openssl_random_pseudo_bytes
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
openssl_random_pseudo_bytes — Generate a pseudo-random string of bytes
Description
$length, bool &$strong_result = null): string
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 strong_result
parameter. It's rare for this to be false, but some systems may be broken or old.
Parameters
-
length -
The length of the desired string of bytes. Must be a positive integer less than or equal to
2147483647. PHP will try to cast this parameter to a non-null integer to use it. -
strong_result -
If passed into the function, this will hold a bool value that determines if the algorithm used was "cryptographically strong", e.g., safe for usage with GPG, passwords, etc.
trueif it did, otherwisefalse
Return Values
Returns the generated string of bytes.
Errors/Exceptions
openssl_random_pseudo_bytes() throws an Exception on failure.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
strong_result is nullable now.
|
| 7.4.0 |
The function no longer returns false on failure, but throws an Exception instead.
|
Examples
Example #1 openssl_random_pseudo_bytes() 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: 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() - Generates cryptographically secure pseudo-random bytes
- bin2hex() - Convert binary data into hexadecimal representation
- crypt() - One-way string hashing
- mt_rand() - Generate a random value via the Mersenne Twister Random Number Generator
- uniqid() - Generate a unique ID
