---
name: "gnutls_hmac_get_key_size"
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_hmac_get_key_size"
---

# gnutls\_hmac\_get\_key\_size(3)

API function

## NAME

gnutls\_hmac\_get\_key\_size - API function

## SYNOPSIS

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

**unsigned gnutls\_hmac\_get\_key\_size(gnutls\_mac\_algorithm\_t** *algorithm***);**

## ARGUMENTS

- gnutls\_mac\_algorithm\_t algorithm

  the mac algorithm to use

## DESCRIPTION

This function will return the size of the key to be used with this algorithm. On the algorithms which may accept arbitrary key sizes, the returned size is the MAC key size used in the TLS protocol.

## RETURNS

The key size or zero on error.

## SINCE

3\.6.12

## 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/