Description ¶
string md5 ( string $str [, bool $raw_output = FALSE ] )
Calculates the MD5 hash of str using the » RSA Data Security, Inc. MD5 Message-Digest Algorithm, and returns that hash.

Parameters ¶
str
The string.

raw_output
If the optional raw_output is set to TRUE, then the md5 digest is instead returned in raw binary format with a length of 16.

Return Values ¶
Returns the hash as a 32-character hexadecimal number.

Examples ¶
Example #1 A md5() example

<?php
$str = 'apple';

if (md5($str) === '1f3870be274f6c49b3e31a0c6728957f') {
    echo "Would you like a green or red apple?";
}
?>
See Also ¶
md5_file() - Calculates the md5 hash of a given file
sha1_file() - Calculate the sha1 hash of a file
crc32() - Calculates the crc32 polynomial of a string
sha1() - Calculate the sha1 hash of a string
hash() - Generate a hash value (message digest)
crypt() - One-way string hashing
password_hash() - Creates a password hash
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User Contributed Notes 13 notes
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10 radon8472 at radon-software dot net ¶2 years ago
<?php
    function raw2hex($rawBinaryChars)
    {
      return = array_pop(unpack('H*', $rawBinaryChars));
    }
?>

The complement of hey2raw.
You can use to convert from raw md5-format to human-readable format.

This can be usefull to check "Content-Md5" HTTP-Header.

<?php
  $rawMd5    = base64_decode($_SERVER['HTTP_CONTENT_MD5']);
  $post_data = file_get_contents("php://input");

  if(raw2hex($rawMd5) == md5($post_data)) // Post-Data is okay
  else                                    // Post-Data is currupted
?>
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3 Some ONE ¶11 months ago
speed of hash('md5',) VS md5()

2017-07-14, on a i7-3540M CPU @ 3.00GHz, md5() is slightly quicker than hash('md5',)
This code takes 2.29 seconds
<?php
for($i=0;$i<10000000;++$i) md5("$i");
?>

while this one takes 2.77 seconds
<?php
for($i=0;$i<10000000;++$i) hash('md5',"$i");
?>

But in average, less than half a second for 10 000 000 repetitions is a very minimal advantage.