将任意内容转换为零宽字符，“隐藏”内容

width0.php

<?php

/**
 * http://ucren.com/blog/archives/549
 * 利用零宽字符“隐藏”信息
 * 每个字符都有一个唯一的编码，将编码以 2 进制表示得到 01.. 的字串，把 1 替换成 U+200C，把 0 替换成 U+200D 就得到一个全零宽空白的字符串
 * 在 unicode 里，至少有 U+200B, U+200C, U+200D 和 U+FEFF 四个零宽字符
 */


function content2width0($content = ''){
    $hex = bin2hex($content);

    $bin = '';
    $hex_len = strlen($hex);
    $step = 8;
    for($i = 0; $i < $hex_len; $i += $step){
        $substr = substr($hex, $i, $step);
        $substr_len = strlen($substr);
        $padding = min($step, $substr_len) * 4;
        $bin .= str_pad(base_convert($substr, 16, 2), $padding, '0', STR_PAD_LEFT);
    }
    unset($i, $hex_len, $step, $padding, $substr, $substr_len);

    $width0 = str_replace(array('0', '1'), array(hex2bin('e2808c'), hex2bin('e2808d')), $bin);

    return $width0;
}

function width02content($width0 = ''){
    $bin = str_replace(array(hex2bin('e2808c'), hex2bin('e2808d')), array('0', '1'), $width0);

    $hex = '';
    $bin_len = strlen($bin);
    $step = 32;
    for($i = 0; $i < $bin_len; $i += $step){
        $substr = substr($bin, $i, $step);
        $substr_len = strlen($substr);
        $padding = floor(min($step, $substr_len) / 4);
        $hex .= str_pad(base_convert($substr, 2, 16), $padding, '0', STR_PAD_LEFT);
    }
    unset($i, $bin_len, $step, $padding, $substr, $substr_len);

    $content = hex2bin($hex);
    return $content;
}


$content = '字符:§№☆★○●◎◇◆□■△▲※→←↑↓〓＃＆＠＼︿＿￣'.PHP_EOL;
$content .= '!@#$%^&*()'.PHP_EOL;
$content .= '1234567890'.PHP_EOL;
$content .= 'qwertyuiopasdfghjklzxcvbnm'.PHP_EOL;
$content .= '中abc英!@#字☆★○●◎符数123字混排。。”“'.PHP_EOL;
$content .= '！＠＃＄％＾＆＊（）＿＋－＝～｀＼／．，＇；］［｛｝｜、'.PHP_EOL;
$content .= '韩语：컴퓨터';
$content .= '蒙古语:🤣 🤠 🤡 🤥 🤤 🤢 🤧 🤴 🤶 🤵 🤷 🤦 🤰 🕺 🤳 🤞 🤙 🤛 🤜 🤚 🤝 🖤 🦍 ';
$content .= '日语:コンピュータ技術の魔法';
$content .= '✰';
$content .= 'emoji:😃😂😊😉😁😄';  //emoji
$content .= 'emoji2:🤣 🤠 🤡 🤥 🤤 🤢 🤧 🤴 🤶 🤵 🤷 🤦 🤰 🕺 🤳 🤞 🤙 🤛 🤜 🤚 🤝 🖤 🦍 ';
$content .= '===============';

file_put_contents('width0.txt', content2width0($content));

var_dump(width02content(file_get_contents('width0.txt')));