E-mail anti-spam protection using Javascript/PHP obfuscation.

EmailObfuscator.php

<?php
class EmailObfuscator
{
	public static function embedJavascript($x, $justPlainText = false)
	{
		$seed = mt_rand(0, 10000);
		$x = str_split($x);

		//permutation
		$a = 0;
		$b = 1;
		for ($i = 0; $i < count($x); $i ++)
		{
			$c = $a + $b;
			$a = $b;
			$b = $c;
			$j = ($seed + $a) % count($x);
			list($x[$i], $x[$j]) = [$x[$j], $x[$i]];
		}

		//substitution
		for ($i = 0; $i < count($x); $i ++)
			$x[$i] = ord($x[$i]) ^ (($seed + $i) & 0xff);

		$x = base64_encode(join('', array_map('chr', $x)));
		$id = 'm' . substr(md5(microtime(true)), 0, 8);

		$html = '<span class="mail" id="' . $id . '"></span>';
		$html .= '<script type="text/javascript">';
		$html .= 'var seed=' . $seed . ',x=window.atob(\'' . $x . '\'),y=Array(l=x.length),s=Math.sqrt(5),i;';
		$html .= 'for(i=l;i;)y[--i]=String.fromCharCode(x.charCodeAt(i)^(seed+i)&255);';
		$html .= 'for(i=l;i;)';
		$html .= 'x=Math.round(Math.pow((1+s)/2,i)/s+l+seed)%l,';
		$html .= 'y[--i]=[y[x],y[x]=y[i]][0];';

		if ($justPlainText)
			$html .= 'document.getElementById(\'' . $id . '\').innerHTML=y.join(\'\');';
		else
			$html .= 'document.getElementById(\'' . $id . '\').innerHTML=\'<a href="mailto:\'+(y=y.join(\'\'))+\'">\'+y+\'</a>\';';

		$html .= '</script>';

		$html .= '<noscript class="mail">';
		$html .= 'need JS to decode e-mail';
		$html .= '</noscript>';

		return $html;
	}
}