mhash_keygen_s2k(3) [php man page]

MHASH_KEYGEN_S2K(3)							 1						       MHASH_KEYGEN_S2K(3)

mhash_keygen_s2k - Generates a key

SYNOPSIS

       string mhash_keygen_s2k (int  $hash, string  $password, string  $salt, int  $bytes)

DESCRIPTION

	Generates a key according to the given $hash, using an user provided $password.

	This is the Salted S2K algorithm as specified in the OpenPGP document (RFC 2440).

	Keep  in  mind	that  user supplied passwords are not really suitable to be used as keys in cryptographic algorithms, since users normally
       choose keys they can write on keyboard. These passwords use only 6 to 7 bits per character (or less). It is highly recommended to use  some
       kind of transformation (like this function) to the user supplied key.

PARAMETERS

	      o $hash
		- The hash ID used to create the key. One of the MHASH_hashname constants.

	      o $password
		- An user supplied password.

	      o $salt
		-  Must  be  different and random enough for every key you generate in order to create different keys. Because $salt must be known
		when you check the keys, it is a good idea to append the key to it. Salt has a fixed length of 8 bytes and  will  be  padded  with
		zeros if you supply less bytes.

	      o $bytes
		- The key length, in bytes.

RETURN VALUES

	Returns the generated key as a string, or FALSE on error.

PHP Documentation Group 												       MHASH_KEYGEN_S2K(3)

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)