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PHP md5_file() Function

PHP String Reference Complete PHP String Reference

Definition and Usage

The md5_file() function calculates the MD5 hash of a file.

The md5_file() function uses the RSA Data Security, Inc. MD5 Message-Digest Algorithm.

From RFC 1321 - The MD5 Message-Digest Algorithm: "The MD5 message-digest algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA."

This function returns the calculated MD5 hash on success, or FALSE on failure.

Syntax

md5_file(file,raw)

Parameter Description
file Required. The file to be calculated
raw Optional. Specifies hex or binary output format:
  • TRUE - Raw 16 character binary format
  • FALSE - Default. 32 character hex number

Note: This parameter was added in PHP 5.0

Example 1

<?php
$filename = "test.txt";
$md5file = md5_file($filename);
echo $md5file;
?>

The output of the code above will be:

5d41402abc4b2a76b9719d911017c592

Example 2

Store the MD5 hash of "test.txt" in a file:

<?php
$md5file = md5_file("test.txt");
file_put_contents("md5file.txt",$md5file);
?>

In this example we will test if "test.txt" has been changed (that is if the MD5 hash has been changed):

<?php
$md5file = file_get_contents("md5file.txt");
if (md5_file("test.txt") == $md5file)
  {
  echo "The file is ok.";
  }
else
  {
  echo "The file has been changed.";
  }
?>

The output of the code above could be:

The file is ok.

PHP String Reference Complete PHP String Reference
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