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openssl_random_pseudo_bytes
(PHP 5 >= 5.3.0, PHP 7)
openssl_random_pseudo_bytes — Generate a pseudo-random string of bytes
Description
$length
[, bool &$crypto_strong
] ) : 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 crypto_strong
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. 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.
TRUEif it did, otherwiseFALSE
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: 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)
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
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Steph