There is a compatibility pack available for PHP versions 5.3.7 and later, so you don't have to wait on version 5.5 for using this function. It comes in form of a single php file:
https://github.com/ircmaxell/password_compat
password_hash
(PHP 5 >= 5.5.0, PHP 7)
password_hash — Erstellt einen Passwort-Hash
Beschreibung
string password_hash
( string
$password
, integer $algo
[, array $options
] )password_hash() erstellt einen neuen Passwort-Hash und benutzt dabei einen starken Einweg-Hashing-Algorithmus.
Die folgenden Algorithmen werden zur Zeit unterstützt:
-
PASSWORD_DEFAULT- Benutzt den bcrypt-Algorithmus (Standard in PHP 5.5.0). Beachte, dass sich diese Konstante mit der Zeit ändern wird, wenn stärkere Algorithmen in PHP implementiert werden. Aus diesem Grund kann sich die Länge des zurückgegebenen Strings mit der Zeit ändern. Es wird deshalb empfohlen das Ergebnis in einem Datenbankfeld zu speichern, das mehr als 60 Zeichen speichern kann. (z.B. 255 Zeichen). -
PASSWORD_BCRYPT- Benutzt denCRYPT_BLOWFISH-Algorithmus zum Erstellen des Hashes. Dies erstellt einen crypt()-kompatiblen Hash und benutzt die "$2y$"-Kennung. Es wird immer ein 60 Zeichen langer String zurückgegeben, Im Fehlerfall wirdFALSEzurückgegeben..Unterstützte Optionen:
-
salt - to manually provide a salt to use when hashing the password. Note that this will override and prevent a salt from being automatically generated.
If omitted, a random salt will be generated by password_hash() for each password hashed. This is the intended mode of operation.
-
cost - which denotes the algorithmic cost that should be used. Examples of these values can be found on the crypt() page.
If omitted, a default value of 10 will be used. This is a good baseline cost, but you may want to consider increasing it depending on your hardware.
-
Parameter-Liste
-
password -
Das Passwort des Benutzers.
-
algo -
Eine Konstante für den Passwort-Algorithmus, die den Algorithmus zum hashen des Passwortes angibt.
-
options -
Ein assoziatives Array mit Optionen. Siehe auch Konstanten für Passwort-Algorithmen für Informationen zu den von dein jeweiligen Algorithmen unterstützten Optionen.
If omitted, a random salt will be created and the default cost will be used.
Rückgabewerte
Returns the hashed password, Im Fehlerfall wird FALSE zurückgegeben..
Beispiele
Beispiel #1 password_hash() example
<?php
/**
* We just want to hash our password using the current DEFAULT algorithm.
* This is presently BCRYPT, and will produce a 60 character result.
*
* Beware that DEFAULT may change over time, so you would want to prepare
* By allowing your storage to expand past 60 characters (255 would be good)
*/
echo password_hash("rasmuslerdorf", PASSWORD_DEFAULT)."\n";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
$2y$10$.vGA1O9wmRjrwAVXD98HNOgsNpDczlqm3Jq7KnEd1rVAGv3Fykk1a
Beispiel #2 password_hash() example setting cost manually
<?php
/**
* In this case, we want to increase the default cost for BCRYPT to 12.
* Note that we also switched to BCRYPT, which will always be 60 characters.
*/
$options = [
'cost' => 12,
];
echo password_hash("rasmuslerdorf", PASSWORD_BCRYPT, $options)."\n";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
$2y$12$QjSH496pcT5CEbzjD/vtVeH03tfHKFy36d4J0Ltp3lRtee9HDxY3K
Beispiel #3 password_hash() example setting salt manually
<?php
/**
* Note that the salt here is randomly generated.
* Never use a static salt or one that is not randomly generated.
*
* For the VAST majority of use-cases, let password_hash generate the salt randomly for you
*/
$options = [
'cost' => 11,
'salt' => mcrypt_create_iv(22, MCRYPT_DEV_URANDOM),
];
echo password_hash("rasmuslerdorf", PASSWORD_BCRYPT, $options)."\n";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
$2y$11$q5MkhSBtlsJcNEVsYh64a.aCluzHnGog7TQAKVmQwO9C8xb.t89F.
Beispiel #4 password_hash() example finding a good cost
<?php
/**
* This code will benchmark your server to determine how high of a cost you can
* afford. You want to set the highest cost that you can without slowing down
* you server too much. 10 is a good baseline, and more is good if your servers
* are fast enough.
*/
$timeTarget = 0.2;
$cost = 9;
do {
$cost++;
$start = microtime(true);
password_hash("test", PASSWORD_BCRYPT, ["cost" => $cost]);
$end = microtime(true);
} while (($end - $start) < $timeTarget);
echo "Appropriate Cost Found: " . $cost . "\n";
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
Appropriate Cost Found: 11
Anmerkungen
Achtung
It is strongly recommended that you do not generate your own salt for this function. It will create a secure salt automatically for you if you do not specify one.
Hinweis:
It is recommended that you should test this function on your servers, and adjust the cost parameter so that execution of the function takes approximately 0.1 to 0.5 seconds. The script in the above example will help you choose a good cost value for your hardware.
Hinweis: Updates to supported algorithms by this function (or changes to the default one) must follow the follwoing rules:
- Any new algorithm must be in core for at least 1 full release of PHP prior to becoming default. So if, for example, a new algorithm is added in 5.5.5, it would not be eligible for default until 5.7 (since 5.6 would be the first full release). But if a different algorithm was added in 5.6.0, it would also be eligible for default at 5.7.0.
