---
name: "CURLOPT_TLSAUTH_TYPE"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_TLSAUTH_TYPE"
---

# CURLOPT\_TLSAUTH\_TYPE(3)

TLS authentication methods

## NAME

CURLOPT\_TLSAUTH\_TYPE - TLS authentication methods

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TLSAUTH_TYPE, char *type);
```

## DESCRIPTION

Deprecated option. It serves no purpose anymore.

Pass a pointer to a null-terminated string as parameter. The string should be the method of the TLS authentication. Supported method is "SRP".

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to restore to internal default.

The application does not have to keep the string around after setting this option.

- SRP

  TLS-SRP authentication. Secure Remote Password authentication for TLS is defined in RFC 5054 and provides mutual authentication if both sides have a shared secret. To use TLS-SRP, you must also set the *[CURLOPT\_TLSAUTH\_USERNAME(3)](/CURLOPT_TLSAUTH_USERNAME/3.md)* and *[CURLOPT\_TLSAUTH\_PASSWORD(3)](/CURLOPT_TLSAUTH_PASSWORD/3.md)* options.

  TLS-SRP does not work with TLS 1.3.

## DEFAULT

blank

## DEPRECATED

This option was deprecated in 8.22.0.

## PROTOCOLS

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

This option works only with the following TLS backends: GnuTLS and OpenSSL

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_TLSAUTH_TYPE, "SRP");
    curl_easy_setopt(curl, CURLOPT_TLSAUTH_USERNAME, "user");
    curl_easy_setopt(curl, CURLOPT_TLSAUTH_PASSWORD, "secret");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in curl 7.21.4

## RETURN VALUE

*[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*.

## SEE ALSO

[**CURLOPT\_TLSAUTH\_PASSWORD**(3)](/CURLOPT_TLSAUTH_PASSWORD/3.md), [**CURLOPT\_TLSAUTH\_USERNAME**(3)](/CURLOPT_TLSAUTH_USERNAME/3.md)