Crypt::Mac::HMAC(3) User Contributed Perl Documentation Crypt::Mac::HMAC(3)
NAME
Crypt::Mac::HMAC - Message authentication code HMAC
SYNOPSIS
### Functional interface:
use Crypt::Mac::HMAC qw( hmac hmac_hex hmac_b64 hmac_b64u );
# calculate MAC from string/buffer
my $hmac_raw = hmac('SHA256', $key, 'data buffer');
my $hmac_hex = hmac_hex('SHA256', $key, 'data buffer');
my $hmac_b64 = hmac_b64('SHA256', $key, 'data buffer');
my $hmac_b64u = hmac_b64u('SHA256', $key, 'data buffer');
### OO interface:
use Crypt::Mac::HMAC;
my $d = Crypt::Mac::HMAC->new('SHA256', $key);
$d->add('any data');
my $result_hex = $d->hexmac; # finalizes the object
# for another output encoding use a fresh object (or clone before finalizing)
my $result_b64u = Crypt::Mac::HMAC->new('SHA256', $key)->add('any data')->b64umac;
# or MAC a file instead
my $file_result_raw = Crypt::Mac::HMAC->new('SHA256', $key)->addfile('filename.dat')->mac;
DESCRIPTION
Provides an interface to the HMAC message authentication code (MAC)
algorithm.
EXPORT
Nothing is exported by default.
You can export selected functions:
use Crypt::Mac::HMAC qw( hmac hmac_hex hmac_b64 hmac_b64u );
Or all of them at once:
use Crypt::Mac::HMAC ':all';
FUNCTIONS
hmac
Joins all arguments into a single string and returns its HMAC message
authentication code encoded as a binary string.
Data arguments for the functional helpers are converted to byte strings
using Perl's usual scalar stringification. Defined scalars, including
numbers and string-overloaded objects, are accepted. "undef" is treated
as an empty string and may emit Perl's usual "uninitialized value"
warning. The same rules apply to "hmac_hex", "hmac_b64", and
"hmac_b64u".
my $hmac_raw = hmac($hash_name, $key, 'data buffer');
#or
my $hmac_raw = hmac($hash_name, $key, 'any data', 'more data', 'even more data');
# $hash_name ... [string] any <NAME> for which there is a Crypt::Digest::<NAME> module
# $key ......... [binary string] the key (octets/bytes)
hmac_hex
Joins all arguments into a single string and returns its HMAC message
authentication code encoded as a hexadecimal string.
my $hmac_hex = hmac_hex($hash_name, $key, 'data buffer');
#or
my $hmac_hex = hmac_hex($hash_name, $key, 'any data', 'more data', 'even more data');
# $hash_name ... [string] any <NAME> for which there is a Crypt::Digest::<NAME> module
# $key ......... [binary string] the key (not hex!)
hmac_b64
Joins all arguments into a single string and returns its HMAC message
authentication code encoded as a Base64 string.
my $hmac_b64 = hmac_b64($hash_name, $key, 'data buffer');
#or
my $hmac_b64 = hmac_b64($hash_name, $key, 'any data', 'more data', 'even more data');
# $hash_name ... [string] any <NAME> for which there is a Crypt::Digest::<NAME> module
# $key ......... [binary string] the key (not Base64!)
hmac_b64u
Joins all arguments into a single string and returns its HMAC message
authentication code encoded as a Base64 URL-safe string (see RFC 4648
section 5).
my $hmac_b64url = hmac_b64u($hash_name, $key, 'data buffer');
#or
my $hmac_b64url = hmac_b64u($hash_name, $key, 'any data', 'more data', 'even more data');
# $hash_name ... [string] any <NAME> for which there is a Crypt::Digest::<NAME> module
# $key ......... [binary string] the key (not Base64url!)
METHODS
Unless noted otherwise, assume $d is an existing MAC object created via
"new", for example:
my $d = Crypt::Mac::HMAC->new('SHA256', $key);
new
my $d = Crypt::Mac::HMAC->new($hash_name, $key);
# $hash_name ... [string] one of 'SHA256', 'SHA384', 'SHA512', 'SHA1', 'SHA3_256', 'BLAKE2b_256',
# 'RIPEMD160', etc. - any <NAME> for which there is a Crypt::Digest::<NAME> module
# $key ......... [binary string] the key (any length - internally padded/hashed as per RFC 2104)
clone
$d->clone();
add
Appends data to the message. Returns the object itself (for chaining).
Croaks if the object has already been finalized by "mac", "hexmac",
"b64mac", or "b64umac".
Each argument is converted to bytes using Perl's usual scalar
stringification. Defined scalars, including numbers and
string-overloaded objects, are accepted. "undef" is treated as an empty
string and may emit Perl's usual "uninitialized value" warning.
$d->add('any data');
#or
$d->add('any data', 'more data', 'even more data');
addfile
Reads the file content and appends it to the message. Returns the
object itself (for chaining). Croaks if the object has already been
finalized by "mac", "hexmac", "b64mac", or "b64umac".
$d->addfile('filename.dat');
#or
my $filehandle = ...; # existing binary-mode filehandle
$d->addfile($filehandle);
mac
Returns the binary MAC (raw bytes) and finalizes the object. After the
first call to "mac", "hexmac", "b64mac", or "b64umac", later calls to
"add", "addfile", or any MAC getter croak.
my $result_raw = $d->mac();
hexmac
Returns the MAC encoded as a lowercase hexadecimal string and finalizes
the object. After the first call to "mac", "hexmac", "b64mac", or
"b64umac", later calls to "add", "addfile", or any MAC getter croak.
my $result_hex = $d->hexmac();
b64mac
Returns the MAC encoded as a Base64 string with trailing "=" padding
and finalizes the object. After the first call to "mac", "hexmac",
"b64mac", or "b64umac", later calls to "add", "addfile", or any MAC
getter croak.
my $result_b64 = $d->b64mac();
b64umac
Returns the MAC encoded as a Base64 URL-safe string (no trailing "=")
and finalizes the object. After the first call to "mac", "hexmac",
"b64mac", or "b64umac", later calls to "add", "addfile", or any MAC
getter croak.
my $result_b64url = $d->b64umac();
SEE ALSO
o CryptX(3)
o <https://en.wikipedia.org/wiki/Hmac>
o <https://www.rfc-editor.org/rfc/rfc2104>
perl v5.34.3 2026-05-11 Crypt::Mac::HMAC(3)
cryptx 0.89.0 - Generated Tue May 12 07:13:04 CDT 2026