CURLOPT_TLS13_CIPHERS - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TLS13_CIPHERS, char *list);

Pass a char pointer, pointing to a null-terminated string holding the list of cipher suites to use for the TLS 1.3 connection. The list must be syntactically correct, it consists of one or more cipher suite strings separated by colons.

For setting TLS 1.2 (1.1, 1.0) ciphers see CURLOPT_SSL_CIPHER_LIST(3).

A valid example of a cipher list is:

"TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256"

Find more details about cipher lists on this URL:

https://curl.se/docs/ssl-ciphers.html

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 to internal default.

NULL, use internal built-in

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: OpenSSL, Schannel, mbedTLS, rustls and wolfSSL

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_TLS13_CIPHERS,
                     "TLS_CHACHA20_POLY1305_SHA256");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

OpenSSL support added in 7.61.0, available when built with OpenSSL >= 1.1.1. Schannel support added in 7.85.0. LibreSSL support added in 8.3.0, available when built with LibreSSL >= 3.4.1. wolfSSL support added in 8.10.0. mbedTLS support added in 8.10.0, available when built with mbedTLS >= 3.6.0. Rustls support added in 8.10.0.

Before curl 8.10.0 with mbedTLS or wolfSSL, TLS 1.3 cipher suites where set by using the CURLOPT_SSL_CIPHER_LIST(3) option.

Added in curl 7.61.0

Returns CURLE_OK if supported, CURLE_NOT_BUILT_IN otherwise.

CURLOPT_PROXY_SSLVERSION(3), CURLOPT_PROXY_SSL_CIPHER_LIST(3), CURLOPT_PROXY_TLS13_CIPHERS(3), CURLOPT_SSLVERSION(3), CURLOPT_SSL_CIPHER_LIST(3), CURLOPT_USE_SSL(3)

curl_easy_setopt(3), CURLOPT_PROXY_SSL_CIPHER_LIST(3), CURLOPT_PROXY_TLS13_CIPHERS(3), CURLOPT_SSL_CIPHER_LIST(3), CURLOPT_SSL_EC_CURVES(3), libcurl-symbols(3), nbdkit-curl-plugin(1).