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)

MT_RAND(3)								 1								MT_RAND(3)

mt_rand - Generate a better random value

SYNOPSIS

       int mt_rand (void  )

DESCRIPTION

       int mt_rand (int  $min, int  $max)

	Many  random  number  generators of older libcs have dubious or unknown characteristics and are slow. By default, PHP uses the libc random
       number generator with the rand(3) function. The mt_rand(3) function is a drop-in replacement for this. It uses a  random  number  generator
       with  known  characteristics  using  the   Mersenne Twister, which will produce random numbers four times faster than what the average libc
       rand() provides.

	If called without the optional $min, $max arguments mt_rand(3) returns a pseudo-random value between 0 and mt_getrandmax(3). If you want a
       random number between 5 and 15 (inclusive), for example, use mt_rand(5, 15).

       Caution

	      This  function  does  not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a
	      cryptographically secure value, consider using random_int(3), random_bytes(3), or openssl_random_pseudo_bytes(3) instead.

PARAMETERS

	      o $min
		- Optional lowest value to be returned (default: 0)

	      o $max
		- Optional highest value to be returned (default: mt_getrandmax(3))

RETURN VALUES

	A random integer value between $min (or 0) and $max (or mt_getrandmax(3), inclusive), or FALSE if $max is less than $min.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.4	|						    |
       |	|						    |
       |	|  Issues an E_WARNING and returns FALSE if $max  < |
       |	| $min. 					    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      mt_rand(3) example

	      <?php
	      echo mt_rand() . "
";
	      echo mt_rand() . "
";

	      echo mt_rand(5, 15);
	      ?>

	      The above example will output something similar to:

	      1604716014
	      1478613278
	      6

NOTES

       Caution

	       The  distribution of mt_rand(3) return values is biased towards even numbers on 64-bit builds of PHP when $max is beyond 2^32. This
	      is because if $max is greater than the value returned by mt_getrandmax(3), the output of the random number generator must be  scaled
	      up.

SEE ALSO

       mt_srand(3), mt_getrandmax(3), random_int(3), random_bytes(3), openssl_random_pseudo_bytes(3), rand(3).

PHP Documentation Group 														MT_RAND(3)