---
name: "gnutls_x509_ext_export_key_usage"
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_ext_export_key_usage"
---

# gnutls\_x509\_ext\_export\_key\_usage(3)

API function

## NAME

gnutls\_x509\_ext\_export\_key\_usage - API function

## SYNOPSIS

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

**int gnutls\_x509\_ext\_export\_key\_usage(unsigned int** *usage***, gnutls\_datum\_t \*** *ext***);**

## ARGUMENTS

- unsigned int usage

  an ORed sequence of the GNUTLS\_KEY\_\* elements.

- gnutls\_datum\_t \* ext

  The DER-encoded extension data; must be freed using **gnutls\_free()**.

## DESCRIPTION

This function will convert the keyUsage bit string to a DER encoded PKIX extension. The  *ext* data will be allocated using **gnutls\_malloc()**.

## RETURNS

On success, **GNUTLS\_E\_SUCCESS** (0) is returned, otherwise a negative error value.

## SINCE

3\.3.0

## 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/