php - Viewing the returned string of openssl_random_psuedo_bytes() -

why doesn't echo openssl_random_pseudo_bytes(12) print out if concatinate string show output? according the manual return type of openssl_random_pseudo_bytes string why there problem? tried type casting (string) , didn't work.

the openssl_random_pseudo_bytes(...) function returns binary number in form of string (i.e. ascii value(s)) of specified length.

for example, 1 possible output of:

$number_of_bytes = 1; $bin = openssl_random_pseudo_bytes($number_of_bytes, $cstrong); $hex=bin2hex($bin); $dec=hexdec($hex); 

could be:

var_dump($bin); // string(1) "ã" var_dump($hex); // string(2) "e3" var_dump($dec); // int(227) var_dump($cstrong); // bool(true) 

notes:

1. $dec integer random value can equal (at most) 2 ^ (8 * $number_of_bytes) - 1.
   • where 1 byte comprises 8 bits
   • php has integer overflow limitation of @ 2^31-1 or 2^63-1 bits (the limits of signed integers use 4 bytes or 8 bytes depending on whether have 32 or 64 bit platform respectively) , after overflows / casts float value (potentially limiting precision).
     • so calling 4 (or 8) bytes, half of time $dec float
2. at higher numbers of bytes, $bin , $hex values maintain precision , accuracy (because of digits/bits kept in (variable length) string).
3. openssl_random_pseudo_bytes returns false when fails.
4. $cstrong!==true indicates openssl_random_pseudo_bytes did not return result generated cryptographically strong algorithm. (http://php.net/openssl_random_pseudo_bytes)

---

example function (demonstrates handling false return value or when $cstrong false)

class random {     public static function get($number_of_bytes=4)     {         $binary_value = openssl_random_pseudo_bytes($number_of_bytes, $cstrong);          // unable produce cryptographically strong value         if($binary_value==false || $cstrong!==true) return false; // failure          // other processing         $hexadecimal_value = bin2hex($binary_value);         $decimal_value = hexdec($hexadecimal_value);            // returns positive integer (or float          // in case of integer overflow)         return $decimal_value;      } } 

manual: http://php.net/openssl_random_pseudo_bytes

usage

echo random::get(12); // returns large float value of time