---
name: "gnutls_crypto_register_mac"
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_crypto_register_mac"
---

# gnutls\_crypto\_register\_mac(3)

API function

## NAME

gnutls\_crypto\_register\_mac - API function

## SYNOPSIS

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

**int gnutls\_crypto\_register\_mac(gnutls\_mac\_algorithm\_t** *algorithm***, int** *priority***, gnutls\_mac\_init\_func** *init***, gnutls\_mac\_setkey\_func** *setkey***, gnutls\_mac\_setnonce\_func** *setnonce***, gnutls\_mac\_hash\_func** *hash***, gnutls\_mac\_output\_func** *output***, gnutls\_mac\_deinit\_func** *deinit***, gnutls\_mac\_fast\_func** *hash\_fast***);**

## ARGUMENTS

- gnutls\_mac\_algorithm\_t algorithm

  is the gnutls MAC identifier

- int priority

  is the priority of the algorithm

- gnutls\_mac\_init\_func init

  A function which initializes the MAC

- gnutls\_mac\_setkey\_func setkey

  A function which sets the key of the MAC

- gnutls\_mac\_setnonce\_func setnonce

  A function which sets the nonce for the mac (may be **NULL** for common MAC algorithms)

- gnutls\_mac\_hash\_func hash

  Perform the hash operation

- gnutls\_mac\_output\_func output

  Provide the output of the MAC

- gnutls\_mac\_deinit\_func deinit

  A function which deinitializes the MAC

- gnutls\_mac\_fast\_func hash\_fast

  Perform the MAC operation in one go

## DESCRIPTION

This function will register a MAC algorithm to be used by gnutls. Any algorithm registered will override the included algorithms and by convention kernel implemented algorithms have priority of 90 and CPU-assisted of 80. The algorithm with the lowest priority will be used by gnutls.

## DEPRECATED

since 3.7.0 it is no longer possible to override cipher implementation

## RETURNS

**GNUTLS\_E\_SUCCESS** on success, otherwise a negative error code.

## SINCE

3\.4.0

## 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/