openssl_cipher_iv_length

(PHP 5 >= 5.3.3, PHP 7, PHP 8)

openssl_cipher_iv_length — 获取密码iv长度

说明

openssl_cipher_iv_length ( string $method ) : int

获取密码初始化向量(iv)长度。

参数

method: 密码的方法，更多值查看 openssl_get_cipher_methods() 函数。

返回值

成功，返回密码长度, 失败返回 false .

错误／异常

当密码方法未知时，抛出一个E_WARNING 级的错误。

范例

Example #1 openssl_cipher_iv_length() 范例


<?php
$method = 'AES-128-CBC';
$ivlen = openssl_cipher_iv_length($method);

echo $ivlen;
?>

以上例程的输出类似于：

User Contributed Notes

Vee W. 07-Apr-2018 04:30


<?php

$ciphers = openssl_get_cipher_methods();



//ECB mode should be avoided

$ciphers = array_filter($ciphers, function ($n) {

    return stripos($n, "ecb") === FALSE;

});

    

// At least as early as Aug 2016, Openssl declared the following weak: RC2, RC4, DES, 3DES, MD5 based

$ciphers = array_filter($ciphers, function ($c) {

    return stripos($c, "des") === FALSE;

});

$ciphers = array_filter($ciphers, function ($c) {

    return stripos($c, "rc2") === FALSE;

});

$ciphers = array_filter($ciphers, function ($c) {

    return stripos($c, "rc4") === FALSE;

});

$ciphers = array_filter($ciphers, function ($c) {

    return stripos($c, "md5") === FALSE;

});



if (is_array($ciphers)) {

    foreach ($ciphers as $cipher) {

        echo $cipher.': ';

        echo openssl_cipher_iv_length($cipher);

        echo "<br>\n";

    }

}

?>



Will be...

AES-xxx-xxx is 16

BF-xxx is 8

CAMELLIA-xxx is 16

CAST5-xxx is 8

IDEA-xxx is 8

SEED-xxx is 16



lower case:

aes-xxx-xxx are mixed between 16 and 12.

id-aes-xxx are mixed between 12 and 8.

The values above are tested with PHP 5.5 - 5.6 on Windows. In PHP 7.x is different than this.

Tim Hunt 10-Dec-2014 05:37


The return value is a length in bytes. (Not bits, or anything else.)