Wednesday, June 20, 2007

jeaig (jgc's email address image generator) launches

Today is launch day for a simple little web site called jgc's email address image generator. It's a web service that enables anyone to generate a CAPTCHA like image containing their email address for insertion on their web site.

Since web crawlers are currently unable to look inside images to scrape email address this means that your email address will not be scraped from a web site, but can be written down by a human.

Here's an example email address:

Made using jeaig

and the code that generates that is:

<img src="
<br />
<font size="-2">Made using <a href="">jeaig</a></font>

The server does not store the email address: when a user enters an email address on the site it is padded with a random amount of random data (both before and after the address) with randomness being supplied by /dev/urandom. Then the address is encrypted using Blowfish using a secret key known only to the jeaig server (this key was also generated from /dev/urandom) and a random IV is chosen.

The encrypted data is then modified base-64 encoded so that it can be used in the URL.

When the image is requested using the special base-64 filename the email address is decrypted and then rendered using CAPTCHA code to produce the image. The image changes each time the email address is loaded.

And, yes, this is a free service.