curl/docs/libcurl/opts/CURLOPT_SSL_CIPHER_LIST.md

c	SPDX-License-Identifier	Title	Section	Source	See-also	Protocol	TLS-backend	Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	CURLOPT_SSL_CIPHER_LIST	3	libcurl	CURLOPT_PROXY_SSL_CIPHER_LIST (3) CURLOPT_PROXY_TLS13_CIPHERS (3) CURLOPT_SSLVERSION (3) CURLOPT_TLS13_CIPHERS (3) CURLOPT_USE_SSL (3)	TLS	OpenSSL BearSSL Schannel Secure Transport wolfSSL mbedTLS rustls	7.9

NAME

CURLOPT_SSL_CIPHER_LIST - ciphers to use for TLS

SYNOPSIS

#include <curl/curl.h>

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

DESCRIPTION

Pass a char pointer, pointing to a null-terminated string holding the list of cipher suites to use for the TLS 1.2 (1.1, 1.0) connection. The list must be syntactically correct, it consists of one or more cipher suite strings separated by colons.

For setting TLS 1.3 ciphers see CURLOPT_TLS13_CIPHERS(3).

A valid example of a cipher list is:

"ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:"
"ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305"

For Schannel, you can use this option to set algorithms but not specific cipher suites. Refer to the ciphers lists document for algorithms.

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.

DEFAULT

NULL, use built-in list

%PROTOCOLS%

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_CIPHER_LIST,
                     "ECDHE-ECDSA-CHACHA20-POLY1305:"
                     "ECDHE-RSA-CHACHA20-POLY1305");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

HISTORY

OpenSSL support added in 7.9. wolfSSL support added in 7.53.0. Schannel support added in 7.61.0. Secure Transport support added in 7.77.0. BearSSL support added in 7.83.0. mbedTLS support added in 8.8.0. rustls support added in 8.10.0.

Since curl 8.10.0 returns CURLE_NOT_BUILT_IN when not supported.

%AVAILABILITY%

RETURN VALUE

Returns CURLE_OK if supported, CURLE_NOT_BUILT_IN otherwise.