PHP | hash_hmac_file() Function

PHP hash_hmac_file() Function


Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP hash_hmac_file() Function.

The built-in PHP hash_hmac_file() function is used in generating keyed hash value for the given file content making use of HMAC method.

HMAC is an acronym which stands for keyed-hash message authentication code or hash-based message authentication code. It makes use of cryptographic hash function like md5, sha-256 and a secret key to hash the file contents given.

Syntax

Following below is the syntax to use this function -

hash_hmac_file ( 
   string $algo , string $filename , string $key [, bool $raw_output = FALSE ] 
) 
: string


Parameter Details

Sr.NoParameter & Description
1

algo

Name of the hashing algorithm. There is a big list of algorithm available with hash, some important ones are md5, sha256, etc.

To get the full list of algorithms supported, check for hash_hmac_algos()

2

filename

The filepath to get the file contents.

3

key

Secret key to generate HMAC variant of the message digest.

4

raw_output

By default the value is false and hence it returns lowercase hexits values. If the value is true, it will return raw binary data.


Return Value

This built-in PHP function returns a strings of calculated message digest that will be in the form of lowercase hexits if raw_output is false, otherwise it will return raw binary data.

PHP Version

This built-in PHP function works from PHP version greater than 5.1.2.

Example1

The following example below demonstrates the usage of hash_hmac_file() function -

<?php
   file_put_contents('file2.txt', 'Welcome to Webdesigntutorialz');
   echo hash_hmac_file('md5', 'file2.txt', 'anysecretkey');
?>

Output

When the above code is executed, it will produce the following result -

e9768f4407dcb22fb99cb6c4449f1067

Example2

The example below shows the difference in the PHP hash_hmac_file() output when the file contents are changed -

<?php
   file_put_contents('abc.txt', 'Hello'); 
   echo hash_hmac_file('sha256', 'abc.txt', 'mysecretkey'); 
   echo "<br/><br/>";
   file_put_contents('abc.txt', 'World');
   echo hash_hmac_file('md5', 'abc.txt', 'anysecretkey'); 
?>

Output

When the above code is executed, it will produce the following result -

362a60a6ef4e35f9559304a6b5372b070c97ba33cb4a747503c9c58b5c85e6db2652fb7ccf4cff91df4f08add44b93b2

Example3

The example below shows the difference in hash_file() and hash_hmac_file() output -

<?php
   file_put_contents('filetest.txt', 'Welcome to Webdesigntutorialz');
   echo hash_file('sha256', 'filetest.txt');
   echo "<br/><br/>";
   file_put_contents('abc.txt', 'Welcome to Webdesigntutorialz'); 
   echo hash_hmac_file('sha256', 'abc.txt', 'mysecretkey'); 
?>

Output

When the above code is executed, it will produce the following result -

b952e8666ddb57f4b80a70041a9bc151166dd11d4aaf1393c243cf720841be77<br/><br/>b6f6f03642e61cc076d4e2def5db4048c4bb2be8308a76190e346831a6301508


Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial guide, we are going to be discussing about the PHP hash_pbkdf2() Function.

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