---
name: "gnutls_x509_crt_check_key_purpose"
section: "3"
platform: "linux"
package: "gnutls"
version: "3.8.13-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/gnutls_x509_crt_check_key_purpose"
---

# gnutls\_x509\_crt\_check\_key\_purpose(3)

API function

## NAME

gnutls\_x509\_crt\_check\_key\_purpose - API function

## SYNOPSIS

**#include \<gnutls/x509.h\>**

**unsigned gnutls\_x509\_crt\_check\_key\_purpose(gnutls\_x509\_crt\_t** *cert***, const char \*** *purpose***, unsigned** *flags***);**

## ARGUMENTS

- gnutls\_x509\_crt\_t cert

  should contain a **gnutls\_x509\_crt\_t** type

- const char \* purpose

  a key purpose OID (e.g., **GNUTLS\_KP\_CODE\_SIGNING**)

- unsigned flags

  zero or **GNUTLS\_KP\_FLAG\_DISALLOW\_ANY**

## DESCRIPTION

This function will check whether the given certificate matches the provided key purpose. If  *flags* contains **GNUTLS\_KP\_FLAG\_ALLOW\_ANY** then it a certificate marked for any purpose will not match.

## RETURNS

zero if the key purpose doesn't match, and non-zero otherwise.

## SINCE

3\.5.6

## REPORTING BUGS

Report bugs to \<bugs@gnutls.org\>.\
 Home page: https://www.gnutls.org

## COPYRIGHT

Copyright © 2001-2023 Free Software Foundation, Inc., and others.\
 Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

## SEE ALSO

The full documentation for **gnutls** is maintained as a Texinfo manual. If the /usr/share/doc/gnutls/ directory does not contain the HTML form visit

- https://www.gnutls.org/manual/