PHP String md5_file() Function

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The PHP String md5_file() function is used to calculates the md5 hash of a given file. It basically determines the MD5 hash of the file provided by the filename parameter using the "RSA Data Security, Inc. MD5 Message-Digest Algorithm," and then returns the hash. The hash is a 32-character hexadecimal number.

Syntax

Below is the syntax of the PHP String md5_file() function −

string md5_file ( string $filename, bool $binary = false )

Parameters

Here are the parameters of the md5_file() function −

• $filename − It contains the information about filename.

• $binary − When it is set to TRUE, returns the digest in raw binary format with a length of 16.

Return Value

The md5_file() function returns the string on success and FALSE on failure.

PHP Version

First introduced in core PHP 4.2.0, the md5_file() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

First we will show you the basic example of the PHP String md5_file() function to calculate the MD5 hash of a file and prints it in a readable hexadecimal format.

<?php
   // File whose hash needs to be calculated
   $file = '/PHP/PhpProjects/myfile.txt';

   // Calculate the MD5 hash
   $hash = md5_file($file);

   if ($hash !== false) {
      echo "MD5 hash of the file is: $hash\n";
   } else {
      echo "Failed to calculate hash. File might not exist.\n";
   }
?>

Output

Here is the outcome of the following code −

MD5 hash of the file is: de45556bf39e8e14e3bcd4f365d5022b

Example 2

In the below PHP program we will compare a file's current MD5 hash with a known hash to verify its integrity and show the usage of md5_file() function.

<?php
   // File to verify
   $file = '/PHP/PhpProjects/myfile.txt';

   // Known hash for comparison
   $knownHash = "5d41402abc4b2a76b9719d911017c592"; 

   // Calculate the file's current hash
   $currentHash = md5_file($file);

   if ($currentHash !== false) {
      if ($currentHash === $knownHash) {
         echo "File integrity verified. Hash matches!\n";
      } else {
         echo "File integrity check failed. Hash does not match.\n";
      }
   } else {
      echo "Failed to calculate hash. File might not exist.\n";
   }
?> 

Output

This will generate the below output −

File integrity check failed. Hash does not match.

Example 3

Now the below code calculates a file's MD5 hash and saves the result to another file for keeping the record.

<?php
   // File to hash
   $file = '/PHP/PhpProjects/myfile.txt';

   // Output file for the hash
   $outputFile = '/PHP/PhpProjects/hash_record.txt';

   // Calculate the MD5 hash
   $hash = md5_file($file);

   if ($hash !== false) {
      file_put_contents($outputFile, $hash);
      echo "Hash saved to $outputFile\n";
   } else {
      echo "Failed to calculate hash. File might not exist.\n";
   }
?> 

Output

This will create the below output −

Hash saved to /PHP/PhpProjects/hash_record.txt

Example 4

This program calculates the MD5 hash of a file with the help of md5_file() function and results it in raw binary format.

<?php
   // File to hash
   $file = '/Users/nikitashashrivastava/Desktop/My Docs/PHP/PhpProjects/myfile.txt';

   // Calculate the binary format MD5 hash
   $hash = md5_file($file, true);

   if ($hash !== false) {
      echo "Binary MD5 hash: " . bin2hex($hash) . "\n"; // Convert binary to readable format for display
   } else {
      echo "Failed to calculate hash. File might not exist.\n";
   }
?> 

Output

Following is the output of the above code −

Binary MD5 hash: de45556bf39e8e14e3bcd4f365d5022b