hash_init(3) [php man page]

HASH_INIT(3)								 1							      HASH_INIT(3)

hash_init - Initialize an incremental hashing context

SYNOPSIS

       resource hash_init NULL (string	$algo, [int  $options], [string  $key])

DESCRIPTION

PARAMETERS

	      o $algo
		-  Name  of  selected  hashing	algorithm  (i.e.  "md5",  "sha256",  "haval160,4",  etc..). For a list of supported algorithms see
		hash_algos(3).

	      o $options
		- Optional settings for hash generation, currently supports only one option: HASH_HMAC. When specified, the $key  must	be  speci-
		fied.

	      o $key
		-  When  HASH_HMAC is specified for $options, a shared secret key to be used with the HMAC hashing method must be supplied in this
		parameter.

RETURN VALUES

	Returns a Hashing Context resource for use with hash_update(3), hash_update_stream(3), hash_update_file(3), and hash_final(3).

EXAMPLES

       Example #1

	      Incremental hashing example

	      <?php
	      $ctx = hash_init('md5');
	      hash_update($ctx, 'The quick brown fox ');
	      hash_update($ctx, 'jumped over the lazy dog.');
	      echo hash_final($ctx);
	      ?>

	      The above example will output:

	      5c6ffbdd40d9556b73a21e63c3e0e904

SEE ALSO

       hash(3), hash_algos(3), hash_file(3), hash_hmac(3), hash_hmac_file(3).

PHP Documentation Group 													      HASH_INIT(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)