CURLOPT_SSL_CIPHER_LIST(3)

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 ciphers to use for the SSL connection. The list must be syntactically correct, it consists of one or more cipher strings separated by colons. Commas or spaces are also acceptable separators but colons are normally used, !, - and + can be used as operators.

For OpenSSL and GnuTLS valid examples of cipher lists include RC4-SHA, SHA1+DES, TLSv1 and DEFAULT. The default list is normally set when you compile OpenSSL.

For WolfSSL, valid examples of cipher lists include ECDHE-RSA-RC4-SHA, AES256-SHA:AES256-SHA256, etc.

For BearSSL, valid examples of cipher lists include ECDHE-RSA-CHACHA20-POLY1305:ECDHE-RSA-AES128-GCM-SHA256, or when using IANA names TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256:TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, etc. With BearSSL you do not add/remove ciphers. If one uses this option then all known ciphers are disabled and only those passed in are enabled.

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 internal default

PROTOCOLS
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

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, "TLSv1");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

AVAILABILITY
Added in 7.9, in 7.83.0 for BearSSL

If built TLS enabled.

RETURN VALUE
Returns CURLE_OK if TLS is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.

SEE ALSO
CURLOPT_PROXY_SSL_CIPHER_LIST(3), CURLOPT_PROXY_TLS13_CIPHERS(3), CURLOPT_SSLVERSION(3), CURLOPT_TLS13_CIPHERS(3), CURLOPT_USE_SSL(3)