---
name: "Digest::HMAC"
section: "3pm"
platform: "linux"
package: "perl-digest-hmac"
version: "1.05-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Digest::HMAC"
---

# Digest::HMAC(3pm)

Keyed-Hashing for Message Authentication

## NAME

Digest::HMAC - Keyed-Hashing for Message Authentication

## SYNOPSIS

```
 # Functional style
 use Digest::HMAC qw(hmac hmac_hex);
 $digest = hmac($data, $key, \&myhash);
 print hmac_hex($data, $key, \&myhash);
 # OO style
 use Digest::HMAC;
 $hmac = Digest::HMAC->new($key, "Digest::MyHash");
 $hmac->add($data);
 $hmac->addfile(*FILE);
 $digest = $hmac->digest;
 $digest = $hmac->hexdigest;
 $digest = $hmac->b64digest;
```

## DESCRIPTION

HMAC is used for message integrity checks between two parties that share a secret key, and works in combination with some other Digest algorithm, usually MD5 or SHA-1.  The HMAC mechanism is described in RFC 2104.

HMAC follow the common `"Digest::"` interface, but the constructor takes the secret key and the name of some other simple `"Digest::"` as argument.

The **hmac()** and **hmac\_hex()** functions and the Digest::HMAC-\>**new()** constructor takes an optional `$blocksize` argument as well.  The HMAC algorithm assumes the digester to hash by iterating a basic compression function on blocks of data and the `$blocksize` should match the byte-length of such blocks.

The default `$blocksize` is 64 which is suitable for the MD5 and SHA-1 digest functions.  For stronger algorithms the blocksize probably needs to be increased.

## SEE ALSO

Digest::HMAC\_MD5, Digest::HMAC\_SHA1

RFC 2104

## MAINTAINER

Andrew Rodland \<arodland@cpan.org\>

## ORIGINAL AUTHORS

Graham Barr \<gbarr@ti.com\>, Gisle Aas \<gisle@aas.no\>