---
name: "crypto_aead_authsize"
section: "9"
platform: "linux"
package: "linux-manual-4.9"
version: "4.9.228-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/crypto_aead_authsize"
---

# crypto\_aead\_authsize(9)

obtain maximum authentication data size

## NAME

crypto\_aead\_authsize - obtain maximum authentication data size

## SYNOPSIS

**unsigned int crypto\_aead\_authsize(struct crypto\_aead \*** *tfm***);**

## ARGUMENTS

*tfm*

cipher handle

## DESCRIPTION

The maximum size of the authentication data for the AEAD cipher referenced by the AEAD cipher handle is returned. The authentication data size may be zero if the cipher implements a hard-coded maximum.

The authentication data may also be known as “tag value”.

## RETURN

authentication data size / tag size in bytes

## AUTHORS

**Stephan Mueller** \<smueller@chronox.de\>

Author.

**Marek Vasut** \<marek@denx.de\>

Author.

## COPYRIGHT