(PHP 5 >= 5.3.0, PHP 7)
openssl_random_pseudo_bytes — Generate a pseudo-random string of bytes
$length
[, bool &$crypto_strong
] )
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 crypto_strong
parameter. It's rare for this to be FALSE, but some systems may be broken or old.
lengthThe length of the desired string of bytes. Must be a positive integer. PHP will try to cast this parameter to a non-null integer to use it.
crypto_strong
If passed into the function, this will hold a boolean value that determines
if the algorithm used was "cryptographically strong", e.g., safe for usage with GPG,
passwords, etc. TRUE if it did, otherwise FALSE
Returns the generated string of bytes on success, 或者在失败时返回 FALSE.
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;
}
?>
以上例程的输出类似于：
Lengths: Bytes: -1 and Hex: 0 string(0) "" NULL Lengths: Bytes: 0 and Hex: 0 string(0) "" NULL 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)