openssl_random_pseudo_bytes(3) [php man page]

OPENSSL_RANDOM_PSEUDO_BYTES(3)						 1					    OPENSSL_RANDOM_PSEUDO_BYTES(3)

openssl_random_pseudo_bytes - Generate a pseudo-random string of bytes

SYNOPSIS

       string openssl_random_pseudo_bytes (int	$length, [bool	&$crypto_strong])

DESCRIPTION

	Generates a string of pseudo-random bytes, with the number of bytes determined by the $length parameter.

	It  also  indicates  if  a  cryptographically strong algorithm was used to produce the pseudo-random bytes, and does this via the optional
       $crypto_strong parameter. It's rare for this to be FALSE, but some systems may be broken or old.

PARAMETERS

	      o $length
		- The length of the desired string of bytes. Must be a positive integer. PHP will try to cast this parameter to a non-null integer
		to use it.

	      o $crypto_strong
		-  If  passed  into  the  function,  this  will  hold a boolean value that determines if the algorithm used was "cryptographically
		strong", e.g., safe for usage with GPG, passwords, etc.  TRUE if it did, otherwise FALSE

RETURN VALUES

	Returns the generated string of bytes on success, or FALSE on failure.

EXAMPLES

       Example #1

	      openssl_random_pseudo_bytes(3) example

	      <?php
	      for ($i = -1; $i <= 4; $i++) {
		  $bytes = openssl_random_pseudo_bytes($i, $cstrong);
		  $hex	 = bin2hex($bytes);

		  echo "Lengths: Bytes: $i and Hex: " . strlen($hex) . PHP_EOL;
		  var_dump($hex);
		  var_dump($cstrong);
		  echo PHP_EOL;
	      }
	      ?>

	      The above example will output something similar to:

	      Lengths: Bytes: -1 and Hex: 0
	      string(0) ""
	      NULL

	      Lengths: Bytes: 0 and Hex: 0
	      string(0) ""
	      NULL

	      Lengths: Bytes: 1 and Hex: 2
	      string(2) "42"
	      bool(true)

	      Lengths: Bytes: 2 and Hex: 4
	      string(4) "dc6e"
	      bool(true)

	      Lengths: Bytes: 3 and Hex: 6
	      string(6) "288591"
	      bool(true)

	      Lengths: Bytes: 4 and Hex: 8
	      string(8) "ab86d144"
	      bool(true)

SEE ALSO 
random_bytes(3), bin2hex(3), crypt(3), mt_rand(3), uniqid(3).
PHP Documentation Group 											    OPENSSL_RANDOM_PSEUDO_BYTES(3)

HASH(3) 								 1								   HASH(3)

hash - Generate a hash value (message digest)

SYNOPSIS

       string hash (string  $algo, string  $data, [bool  $raw_output = false])

DESCRIPTION

PARAMETERS

	      o $algo
		- Name of selected hashing algorithm (e.g. "md5", "sha256", "haval160,4", etc..)

	      o $data
		- Message to be hashed.

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

RETURN VALUES

	Returns  a  string  containing	the  calculated message digest as lowercase hexits unless $raw_output is set to true in which case the raw
       binary representation of the message digest is returned.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.4.0	|						    |
       |	|						    |
       |	| The tiger  algorithm	now  uses  big-endian  byte |
       |	| ordering. See also example below.		    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      A hash(3) example

	      <?php
	      echo hash('ripemd160', 'The quick brown fox jumped over the lazy dog.');
	      ?>

	      The above example will output:

	      ec457d0a974c48d5685a7efa03d137dc8bbde7e3

       Example #2

	      Calculate pre PHP-5.4 tiger hashes with PHP-5.4 and higher

	      <?php
	      function old_tiger($data = "", $width=192, $rounds = 3) {
		  return substr(
		      implode(
			  array_map(
			      function ($h) {
				  return str_pad(bin2hex(strrev($h)), 16, "0");
			      },
			      str_split(hash("tiger192,$rounds", $data, true), 8)
			  )
		      ),
		      0, 48-(192-$width)/4
		  );
	      }
	      echo hash('tiger192,3', 'a-string'), PHP_EOL;
	      echo old_tiger('a-string'), PHP_EOL;
	      ?>

	      Output of the above example in PHP 5.3:

	      146a7492719b3564094efe7abbd40a7416fd900179d02773
	      64359b7192746a14740ad4bb7afe4e097327d0790190fd16

	      Output of the above example in PHP 5.4:

	      64359b7192746a14740ad4bb7afe4e097327d0790190fd16
	      146a7492719b3564094efe7abbd40a7416fd900179d02773

SEE ALSO

       hash_file(3), hash_hmac(3), hash_init(3), md5(3), sha1(3).

PHP Documentation Group 														   HASH(3)