PHP calculates the MD5 hash function md5_file() of a file

Example

Calculate the MD5 hash of the text file "test.txt":

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

The above code will output:

d41d8cd98f00b204e9800998ecf8427e

Definition and usage

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

The md5_file() function uses RSA data security, including the MD5 message digest algorithm.

Explanation from RFC 1321 - MD5 message digest algorithm: The MD5 message digest algorithm takes information of any length as an input value and converts it into a 128-bit length "fingerprint information" or "message" Summary" value to represent this input value, and the converted value as the result. The MD5 algorithm is primarily designed for digital signature applications where larger files are encrypted using a public key in a cryptographic system such as RSA. (done by setting a private key) before compressing in a secure manner.

To calculate the MD5 hash of a string, use the md5() function.

Syntax

md5_file(file,raw)

Parameters Description

##PHP Version: 4.2.0+

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

<?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 file is ok.

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