php 한글 메뉴얼 도움말 검색 사이트 Generates cryptographically secure pseudo-random bytes [function.random-bytes]

설명

string random_bytes ( int $length )

Generates an arbitrary length string of cryptographic random bytes that are suitable for cryptographic use, such as when generating salts, keys or initialization vectors.

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

On Windows, » CryptGenRandom() will always be used.
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 an Exception will be thrown.

인수

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

반환값

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

오류/예외

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, an Error will be thrown.

예제

Example #1 random_bytes() example


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

위 예제의 출력 예시:

string(10) "385e33f741"

참고

random_int() - Generates cryptographically secure pseudo-random integers
openssl_random_pseudo_bytes() - Generate a pseudo-random string of bytes
bin2hex() - 바이너리 데이터를 16진 표현으로 변환