Message-Digest Algorithm 5, commonly known as MD5 is a widely used cryptographic hash function that produces a 128-bit hash value.
It takes an input (message) of arbitrary length and produces a fixed-length output (hash) that serves as a digital fingerprint of the message, providing a way to verify data integrity and authenticity.
PHP md5_file() Function
The following shows the syntax of the md5_file() function in PHP.
md5_file(string $filename, bool $binary = false): string|false
The function accepts two main parameters:
filename- this defines the path to the filename whose MD5 hash you wish to calculate.binary- A Boolean value that determines whether the MD5 digest is returned in raw binary format with a length of 16.
The function will calculate the md5 hash of the specified file and return the value as string output. The md5 has is a 32-character hexadecimal value.
Examples
The following examples demonstrates how to use the md5_file() function in PHP.
Example 1
The following will return the md5 digest value of the .bashrc file.
<?php
$filename = '.bashrc';
if (file_exists($filename)) {
$hash = md5_file($filename);
echo "MD5 hash of $filename: $hash";
} else {
echo "File not found: $filename";
}
?>
The code should calculate the MD5 hash of the provided file and return the value as:
MD5 hash of /home/d3b1an/.bashrc: ee35a240758f374832e809ae0ea4883a
If you make changes to the .bashrc file and calculate the md5 hash file, you should get a different value indicating the file has been modified.
Conclusion
In the tutorial, you learned how to use the PHP md5_file() file to calculate the MD5 digest of an input value allowing you to verify the integrity of a file.
