Email, link and text protector

proven to lower incidence of spam

The Email, Link and Text Protector encodes any text into entity syntax. The output is meant to be used in a web page, in order to make it more difficult for spam-harvesting spiders to extract the original content. The encoder was originally designed to be used on email addresses. It is not impossible to harvest emails encoded with this method - just slightly more difficult.

The principle is simple. Characters are encoded using the entity syntax &#xxx; where xxx is the numeric ASCII value for a character. For example abc would encode to a b c. You can find more information about character encoding at w3.org.

This script will do the same thing as the email encoder (which I discovered through Jim Kent's wife's, Heidi, web site). The email protector here has these additional enhancements.

• we (umm, I mean I) will never share, give out, or sell your email address to anyone,
• you can adjust the hide ratio - the fraction of characters in your text that are encoded,
• the base used for encoding is can be randomly varied, switching between decimal and hexadecimal encoding (e.g. "a" can be a or a),
• the padding length of the encoding can be randomized for each character (e.g. A, A, A), and finally

By using a hide ratio less than 1, some characters are left unencoded. This results in a partially encoded text which may foil harvesting spiders which look for text which is fully encoded. By switching the encoding between hex and dec for each token it is possible to make parsing more difficult.

Encode Text

Encoding Results

original string
http://www.bcgsc.ca

encoded text (seen by browser)
http://www.bcgsc.ca

encoded text (used in a link)
http://www.bcgsc.ca

encoded text (raw)
http://www.bcg sc.ca

Code

Perl subroutine to encode a single character.

sub encode {
    my $token = shift;
    my $randompad = shift;
    my $randombase = shift;
    my $MAXPAD = 3;
    my $ord = ord($token);
    my $format;
    my $format_prefix = "&#";
    my $format_digit  = "%d";
    my $format_suffix = ";";
    # random padding
    if ($randompad) {
	my $thispad = int(rand($MAXPAD));
	$format_digit = sprintf("%%0%dd",3+$thispad) if $thispad;
    }
    # switch base
    if ($randombase && rand() < 0.5) {
	# we want hex encoding now
	$format_digit =~ s/d/x/;
	$format_prefix = "&#X";
    }
    $format = sprintf("%s%s%s",$format_prefix,$format_digit,$format_suffix);
    return sprintf($format,$ord);
}