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 $cipher_algo): int|false

获取密码初始化向量(iv)长度。

参数

cipher_algo: 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。

示例

示例 #1 openssl_cipher_iv_length() 范例

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

echo $ivlen;
?>

以上示例的输出类似于：

改进此页面

了解如何改进此页面 • 提交拉取请求 • 报告一个错误

＋添加备注

用户贡献的备注 2 notes

down

Tim Hunt ¶

9 years ago

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

down

-3

Vee W. ¶

6 years ago

<?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.