NAME

       CURLOPT_SSL_SIGNATURE_ALGORITHMS - signature algorithms to use for TLS

SYNOPSIS

       #include <curl/curl.h>

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

DESCRIPTION

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

       A valid example of a signature algorithms list with OpenSSL is:
       "DSA+SHA256:rsa_pss_pss_sha256"

       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
       disable its use again.

       Works with OpenSSL and its BoringSSL fork (added in 8.14.0).

DEFAULT

       NULL, use built-in list

PROTOCOLS

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

       This option works only with the following TLS backends: OpenSSL

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_SIGNATURE_ALGORITHMS,
                            "DSA+SHA256:rsa_pss_pss_sha256");
           res = curl_easy_perform(curl);
           curl_easy_cleanup(curl);
         }
       }

HISTORY

       OpenSSL support added in 8.14.0.

AVAILABILITY

       Added in curl 8.14.0

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_SSLVERSION(3), CURLOPT_SSL_CIPHER_LIST(3), CURLOPT_SSL_EC_CURVES(3), CURLOPT_USE_SSL(3)

libcurl                                            2025-06-16                CURLOPT_SSL_SIGNATURE_ALGORITHMS(3)