Jason Hendriks

nicholaswilson

Hiding email addresses from spammers has a long history. There are some obvious golden goals, like making the process seamless to your visitors, and be practicable to implement. The one that often gets left out is accessibility, but in some areas this is actually a legal requirement.[1]
<h4>The method</h4>
To my knowledge, this plugin implements the best method so far devised. Credit goes to Roel Van Gils for this technique, which he calls Graceful Email Obfuscation.[2] The basic idea is actually very simple: use PHP and JS to hide the address effectively, and make sure the fallback can be used easily by blind or visually impaired users by using a text-based CAPTCHA.
The PHP code takes passed-in emails and generates simply-encoded string using alphabetic characters. It is therefore very hard to imagine what sort of spammer’s parser could possibly detect it. The only way is to load the whole DOM and jQuery to run the decryption routine. As far as we know, no bots go to those lengths, but it adds essentially no overhead if the theme or any other plugins already load jQuery; otherwise a fraction of a second might be added to page load.
<h4>Comparisons with other plugins</h4>
Amazingly, no other WordPress plugins seem to use this method, either offering very little spam protection, or not coping with JavaScript turned off (3-10% of users). <a href="http://www.privatedaddy.com/" rel="nofollow ugc">Private Daddy</a> comes closest, but falls at the last hurdle by offering an image CAPTCHA with no non-visual alternative. Clunky though my first code bash is, it seems to the best available at the moment if accessibility is really important to you (of course, if I did not think that, I would not have written this). There is a similar Drupal plugin.[3]
<h4>Comparisons with other methods</h4>
The most viable alternative methods are:
<ol>
<li>Using images (cf. <a href="http://www.facebook.com/" title="Facebook" rel="nofollow ugc">Visagefolio</a>). This requires typing and is a pain for everyone.</li>
<li>Poor “test [at] example [dot] com” style text replacements provide no protection and annoy users.</li>
<li>Clever things like outputting “moc.elpmaxe@tset” and using CSS unicode rules to reverse it. Unfortunately these cause trouble for the blind and in some browsers make it confusing to copy and paste the link.</li>
<li>Using XML comments or CSS <code>display: none;</code> to remove elements inside the link text. There is still no clickable link, which makes it hard for the blind to use.</li>
</ol>
<h4>JavaScript fallback</h4>
If there is no JavaScript, the user is taken to a page on the site using an empty content box where they are asked a simple text question to check whether they are a human. Basic sums are asked at the moment, though a wider range of questions could be added using the <a href="http://testCAPTCHA.com" rel="nofollow ugc">testCAPTCHA.com</a> service.
<h4>References</h4>
<ol>
<li>See particularly ‘508’ legislation in America.</li>
<li>Original description on <a href="http://www.alistapart.com/articles/gracefulemailobfuscation" title="A List Apart: Graceful Email Obfuscation" rel="nofollow ugc">A List Apart</a>.</li>
<li><a href="http://drupal.org/project/geo_filter" rel="nofollow ugc">Drupal plugin</a></li>
</ol>
Further reading:
<ol>
<li><a href="http://technology.kencarlson.org/general/graceful-e-mail-obfuscation/" rel="nofollow ugc">GEO review</a> by Ken Carlson</li>
<li>Spam obfuscation comparison recommending use of this method for 508 compliance: <a href="http://doteduguru.com/id415-e-mail-obfuscation.html" rel="nofollow ugc">.eduGuru article</a> by Michael Fienen</li>
</ol>
Some notes and future details on <a href="http://www.nicholaswilson.me.uk/2010/04/notes-on-good-email-obfuscation/" rel="nofollow ugc">my site</a>

Graceful Email Obfuscation

Hiding email addresses from spammers has a long history. There are some obvious golden goals, like making the process seamless to your visitors, and b …

bobbingwide

vsgloik

Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. 
The rset can be a toatl mses and you can sitll raed it wouthit porbelm. 
Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef but the wrod as a wlohe.
This plugin implements a version of an algorithm that will produce text similar to the above. 
Basically it changes each word by randomising the order of the letters, leaving the first and last letter of each word the same.
You implement this on your website using the [bbboing] shortcode.
The syntax is:
[bbboing 
 text=”seed|text – some text to obfuscate” 
 form=”N|Y – display form to allow changes” 
 both=”N|Y – display both original and output text”]
If you don’t specify any parameters you get a ‘bbboing’ed version of the original text.
Examples: 
 [bbboing text=”code is poetry”] may produce ‘code is peroty’ or ‘cdoe is pretoy’ 
 [bbboing text=’powered by WordPress’] may produce ‘prweoed by WrdsorPes’
It’s also feasible that the randomisation produces exactly the same output as input. 
So [bbboing text=’bobbing wide’] may produce ‘bobbing wide’
Of course, nothing happens for words with fewer than 4 letters so 
[bbboing text=’it is not a con’] WILL produce the same output as input.
You may notice that some spammers/spambots intentionally misspell words when creating comments. 
bbboing does not in anyway endorse this.
Please use bbboing for your own amusement.
Note: the bbboing plugin is dependent upon the oik plugin.

bbboing

obfuscate text but leave it readable, apparently

Graceful Email Obfuscation vs bbboing