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PHP | random_bytes () Function
  • Last Updated : 09 Jul, 2018

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 reult and convert by binaryhexa
var_dump(bin2hex($length));
?>
Output:
string(8) "e62a94a2"




<?php
//random_bytes () function in PHP
$length = random_bytes('6');
  
//Print the reult and convert by binaryhexa
var_dump(bin2hex($length));
?>
Output:
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:
http://php.net/manual/en/function.random-bytes.php

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