php man page for hash_pbkdf2

HASH_PBKDF2(3)								 1							    HASH_PBKDF2(3)

hash_pbkdf2 - Generate a PBKDF2 key derivation of a supplied password

SYNOPSIS
       string hash_pbkdf2 (string  $algo, string  $password, string  $salt, int  $iterations, [int  $length], [bool  $raw_output = false])

DESCRIPTION
PARAMETERS
	      o $algo
		- Name of selected hashing algorithm (i.e.  md5, sha256, haval160,4, etc..) See hash_algos(3) for a list of supported algorithms.

	      o $password
		- The password to use for the derivation.

	      o $salt
		- The salt to use for the derivation. This value should be generated randomly.

	      o $iterations
		- The number of internal iterations to perform for the derivation.

	      o $length
		-  The	length of the output string. If $raw_output is TRUE this corresponds to the byte-length of the derived key, if $raw_output
		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.

	      o $raw_output
		- When set to TRUE, outputs raw binary data.  FALSE outputs lowercase hexits.

RETURN VALUES
	Returns a string containing the derived key as lowercase hexits unless $raw_output is set to TRUE in which case the raw binary representa-
       tion of the derived key is returned.

ERRORS
/EXCEPTIONS
	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).

EXAMPLES
       Example #1

	      hash_pbkdf2(3) example, basic usage

	      <?php
	      $password = "password";
	      $iterations = 1000;

	      // Generate a random IV using mcrypt_create_iv(),
	      // openssl_random_pseudo_bytes() or another suitable source of randomness
	      $salt = mcrypt_create_iv(16, MCRYPT_DEV_URANDOM);

	      $hash = hash_pbkdf2("sha256", $password, $salt, $iterations, 20);
	      echo $hash;
	      ?>

	      The above example will output something similar to:

	      120fb6cffcf8b32c43e7

NOTES
       Caution

	       The PBKDF2 method can be used for hashing passwords for storage. However, it should be noted that password_hash(3) or crypt(3) with
	      CRYPT_BLOWFISH are better suited for password storage.

SEE ALSO
       crypt(3), password_hash(3), hash(3), hash_algos(3), hash_init(3), hash_hmac(3), hash_hmac_file(3).

PHP Documentation Group 													    HASH_PBKDF2(3)