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Core_Text::rc4

优化版rc4加密解密

string Core_Text::rc4( string $string [, string $is_decode = bool true , string $key = null , number $expiry = integer 0 ] )

参数列表

参数类型描述默认值

$string string $string

$is_decode string $is_decode bool true

$key string $key null

$expiry number $expiry integer 0

参数	类型	描述	默认值
`$string`	`string`	$string
`$is_decode`	`string`	$is_decode	bool true
`$key`	`string`	$key	null
`$expiry`	`number`	$expiry	integer 0

返回值

string

File: ./core/classes/text.class.php

protected static function rc4($string, $is_decode = true, $key = null, $expiry = 0)
{
    $ckey_length = 4;
    $key  = md5($key?$key:serialize(Core::config('database')).serialize(Core::config('cache')));
    $keya = md5(substr($key, 0, 16));
    $keyb = md5(substr($key, 16, 16));
    $keyc = $ckey_length ? ($is_decode == true ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : '';

    $cryptkey = $keya.md5($keya.$keyc);
    $key_length = strlen($cryptkey);

    $string = $is_decode == true ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string.$keyb), 0, 16) . $string;
    $string_length = strlen($string);

    $result = '';
    $box = range(0, 255);

    $rndkey = array();
    for($i = 0; $i <= 255; $i++)
    {
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);
    }

    for($j = $i = 0; $i < 256; $i++)
    {
        $j       = ($j + $box[$i] + $rndkey[$i]) % 256;
        $tmp     = $box[$i];
        $box[$i] = $box[$j];
        $box[$j] = $tmp;
    }

    for($a = $j = $i = 0; $i < $string_length; $i++)
    {
        $a = ($a + 1) % 256;
        $j = ($j + $box[$a]) % 256;
        $tmp = $box[$a];
        $box[$a] = $box[$j];
        $box[$j] = $tmp;
        $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
    }

    if($is_decode == true)
    {
        if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16))
        {
            return substr($result, 26);
        }
        else
        {
            return '';
        }
    }
    else
    {
        return $keyc . str_replace('=', '', base64_encode($result));
    }
}