php man page for md5

MD5(3)									 1								    MD5(3)

md5 - Calculate the md5 hash of a string

SYNOPSIS
       string md5 (string  $str, [bool	$raw_output = false])

DESCRIPTION
	Calculates the MD5 hash of $str using the RSA Data Security, Inc. MD5 Message-Digest Algorithm, and returns that hash.

PARAMETERS
	      o $str
		- The string.

	      o $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(3) example

	      <?php
	      $str = 'apple';

	      if (md5($str) === '1f3870be274f6c49b3e31a0c6728957f') {
		  echo "Would you like a green or red apple?";
	      }
	      ?>

NOTES
       Note

	      Secure password hashing

	       It  is  not  recommended  to  use this function to secure passwords, due to the fast nature of this hashing algorithm. See here for
	      details.

SEE ALSO
       md5_file(3), sha1_file(3), crc32(3), sha1(3), hash(3), crypt(3), password_hash(3).

PHP Documentation Group 														    MD5(3)