- The default should only change on a full release (5.6.0, 6.0.0, etc) and not on a revision release. The only exception to this is in an emergency when a critical security flaw is found in the current default.
Siehe auch
- password_verify() - Überprüft, ob ein Passwort und ein Hash zusammenpassen
- crypt() - Einweg-String-Hashing
- » userland implementation
add a note
User Contributed Notes 11 notes
martinstoeckli ¶
4 years ago
jay at jayblanchard dot net ¶
2 months ago
Be care when using the example from the documentation which concatenates a newline character <code>\n</code> to the end of the hash, i.e.:
<code>echo password_hash("rasmuslerdorf", PASSWORD_DEFAULT)."\n";</code>
People are storing the hash with the concatenated newline and consequently <code>password_verify()</code> will fail.
nicoSWD ¶
3 years ago
I agree with martinstoeckli,
don't create your own salts unless you really know what you're doing.
By default, it'll use /dev/urandom to create the salt, which is based on noise from device drivers.
And on Windows, it uses CryptGenRandom().
Both have been around for many years, and are considered secure for cryptography (the former probably more than the latter, though).
Don't try to outsmart these defaults by creating something less secure. Anything that is based on rand(), mt_rand(), uniqid(), or variations of these is *not* good.
Cloxy ¶
3 years ago
You can produce the same hash in php 5.3.7+ with crypt() function:
<?php
$salt = mcrypt_create_iv(22, MCRYPT_DEV_URANDOM);
$salt = base64_encode($salt);
$salt = str_replace('+', '.', $salt);
$hash = crypt('rasmuslerdorf', '$2y$10$'.$salt.'$');
echo $hash;
?>
Lyo Mi ¶
1 year ago
Please note that password_hash will ***truncate*** the password at the first NULL-byte.
http://blog.ircmaxell.com/2015/03/security-issue-combining-bcrypt-with.html
If you use anything as an input that can generate NULL bytes (sha1 with raw as true, or if NULL bytes can naturally end up in people's passwords), you may make your application much less secure than what you might be expecting.
The password
$a = "\01234567";
is zero bytes long (an empty password) for bcrypt.
The workaround, of course, is to make sure you don't ever pass NULL-bytes to password_hash.
anonymous ¶
1 year ago
Pay close attention to the maximum allowed length of the password parameter! If you exceed the maximum length, it will be truncated without warning.
If you prepend your own salt/pepper to the password, and that salt/pepper exceeds the maximum length, then this function will truncate the actual password. That means password_verify() will return true with ANY password using the same salt/pepper.
It might be a good idea to append any salt/pepper to the end of the password instead.
VladimirMozhenkov at yahoo dot com ¶
1 year ago
Note that this function can return NULL. It does so if you provide an incorrect constant as an algorythm. I had the following:
$password = password_hash($password1, PASSWORD_BDCRYPT, array( 'cost' => 10 ));
and i couldn't understand why i kept having NULL written in $password; it was a simple fact that the constant was PASSWORD_BCRYPT.
Mike Robinson ¶
2 years ago
For passwords, you generally want the hash calculation time to be between 250 and 500 ms (maybe more for administrator accounts). Since calculation time is dependent on the capabilities of the server, using the same cost parameter on two different servers may result in vastly different execution times. Here's a quick little function that will help you determine what cost parameter you should be using for your server to make sure you are within this range (note, I am providing a salt to eliminate any latency caused by creating a pseudorandom salt, but this should not be done when hashing passwords):
<?php
/**
* @Param int $min_ms Minimum amount of time in milliseconds that it should take
* to calculate the hashes
*/
function getOptimalBcryptCostParameter($min_ms = 250) {
for ($i = 4; $i < 31; $i++) {
$options = [ 'cost' => $i, 'salt' => 'usesomesillystringforsalt' ];
$time_start = microtime(true);
password_hash("rasmuslerdorf", PASSWORD_BCRYPT, $options);
$time_end = microtime(true);
if (($time_end - $time_start) * 1000 > $min_ms) {
return $i;
}
}
}
echo getOptimalBcryptCostParameter(); // prints 12 in my case
?>
martinstoeckli ¶
4 years ago
In most cases it is best to omit the salt parameter. Without this parameter, the function will generate a cryptographically safe salt, from the random source of the operating system.
cottton ¶
3 years ago
if you thought
"why is the salt included in the hash and is it save when i store it as it is in my db?"
Answer i found:
The salt just has to be unique. It not meant to be a secret.
As mentioned in notes and docu before: let password_hash() take care of the salt.
With the unique salt you force the attacker to crack the hash.
The hash is unique and cannot be found at rainbow tables.
darkflib ¶
1 year ago
Timings:
Note: 1 and 2 for cost are invalid.
3 - 0.085115432739258ms
4 - 1.6319751739502ms
5 - 2.9170513153076ms
6 - 5.511999130249ms
7 - 10.689973831177ms
8 - 20.890951156616ms
9 - 41.686058044434ms
10 - 84.12504196167ms (default)
11 - 168.97416114807ms
12 - 334.79714393616ms
13 - 680.88603019714ms
14 - 1342.1139717102ms
15 - 2706.4559459686ms
16 - 5404.2019844055ms
17 - 10615.604162216ms
For an average site the default of 10 is probably a sane enough value.
