Admin at 20:54, 4 February 2011

2011-02-04T20:54:53Z

Admin at 22:15, 7 October 2009

2009-10-07T22:15:39Z

Admin at 19:56, 16 September 2009

2009-09-16T19:56:10Z

Admin: Created page with ''''Email Obfuscation''' or '''Email Hiding''' is an attempt to hide a valid email address on a web page from being scraped to avoid receiving spam. ...'

2009-05-14T22:26:08Z

Created page with ''''Email Obfuscation''' or '''Email Hiding''' is an attempt to hide a valid email address on a web page from being scraped to avoid receiving spam. ...'

New page

'''Email Obfuscation''' or '''Email Hiding''' is an attempt to hide a valid [[email address]] on a [[web page]] from being [[Web scraping|scraped]] to avoid receiving [[spam]].

'''Email Obfuscation''' differs from [[email encryption]] in that ''obfuscation'' conceals the actual email address from [[web scraping]], while [[email encryption]] conceals the contents of an email message in transit.

'''Email Obfuscation''' falls into a few categories:
* '''Image:''' Emails are embedded in an image which may be manipulated to prevent [[OCR]]
* '''Encoded:''' Emails are encoded using [[JavaScript]] and displayed using some form of [[encryption]]
* '''Puzzle:''' Emails are written using a simple "trick" given as textual instructions, such as "remove NOSPAM"
* '''Complete:''' Emails are not accessible without submitting a form, or completing a [[CAPTCHA]]

All of the above methods are used instead of the internet standard '''<nowiki>mailto:</nowiki>''' URL scheme which is used in a link tag in HTML:
<pre>
<a href="mailto:support@example.com">Contact Support</a>
</pre>

==Plain Email==
To fully understand how email obfuscation works, the following [[HTML]]:
<pre>
<a href="mailto:support@example.com">Contact Support</a>
</pre>
... will be obfuscated using the techniques shown above.

==Image Email Obfuscation==
A simple method of communicating an email address to a person is via an image which contains rasterized text of the email address. The web page visitor then needs to type the text directly into their email program in order to send a mail to the email address.

Similarly, [[Adobe]] [[Flash]] can be used to display an email address.

===Advantages===
* Typically easy to implement using server-based image manipulation software such as [[ImageMagick]] or [[GD Graphics Library]].

===Disadvantages===
* Site visitor copying the email address by sight is error prone
* [[OCR]] technologies are sufficiently advanced to make it easy to determine the email address by automatic methods
* [[Copy and Paste]] do not work with Image Email Obfuscation

==Encoded Email Obfuscation==
This method uses [[Character encodings in HTML]], or [[JavaScript]] to hide or otherwise obscure an email address. A simple technique is to simply use [[HTML Entities]] to encode the email address:
<pre>
<a href="&#109;a&#105;l&#116;&#111;:&#115;&#105;&#109;&#112;&#108;&#101;&#64;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#99;&#111;&#109;">Contact Support</a>
</pre>
Alternate methods use JavaScript to generate the email address using a simple form of encryption.
<pre>
<script type="text/javascript">
var e = unescape("Af%25mwjkB%27rfnqyt%3FxzuutwyEj%7Dfruqj3htr%27CHtsyfhy%25XzuutwyA4fC");
var i,p='';for(i=0;i<e.length;i++){p+=String.fromCharCode(((e.charCodeAt(i)-37)%240)+32);}
document.write(p);
</script></pre>
The above code will generate a tag identical to the plain email.
===Advantages===
* Wide variety of tools to enable encoding to be done automatically on the server.
* Behaves identically to standard email links

===Disadvantages===
* Character encoded email is easy to decrypt
* JavaScript encoded email does not operate correctly without JavaScript enabled in the visitor's [[web browser]]

==Puzzle Email==
A puzzle email is a primitive form of [[CAPTCHA]] which requires the user to solve a simple puzzle to determine the email address:
<pre>
<a href="mailto:supNOSPAMport@exaNOSPAMmple.com">Contact Support</a> (Remove NOSPAM)
</pre>
Another example:
<pre>
Contact Support: support -at- example -dot- com
</pre>
Simply enough, a site visitor needs to read the additional text and perform some simple manipulation or substitution to determine the actual email address.

===Advantages===
* Very easy to implement with little technology
* Usable on public sites
===Disadvantages===
* May be difficult to do for some users
* Errors may occur in copying email address

==Complete Email Obfuscation==
This method involves programming in a [[web server]] [[scripting language]]. The process is:
* An email address is displayed as a link in an incomplete form, such as: '''support@...'''
* Visitor clicks the link and visits a page which collects message information (From, Subject, Body) and may require the visitor to complete a [[CAPTCHA]]
* Upon successfully filling out the form, the [[web server]] sends the email on behalf of the site visitor
===Advantages===
* Email addresses are protected completely
===Disadvantages===
* Additional steps make make visitors use it less
* More complex implementation than other methods
* May be subject to [[code injection]] attacks on a web server if server-side code is not properly secured.

==See also==
* [http://www.addresslock.com/ Address Lock - A tool to encrypt using JavaScript]
* [http://www.csarven.ca/hiding-email-addresses Hiding email addresses from page source]
* [http://javascript.about.com/library/blemail1.htm Hiding Your Email Address] on About.com

[[Category:Email]]
[[Category:Web development]]

@@ Line 24: / Line 24: @@
 A simple method of communicating an email address to a person is via an image which contains rasterized text of the email address. The web page visitor then needs to type the text directly into their email program in order to send a mail to the email address.
-Similarly, [[Adobe]] [[Flash]] can be used to display an email address.
+Similarly, [[Adobe Flash]] can be used to display an email address.
 ===Advantages===

@@ Line 90: / Line 90: @@
 * [http://javascript.about.com/library/blemail1.htm Hiding Your Email Address] on About.com
-[[Category:Email]]
+[[Category:Technical]]
 [[Category:Web development]]

@@ Line 86: / Line 86: @@
 ==See also==
-* [http://www.addresslock.com/ Address Lock - A tool to encrypt using JavaScript]
+* [http://www.addresslock.com/ Address Lock - A free tool to encrypt emails using JavaScript]
 * [http://www.csarven.ca/hiding-email-addresses Hiding email addresses from page source]
 * [http://javascript.about.com/library/blemail1.htm Hiding Your Email Address] on About.com

Email address obfuscation - Revision history

Admin at 20:54, 4 February 2011

Admin at 22:15, 7 October 2009

Admin at 19:56, 16 September 2009

Admin: Created page with ''''Email Obfuscation''' or '''Email Hiding''' is an attempt to hide a valid email address on a web page from being scraped to avoid receiving spam. ...'