CURLOPT_SSL_SIGNATURE_ALGORITHMS(3)                   Library Functions Manual

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                           2025-06-04
                                           CURLOPT_SSL_SIGNATURE_ALGORITHMS(3)