curl/docs/libcurl/opts/CURLOPT_SSL_EC_CURVES.md

---

c: Copyright (C) Daniel Stenberg, daniel@haxx.se, et al. SPDX-License-Identifier: curl Title: CURLOPT_SSL_EC_CURVES Section: 3 Source: libcurl See-also:

• CURLOPT_SSL_CIPHER_LIST (3)
• CURLOPT_SSL_OPTIONS (3)
• CURLOPT_TLS13_CIPHERS (3) Protocol:
• TLS TLS-backend:
• OpenSSL
• wolfSSL ---

NAME

CURLOPT_SSL_EC_CURVES - key exchange curves

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_EC_CURVES, char *alg_list);

DESCRIPTION

Pass a string as parameter with a colon delimited list of (EC) algorithms. This option defines the client's key exchange algorithms in the SSL handshake (if the SSL backend libcurl is built to use supports it).

DEFAULT

"", embedded in SSL backend

EXAMPLE

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_SSL_EC_CURVES, "X25519:P-521");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

AVAILABILITY

Added in 7.73.0. Supported by the OpenSSL backend.

RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.