Generates cryptographically secure pseudo-random bytes (original) (raw)

random_bytes

(PHP 7)

random_bytes — Generates cryptographically secure pseudo-random bytes

Description

random_bytes ( int $length ) : string

The sources of randomness used for this function are as follows:

• On Windows,» CryptGenRandom() will always be used. As of PHP 7.2.0, the» CNG-API will always be used instead.
• On Linux, the» getrandom(2) syscall will be used if available.
• On other platforms, /dev/urandom will be used.
• If none of the aforementioned sources are available, then anException will be thrown.

Note: Although this function was added to PHP in PHP 7.0, a» userland implementation is available for PHP 5.2 to 5.6, inclusive.

Parameters

length

The length of the random string that should be returned in bytes.

Return Values

Returns a string containing the requested number of cryptographically secure random bytes.

Errors/Exceptions

• If an appropriate source of randomness cannot be found, an Exception will be thrown.
• If invalid parameters are given, a TypeError will be thrown.
• If an invalid length of bytes is given, anError will be thrown.

Examples

Example #1 random_bytes() example

<?php $bytes = random_bytes(5); var_dump(bin2hex($bytes)); ?>

The above example will output something similar to:

See Also

• random_int() - Generates cryptographically secure pseudo-random integers
• openssl_random_pseudo_bytes() - Generate a pseudo-random string of bytes
• bin2hex() - Convert binary data into hexadecimal representation