Section: curl_easy_setopt options (3)
Updated: June 25, 2020
CURLOPT_SSL_CIPHER_LIST - specify ciphers to use for TLS
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_CIPHER_LIST, char *list);
Pass a char *, 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
You'll find more details about cipher lists on this URL:
For NSS, valid examples of cipher lists include 'rsa_rc4_128_md5',
'rsa_aes_128_sha', etc. With NSS you don't add/remove ciphers. If one uses
this option then all known ciphers are disabled and only those passed in are
For WolfSSL, valid examples of cipher lists include
'ECDHE-RSA-RC4-SHA', 'AES256-SHA:AES256-SHA256', etc.
The application does not have to keep the string around after setting this
NULL, use internal default
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_SSL_CIPHER_LIST, "TLSv1");
ret = curl_easy_perform(curl);
If built TLS enabled.
Returns CURLE_OK if TLS is supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.