<?php
function str_rand(int $length = 64){ // 64 = 32
$length = ($length < 4) ? 4 : $length;
return bin2hex(random_bytes(($length-($length%2))/2));
}
var_dump(str_rand());
// d6199909d0b5fdc22c9db625e4edf0d6da2b113b21878cde19e96f4afe69e714
?>
random_bytes
(PHP 7, PHP 8)
random_bytes — Get cryptographically secure random bytes
Descrizione
Generates a string containing uniformly selected random bytes with the requested length.
As the returned bytes are selected completely randomly, the resulting string is likely to contain unprintable characters or invalid UTF-8 sequences. It may be necessary to encode it before transmission or display.
The randomness generated by this function is suitable for all applications, including the generation of long-term secrets, such as encryption keys.
The sources of randomness in the order of priority are as follows:
-
Linux: » getrandom(), /dev/urandom
-
FreeBSD >= 12 (PHP >= 7.3): » getrandom(), /dev/urandom
-
Windows (PHP >= 7.2): » CNG-API
Windows: » CryptGenRandom
-
macOS (PHP >= 8.2; >= 8.1.9; >= 8.0.22 if CCRandomGenerateBytes is available at compile time): CCRandomGenerateBytes()
macOS (PHP >= 8.1; >= 8.0.2): arc4random_buf(), /dev/urandom
-
NetBSD >= 7 (PHP >= 7.1; >= 7.0.1): arc4random_buf(), /dev/urandom
-
OpenBSD >= 5.5 (PHP >= 7.1; >= 7.0.1): arc4random_buf(), /dev/urandom
-
DragonflyBSD (PHP >= 8.1): » getrandom(), /dev/urandom
-
Solaris (PHP >= 8.1): » getrandom(), /dev/urandom
- Any combination of operating system and PHP version not previously mentioned: /dev/urandom
- If none of the sources are available or they all fail to generate randomness, then a Random\RandomException will be thrown.
Nota: Although this function was added to PHP in PHP 7.0, a » userland implementation is available for PHP 5.2 to 5.6, inclusive.
Elenco dei parametri
-
length -
The length of the random string that should be returned in bytes; must be
1or greater.
Valori restituiti
A string containing the requested number of cryptographically secure random bytes.
Errori/Eccezioni
- If an appropriate source of randomness cannot be found, a Random\RandomException will be thrown.
-
If the value of
lengthis less than1, a ValueError will be thrown.
Log delle modifiche
| Versione | Descrizione |
|---|---|
| 8.2.0 | In case of a CSPRNG failure, this function will now throw a Random\RandomException. Previously a plain Exception was thrown. |
Esempi
Example #1 random_bytes() example
<?php
$bytes = random_bytes(5);
var_dump(bin2hex($bytes));
?>Il precedente esempio visualizzerà qualcosa simile a:
string(10) "385e33f741"
Vedere anche:
- Random\Randomizer::getBytes() - Get random bytes
- random_int() - Get a cryptographically secure, uniformly selected integer
- bin2hex() - Converte i dati binari nella rappresentazione esadecimale
- base64_encode() - Encodes data with MIME base64
add a note
User Contributed Notes 1 note
ccbsschucko at gmail dot com ¶
6 years ago
