PHP | random_bytes () Function

The random_bytes()is an inbuilt function in PHP. The main function is to generate cryptographically secure pseudo-random bytes. It generates cryptographic random bytes of arbitrary string length. The different sources of randomness used in this function, they are as follows:-

• Window : CryptGenRandom() function.
• Linux : getrandom(2) system call function.

Syntax :

String random_bytes ( int $length )

Parameter : It is the length of random string, returned in bytes. Return Value: The function returns the cryptographically secure random bytes in string. Examples:

Input : length = 7
Output :string(14) "cbd392c01352b0"

Below programs illustrate the random_bytes () function in PHP. Program 1: 

<?php
//random_bytes () function in PHP
$length = random_bytes('4');

//Print the result and convert by binaryhexa
var_dump(bin2hex($length));
?>

string(8) "e62a94a2"

<?php
//random_bytes () function in PHP
$length = random_bytes('6');

//Print the result and convert by binaryhexa
var_dump(bin2hex($length));
?>

string(12) "808fc44d325b"

Exception Error :

• Invalid parameter will give TypeError .
• Invalid length of bytes gives Error.
• If source of randomness is not found then Exception will be thrown.

References: https://www.php.net/manual/en/function.random-bytes.php