PHP md5() Function
Example
Calculate the MD5 hash of the string "Hello":
<?php
$str = "Hello";
echo md5($str);
?>
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Definition and Usage
The md5() function calculates the MD5 hash of a string.
The md5() 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."
To calculate the MD5 hash of a file, use the md5_file() function.
Syntax
md5(string,raw)
Parameter Values
| Parameter | Description |
|---|---|
| string | Required. The string to be calculated |
| raw | Optional. Specifies hex or binary output format:
|
Technical Details
| Return Value: | Returns the calculated MD5 hash on success, or FALSE on failure |
|---|---|
| PHP Version: | 4+ |
| Changelog: | The raw parameter became optional in PHP 5.0 |
More Examples
Example
Print the result of md5():
<?php
$str = "Hello";
echo "The string: ".$str."<br>";
echo "TRUE - Raw 16 character binary format: ".md5($str, TRUE)."<br>";
echo "FALSE - 32 character hex number: ".md5($str)."<br>";
?>
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Example
Print the result of md5() and then test it:
<?php
$str = "Hello";
echo md5($str);
if (md5($str) == "8b1a9953c4611296a827abf8c47804d7")
{
echo "<br>Hello world!";
exit;
}
?>
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❮ PHP String Reference