TLS authentication. yep, that's it, that's the whole vibe ✨

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🦋 SYNOPSIS 🦋

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TLSAUTH_USERNAME, char *user);

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💖 DESCRIPTION 💖

so you pass a char pointer as the parameter, right? and it should point to a null-terminated username — the one you wanna use for whichever TLS authentication method you picked with CURLOPT_TLSAUTH_TYPE(3). lowkey important: this option requires that you also set CURLOPT_TLSAUTH_PASSWORD(3). they're a package deal, fr fr 🫶

the good news? your application does not have to keep the string around after setting this option. set it and forget it, icon behavior honestly ✨

if you use this option multiple times, the last set string wins and overrides all the previous ones. and if you set it to NULL, it disables it again. clean. no notes 👑

⚠️ heads up bestie: this feature relies on TLS SRP, which does not work with TLS 1.3. like, at all. so keep that in mind 💀

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🎀 DEFAULT 🎀

NULL

(yeah, nothing set by default — it's giving empty-handed 🙈)

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🌈 PROTOCOLS 🌈

this lil functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. the whole crew 🫶

and ngl, this option only works with these specific TLS backends: GnuTLS and OpenSSL 💅

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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_TLSAUTH_TYPE, "SRP");
    curl_easy_setopt(curl, CURLOPT_TLSAUTH_USERNAME, "user");
    curl_easy_setopt(curl, CURLOPT_TLSAUTH_PASSWORD, "secret");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

see how CURLOPT_TLSAUTH_TYPE, CURLOPT_TLSAUTH_USERNAME and CURLOPT_TLSAUTH_PASSWORD all show up together? that's the trio, the main character energy squad 👑

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⭐ AVAILABILITY ⭐

added in curl 7.21.4 — a classic, honestly 🌸

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💜 RETURN VALUE 💜

curl_easy_setopt(3) returns a CURLcode that tells you whether it went great or... didn't 😭

• CURLE_OK (0) means everything was OK ✨
• anything non-zero means an error occurred — go check libcurl-errors(3) for the deets

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🔥 SEE ALSO 🔥

• CURLOPT_TLSAUTH_PASSWORD(3)
• CURLOPT_TLSAUTH_TYPE(3)

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okay that's the whole page, bestie, you ate that 🫶 this was libcurl, dated 2026-10-12, page CURLOPT_TLSAUTH_USERNAME(3) — now go set your TLS auth username and slay 💅✨