(PHP 7, PHP 8)
random_bytes — Get cryptographically secure random bytes
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.
此函数使用的随机性来源先后顺序如下:
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 如果 CCRandomGenerateBytes 在编译时可用):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
注意: 虽然此函数是 PHP 7.0 添加到 PHP 中,但是从 PHP 5.2 到 PHP 5.6 都可以用 » 用户级实现。
length
The length of the random string that should be returned in bytes; must be 1
or greater.
A string containing the requested number of cryptographically secure random bytes.
length
is less than 1
,
a ValueError will be thrown.
版本 | 说明 |
---|---|
8.2.0 | In case of a CSPRNG failure, this function will now throw a Random\RandomException. Previously a plain Exception was thrown. |
示例 #1 random_bytes() example
<?php
$bytes = random_bytes(5);
var_dump(bin2hex($bytes));
?>
以上示例的输出类似于:
string(10) "385e33f741"