Efficient Captchas

There is a whole lot of buzz in the internet about alternatives to captchas (i mean alternatives to image captchas). Its not mainly because captchas are not secure against bots, but because they aren't convenient!!!
People are getting bugged because of highly illegible captcha strings (http://tinyurl.com/5bvk7c).

But i really feel, captchas, if done properly are the best form of human recognition technique. Its simple, fast, and sufficiently secure. People are used to image captchas, and it just works! I get more bugged when I'm asked silly questions, or to solve a mathematical equation or when i have to select kittens out of 9 pictures of animals!!!

I put up some points here on how to create usable and convenient captchas:

1. Use a light background. I'll prefer a plain white background. Backgrounds do provide some security but having a regular background for all captchas does not helps as an average captcha solving algo will adapt itself to it.

So, its always better to present your captcha in white background, so that its easier to read.

2. Dont just use random words, instead use a phonetic generator to generate your captcha strings. This helps a lot in terms of captcha usability. Also, a phonetic generator does not poses much threat to your captcha getting hacked. Sure, it increases the threat but it provides more usability than threat.

3. DO NOT use a straight baseline and loosely couples letters. While writing any captcha hacking program, the most difficult operation is Segmentation. You can captivate on this weakness of captcha hackers by keeping wavy baselines and keeping letters coupled in random fashion.

4. Use single color for your captcha (better user experience and readability). A captcha bot can easily convert your captcha to grayscale for hacking.

5. Use letter warping, instead of image warping for the whole captcha. Warped letters are difficult to segment and recognize.

6. Differnt length captcha strings everytime for more security.

I hope it helps the community and eventually the end users, the humans!!!

Comments

Post a Comment

Popular posts from this blog

Alarm Clock Myth - How to wake up early

Image
Everyone wants to wake up early, and make good use of those extra early morning hours. But we fail all the time, even if we succeed, its one-off times. I thought its a good opportunity to seize and fix this problem with the existing alarm clocks. I started exploring the existing solutions out there and found there are quite many interesting stuff: A whole breed of biologically sync'd clocks who wake you up when you are least in sleep Hard to snooze alarm clocks which ask you to solve a difficult puzzle to snooze an annoying alarm tone Motivational messages to wake you up I gave all the existing products a lot of thought and why they don't quite work. Here is my conclusion: People don't really understand the real purpose of alarm clocks .   Here's the deal: Alarm clocks are not meant to wake you up. Yes, you read it right. Alarm clocks really are the mission-control, last resort plan to wake you up at the deadline time. You are supposed to get up on
Read more

Intelligent Passwords

I attempt and dare to solve the problem of password-stealing which occur primarily due to Social Engineering Hacks. Also, this adds another layer of protection over passwords and make passwords more secure and usable! The method exploits the fact that given a word to type, different people will type the word in different fashions. The speed of typing will be different and the typing-accent will vary. We now attach this typing-accent attribute to the password and make them more secure i.e. even if you tell your password to a third-person, he wont be able to authenticate himself as you. Also, this improves the usability of passwords. As pointed by Jakob Nielsen, un-masking the password would provide better usability. Passwords can now be unmasked as this method tries to cover for the social engineering hacks which are the clear threats to unmasking passwords. As a proof of concept, i provide a demo here . The demo is Javascript based, where you can set your password and then attempt to e
Read more

The little thing that makes me hate Android

Android is awesome. We found love in a hopeless place. It's the unix of mobile phones. But it is so fricking annoying when: It vibrates on shutdown Why? Why does it have to vibrate on shutdown?? My phone battery definitely dies everyday because battery-life sucks and I suck more since I am too lazy to keep my phone charged. Now, when battery gives up, phone shuts down silently and in the end it vibrates. I pull the phone out of my pocket to see what the vibration was about, click the Power Button and it starts booting up, just to shutdown again! You may call it a dark pattern/(insert a mumbo-jumbo here), I call it wtf. wtf.
Read more