PHP 7.0.6 Released

    md5

    (PHP 4, PHP 5, PHP 7)

    md5 — Calculate the md5 hash of a string

    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?";
    }
    ?>

    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() - 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

    User Contributed Notes

    Shane Allen
    13 years ago
    From the documentation on Digest::MD5:
    md5($data,...)
    This function will concatenate all arguments, calculate the MD5 digest of this "message", and return it in binary form.

    md5_hex($data,...)
    Same as md5(), but will return the digest in hexadecimal form.

    PHP's function returns the digest in hexadecimal form, so my guess is that you're using md5() instead of md5_hex(). I have verified that md5_hex() generates the same string as PHP's md5() function.

    (original comment snipped in various places)
    >Hexidecimal hashes generated with Perl's Digest::MD5 module WILL
    >NOT equal hashes generated with php's md5() function if the input
    >text contains any non-alphanumeric characters.
    >
    >$phphash = md5('pa$$');
    >echo "php original hash from text: $phphash";
    >echo "md5 hash from perl: " . $myrow['password'];
    >
    >outputs:
    >
    >php original hash from text: 0aed5d740d7fab4201e885019a36eace
    >hash from perl: c18c9c57cb3658a50de06491a70b75cd
    sebastian dot haller at freesurf dot ch
    9 years ago
    It has been found, that hash('md5', 'string'); is faster than md5($string):

    http://www.php.net/manual/en/function.hash.php
    admin at gadelkareem dot com
    8 years ago
    MySQL MD() will not give you the same hash if character set is different.
    ex :
    <?php
    #suppose table_name CHARSET=UTF8
    #$md5 = md5('Städte'); # will give you a different hash than MySQL MD5()
    #instead use
    $md5 = md5(utf8_encode('Städte'));
    $r = mysql_query("SELECT *, MD5(`word`) FROM `table_name` WHERE MD5(`word`) LIKE '{$md5}'");
    if(    $r)
        while(     $row= mysql_fetch_assoc($r) )
                print_r($row);

    ?>
    rahul dot giri64 at gmail dot com
    2 years ago
    Requested to every php programmer ,  never ever ever  use md5() to  encrypt your passwords. it's not safe.

    Go for either one of this -

    1)  SHA-1
    2)   SHA-2(SHA-256 , SHA-512)
    3) Whirlpool
    4) Tiger
    5) AES
    6)blowfish (recommended 'it's , secure, free and easy)

    I wish you safe internet life , thanks  :)
    radon8472 at radon-software dot net
    13 days 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
    ?>
    dionyziz at deviantart dot com
    8 years ago
    Sometimes it's useful to get the actual, binary, md5 digest.
    You can use this function for it:

    <?php

    function md5bin( $target ) {
            $md5 = md5( $target );
            $ret = '';

        for (     $i = 0; $i < 32; $i += 2 ) {
                $ret .= chr( hexdec( $md5{ $i + 1 } ) + hexdec( $md5{ $i } ) * 16 );
        }

        return     $ret;
    }

    ?>
    terry _at_ scribendi_com
    11 years ago
    Do not use the hex strings returned by md5() as a key for MCrypt 256-bit encryption.  Hex characters only represent four bits each, so when you take 32 hex characters, you are only really using a 128-bit key, not a 256-bit one. 

    Using an alphanumeric key generator [A-Za-z0-9] will also only provide a 192-bit key in 32 characters.

    Two different MD5s concatenated in raw binary form, or mcrypt_create_iv(32,MCRYPT_DEV_RANDOM) will give you a true 256-bit key string.
    John
    6 years ago
    If you want to hash a large amount of data you can use the hash_init/hash_update/hash_final functions.

    This allows you to hash chunks/parts/incremental or whatever you like to call it.
    programings at abv dot bg
    2 years ago
    This recursive function allow you to hash something in depth using md5().

    <?php
    function checksum($what, $depth = 1) {
    $depth--;
    if (!    $depth)
    return     md5($what);
    else
    return     md5(checksum($what, $depth));
    }
    ?>

    The function hashed the previous hash to md5() again and again for number of times and returns the last received hash.

    Example usage:

    <?php
    for ($i = 1; $i <= 10; $i++) {
    echo     "$i. ".checksum("test", $i)."<br />";
    }
    ?>

    It can be used for security purposes.
    John S.
    11 years ago
    If you want to replicate CPAN Digest::MD5's function md5_base64 in PHP, use this code:

    <?php

    function md5_base64 ( $data )
    {
        return     preg_replace('/=+$/','',base64_encode(pack('H*',md5($data))));
    }

    ?>
    Anonymous
    4 years ago
    This is not encryption..... it's only a sort of DIGEST
    rahul dot giri64 at gmail dot com
    2 years ago
    Requested to every php programmer ,  never ever ever  use md5() to  encrypt your passwords. it's not safe.

    Go for either one of them -

    1)  SHA-1
    2)   SHA-2(SHA-256 , SHA-512)
    3) Whirlpool
    4) Tiger
    5) AES
    6)blowfish (recommended 'it's , secure, free and easy)

    I wish you safe internet life , thanks  :)
    marzetti dot marco at NOSPAM dot gmail dot com
    9 years ago
    The complement of raw2hex

    <?php

    function hex2raw( $str ){
          $chunks = str_split($str, 2);
      for(     $i = 0; $i < sizeof($chunks); $i++ ) {
                $op .= chr( hexdec( $chunks[$i] ) );
        }
        return     $op;
    }

    ?>
    rafael59
    2 years ago
    <?php
    $str     = "string";
    echo     md5($str);
    ?>
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