Regarding Ray Paseur's comment, the strings hash to:
0e462097431906509019562988736854
0e830400451993494058024219903391
The odds of getting a hash exactly matching the format /^0+e[0-9]+$/ are not high but are also not negligible.
It should be added as a general warning for all hash functions to always use the triple equals === for comparison.
Actually, the warning should be in the operators section when comparing string values! There are lots of warnings about string comparisons, but nothing specific about the format /^0+e[0-9]+$/.
md5
(PHP 4, PHP 5, PHP 7, PHP 8)
md5 — Calcule 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
Calcule le MD5 de la chaîne de caractères string en
utilisant l'algorithme » RSA Data
Security, Inc. MD5 Message-Digest Algorithm,
et retourne le résultat.
Liste de paramètres
-
string -
La chaîne.
-
binary -
Si le paramètre optionnel
binaryest défini àtrue, 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
add a note
User Contributed Notes 7 notes
yiminrong at yahoo dot ca ¶
3 years ago
Ray.Paseur sometimes uses Gmail ¶
5 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.
John ¶
15 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.
Steve M ¶
4 years 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)
Shane Allen ¶
21 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: " . $myrow['password'];
>
>outputs:
>
>php original hash from text: 0aed5d740d7fab4201e885019a36eace
>hash from perl: c18c9c57cb3658a50de06491a70b75cd
radon8472 at radon-software dot net ¶
8 years ago
<?php
function raw2hex($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
?>
hkmaly ¶
6 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.
