CURLOPT_TLSAUTH_USERNAME

CURLOPT_TLSAUTH_USERNAME is one of the accepted parameters for curl_setopt parameter #2.

CURLOPT_TLSAUTH_USERNAME — Set a string with the username to use for the TLS authentication method specified with the CURLOPT_TLSAUTH_TYPE option. Requires that the CURLOPT_TLSAUTH_PASSWORD option also be set. This feature relies on TLS SRP which does not work with TLS 1.3. Available as of cURL 7.21.4.

CURLOPT_TLSAUTH_USERNAME = 10204;