(PHP 5 >= 5.5.0, PHP 7, PHP 8)
hash_pbkdf2 — Generate a PBKDF2 key derivation of a supplied password
$algo
,$password
,$salt
,$iterations
,$length
= 0,$binary
= false
algo
Name of selected hashing algorithm (i.e. md5
,
sha256
, haval160,4
, etc..) See
hash_algos() for a list of supported algorithms.
password
The password to use for the derivation.
salt
The salt to use for the derivation. This value should be generated randomly.
iterations
The number of internal iterations to perform for the derivation.
length
The length of the output string. If binary
is true
this corresponds to the byte-length of the derived key, if
binary
is false
this corresponds to twice the
byte-length of the derived key (as every byte of the key is returned as
two hexits).
If 0
is passed, the entire output of the supplied
algorithm is used.
binary
When set to true
, outputs raw binary data. false
outputs lowercase
hexits.
Returns a string containing the derived key as lowercase hexits unless
binary
is set to true
in which case the raw
binary representation of the derived key is returned.
Throws a ValueError exception if the algorithm is
unknown, the iterations
parameter is less than or
equal to 0
, the length
is less
than 0
or the salt
is too long
(greater than INT_MAX
- 4
).
Version | Description |
---|---|
8.0.0 |
Now throws a ValueError exception on error.
Previously, false was returned and an E_WARNING
message was emitted.
|
7.2.0 | Usage of non-cryptographic hash functions (adler32, crc32, crc32b, fnv132, fnv1a32, fnv164, fnv1a64, joaat) was disabled. |
Example #1 hash_pbkdf2() example, basic usage
<?php
$password = "password";
$iterations = 1000;
// Generate a cryptographically secure random IV using random_bytes()
$salt = random_bytes(16);
$hash = hash_pbkdf2("sha256", $password, $salt, $iterations, 20);
var_dump($hash);
// for raw binary, the $length needs to be halved for equivalent results
$hash = hash_pbkdf2("sha256", $password, $salt, $iterations, 10, true);
var_dump(bin2hex($hash));?>
The above example will output something similar to:
string(20) "120fb6cffcf8b32c43e7" string(20) "120fb6cffcf8b32c43e7"
The PBKDF2 method can be used for hashing passwords for storage. However, it
should be noted that password_hash() or
crypt() with CRYPT_BLOWFISH
are
better suited for password storage.