(PHP 5 >= 5.5.0, PHP 7)
hash_pbkdf2 — Generate a PBKDF2 key derivation of a supplied password
hash_pbkdf2 ( string $algo , string $password , string $salt , int $iterations [, int $length = 0 [, bool $binary = false ]] ) : string
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.
An E_WARNING will be raised 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 |
|---|---|
| 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 random IV using openssl_random_pseudo_bytes()
// random_bytes() or another suitable source of randomness
$salt = openssl_random_pseudo_bytes(16);
$hash = hash_pbkdf2("sha256", $password, $salt, $iterations, 20);
echo $hash;
?> The above example will output something similar to:
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.
© 1997–2020 The PHP Documentation Group
Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.hash-pbkdf2.php