Question

I’m trying to do a function to hash passwords with this php function: http://be.php.net/manual/en/function.hash-pbkdf2.php.

Here is the code:

$hash_algo = "sha256";
$password = "password";
$salt = "salt";
$iterations = 1;
$length = 1;
$raw_output = false;

$hash = hash_pbkdf2($hash_algo, $password, $salt, $iterations ,$length ,$raw_output);

echo $hash;

I got this error: Fatal error: Call to undefined function hash_pbkdf2().

How can the function be undefined???

PS: All the values of my variables are set just for testing the function. Obviously the salt will not be “salt”, etc.

Answer 1

EDIT: As of PHP 5.5.0 this function is now bundled into the core library.

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This function is not (yet anyway) available in core PHP. It was proposed not that long ago and so far you can only get it as a patch.

You can use crypt or hash instead.
crypt is actually suggested in hash_pbkdf2 documentation:

Caution
The PBKDF2 method can be used for hashing passwords for storage (it is NIST approved for that use). However, it should be noted that CRYPT_BLOWFISH is better suited for password storage and should be used instead via crypt().