CURLOPT_SSL_EC_CURVES(3) Library Functions Manual CURLOPT_SSL_EC_CURVES(3) NAME CURLOPT_SSL_EC_CURVES - key exchange curves SYNOPSIS #include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_EC_CURVES, char *list); DESCRIPTION Pass a string as parameter with a colon delimited list of Elliptic curve (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). 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 restore back to internal default. DEFAULT "", embedded in SSL backend PROTOCOLS This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only This option works only with the following TLS backends: OpenSSL and wolfSSL 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_SSL_EC_CURVES, "X25519:P-521"); result = curl_easy_perform(curl); curl_easy_cleanup(curl); } } AVAILABILITY Added in curl 7.73.0 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). SEE ALSO CURLOPT_SSL_CIPHER_LIST(3), CURLOPT_SSL_OPTIONS(3), CURLOPT_TLS13_CI- PHERS(3) libcurl 2026-08-27 CURLOPT_SSL_EC_CURVES(3)
NAME | SYNOPSIS | DESCRIPTION | DEFAULT | PROTOCOLS | EXAMPLE | AVAILABILITY | RETURN VALUE | SEE ALSO
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