---
name: "gnutls_openpgp_crt_get_subkey_usage"
section: "3"
platform: "linux"
package: "gnutls-doc"
version: "3.5.8-5+deb9u5"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/gnutls_openpgp_crt_get_subkey_usage"
---

# gnutls\_openpgp\_crt\_get\_subkey\_usage(3)

API function

## NAME

gnutls\_openpgp\_crt\_get\_subkey\_usage - API function

## SYNOPSIS

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

**int gnutls\_openpgp\_crt\_get\_subkey\_usage(gnutls\_openpgp\_crt\_t** *key***, unsigned int** *idx***, unsigned int \*** *key\_usage***);**

## ARGUMENTS

- gnutls\_openpgp\_crt\_t key

  should contain a gnutls\_openpgp\_crt\_t type

- unsigned int idx

  the subkey index

- unsigned int \* key\_usage

  where the key usage bits will be stored

## DESCRIPTION

This function will return certificate's key usage, by checking the key algorithm.  The key usage value will ORed values of **GNUTLS\_KEY\_DIGITAL\_SIGNATURE** or **GNUTLS\_KEY\_KEY\_ENCIPHERMENT**.

A negative error code may be returned in case of parsing error.

## RETURNS

key usage value.

## SINCE

2\.4.0

## REPORTING BUGS

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

## COPYRIGHT

Copyright © 2001-2020 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

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