md5

(PHP 4, PHP 5, PHP 7)

md5Возвращает MD5-хеш строки

Внимание

Не рекомендуется использовать эту функцию для обеспечения безопасности хранения паролей ввиду высокой скорости работы данного алгоритма. Более подробно читайте в разделе Ответы на часто задаваемые вопросы по хешированию паролей.

Описание

md5 ( string $str [, bool $raw_output = FALSE ] ) : string

Вычисляет MD5-хеш строки str, используя » алгоритм MD5 RSA Data Security, Inc. и возвращает этот хеш.

Список параметров

str

Строка.

raw_output

Если необязательный аргумент raw_output имеет значение TRUE, то возвращается бинарная строка из 16 символов.

Возвращаемые значения

Возвращает хеш в виде 32-символьного шестнадцатеричного числа.

Примеры

Пример #1 Пример использования md5()

<?php
$str 
'яблоко';

if (
md5($str) === '1afa148eb41f2e7103f21410bf48346c') {
    echo 
"Вам зеленое или красное яблоко?";
}
?>

Смотрите также

  • md5_file() - Возвращает MD5-хеш файла
  • sha1_file() - Возвращает SHA1-хеш файла
  • crc32() - Вычисляет полином CRC32 для строки
  • sha1() - Возвращает SHA1-хеш строки
  • hash() - Генерирует хеш-код (дайджест сообщения)
  • crypt() - Необратимое хеширование строки
  • password_hash() - Создает хеш пароля

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User Contributed Notes 8 notes

up
7
Ray.Paseur sometimes uses Gmail
1 year ago
md5('240610708') == md5('QNKCDZO')

This comparison is true because both md5() hashes start '0e' so PHP type juggling understands these strings to be scientific notation.  By definition, zero raised to any power is zero.
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13
John
10 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.
up
0
radon8472 at radon-software dot net
4 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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-7
Shane Allen
17 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
up
-7
hkmaly
2 years ago
Note: Before you get some idea like using md5 with password as way to prevent others tampering with message, read pages "Length extension attack" and "Hash-based message authentication code" on wikipedia. In short, naive constructions can be dangerously insecure. Use hash_hmac if available or reimplement HMAC properly without shortcuts.
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-15
terry _at_ scribendi_com
15 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.
up
-2
Steve M
6 months ago
I've found multiple sites suggesting the code:

md5(file_get_contents($filename));

Until recently, I hadn't noticed any issues with this locally... but then I tried to hash a 700MB file, with a 2048MB memory limit and kept getting out of memory errors...

There appears to be a limit to how long a string the md5() function can handle, and the alternative function is likely more memory efficient anyway. I would highly recommend to all who need file hashing (for detecting duplicates, not security digests) use the md5_file() function and NOT the regular string md5() function!

md5_file($filename);

Note, to those interested, as this was for a local application not a server, I was more concerned with results than memory efficiency. In a live environment, you would never want to read an entire file into memory at once when avoidable. (at the time of coding, I did not know of the alternative function)
up
-37
dionyziz at deviantart dot com
12 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;
}

?>
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