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md5

(PHP 4, PHP 5, PHP 7)

md5Calcule le md5 d'une chaîne

Avertissement

Il n'est pas recommandé d'utiliser cette fonction pour sécuriser les mots de passe, en raison de la nature rapide de cet algorithme de hachage. Voir F.A.Q du hachage des mots de passe pour plus de détails et les bonnes pratiques.

Description

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

Calcule le MD5 de la chaîne de caractères str en utilisant l'algorithme » RSA Data Security, Inc. MD5 Message-Digest Algorithm, et retourne le résultat.

Liste de paramètres

str

La chaîne.

raw_output

Si le paramètre optionnel raw_output est défini à TRUE, alors le md5 est retourné au format binaire brut avec une longueur de 16.

Valeurs de retour

Retourne le md5 de la chaîne, sous la forme d'un nombre hexadécimal de 32 caractères.

Exemples

Exemple #1 Exemple avec md5()

<?php
$str 
'apple';

if (
md5($str) === '1f3870be274f6c49b3e31a0c6728957f') {
    echo 
"Voulez-vous une golden ou une spartan?";
}
?>

Voir aussi

  • md5_file() - Calcule le md5 d'un fichier
  • sha1_file() - Calcule le sha1 d'un fichier
  • crc32() - Calcule la somme de contrôle CRC32
  • sha1() - Calcule le sha1 d'une chaîne de caractères
  • hash() - Génère une valeur de hachage (empreinte numérique)
  • crypt() - Hachage à sens unique (indéchiffrable)
  • password_hash() - Crée une clé de hachage pour un mot de passe

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User Contributed Notes 8 notes

up
14
John
11 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
7
Ray.Paseur sometimes uses Gmail
2 years 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.
up
1
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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-8
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
-8
hkmaly
3 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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-19
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
-4
Steve M
10 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
-42
dionyziz at deviantart dot com
13 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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