CAPTCHA (Chilean-Argentinian-Peruvian Tango/Cha-Cha) is one of the widespread hazing rituals of the World Wide Web. It was named that way because it takes two people to tango and a week-long summit of three nations to decide that nothing can be done. (Any nations will do; the original inventor merely wanted to illustrate a point and had nothing against South Americans or Cubans.)
CAPTCHAs operate by generating an image that has text - or a sound file with speech. The picture, or sound, is distorted so that computers cannot make sense of the picture, but humans can. Usually. Sometimes the situation is the other way around.
A real-life equivalent of CAPTCHAs would be the drunk guy at the door who lets people into an exclusive party. For newcomers, he poses some weird but relatively simple questions, like he wasn't really hired to keep people out, or whatever. He also needs to ask the same questions from those people who got chucked out of the window during the party, which makes the situation harder - the people who got chucked out are probably pretty drunk already.
CAPTCHAs work the similar way to keep spambots off the web sites. They ask people annoying questions. While this frequently confuses many a stupid spambot, it does, indeed, confound many human visitors. Actually, you can confound many human visitors by simply adding a checkbox that says "are you a human? If so, check this box", because many question their humanity or have been denied the power to state that fact by the Court. The original designers of the CAPTCHA system now recommend a radio button in these situations: Yes, No, and I'm Classified As A Meat Popsicle.
Typical CAPTCHA questions
- Is this blurred, distorted text in Arial or Helvetica? I'll skewer you with a spear if you answer wrong, buddy.
- Is this an audio sample of our speech synthesis program, or one of our Evil Robotic Overlords?
- Aaaaare youuuu a Gerrrrman spyyyyy?
- Given relation ORDER(ID, DATE, PARTNAME, PRICE, QUANTITY, PARTID, USERID, FIRSTNAME, LASTNAME, ADDRESS, ZIPCODE, CITY, MINUTESOFIDLECHITCHATWHILEORDERING), please normalise it so that it satisfies 3NF. For extra points, explain which attributes you feel should also be included in a typical usage scenario. Include at least one attribute, storage of which is covered by some legislation, and explain the legal repercussions of handling such data from system engineering point of view. For even more extra points, provide a rationale for inclusion of "minutes of idle chitchat while ordering" in a database of orders.
- Here's a cat. Is it smiling? Please cite which Wikipedia editors expressed their opinion that the cat in question is or is not smiling. (Also known as a CATPTCHA or KATCHA or whatever.)
- You would like to learn more?
- "Uwe Boll punned me in the face." Is this statement supposed to be funny? And if not, why?
- Is this image appearing on a pornography site? If so, you are answering to this CAPTCHA question on a wrong website, and answering to this challenge correctly may help the Terrorists. For God's sake, give a wrong answer! The Agency appreciates your cooperation.
- Who was the 26th President of the United States? (You have to answer this answer only kind of correctly, e.g. "Teddy Roosevelt". If you answer absolutely correctly, you will be immediately deported to Gitmo. Only obvious spies bother to memorize these perfectly.)
For now, CAPTCHAs usually operate on visual and auditory senses. In the Future, when computers are undoubtedly more advanced, we can also operate on touch and taste. In the coming millennia, we may even operate on spatial senses. Example questions to be processed in the future:
- Please hold your joystick for the following test. ...No, not that joystick. The other one. Please press button 1 when ready. Does this recoil feel like a H&K MP5, FA-MAS or an AK-47?
- (Modification of the above, spotted on Universal Peace Movement web site) ...How many innocent civilians died?
- Please fasten your seatbelt and press the start button on your chair to simulate movement. [...] Was this manoeuver a split-S or an Immelmann? How many Gs do you think were simulated here?
- (Modification of the above, spotted on Aviatophobics Anonymous web site) ...feeling better now?
- [Taste CAPTCHA example censored by French authorities] (damn, we knew we shouldn't have let Brits do the pioneer work here)
CAPTCHAspotting is one of the famous Interweb Sports, and is planned to be an event in 2012 Summer Olympics. The sportsmen wander around the web and spot various sorts of CAPTCHAs, then rate them according to the unreadability, incomprehensibility, clashiness of the colours, amount of malfunctions in processing the correct answer. Extra points are given if the CAPTCHA rates highly on any of those and is also easy for computers to break.
In the Battle of the Champignons of 2007 Istanbul CAPTCHAspotting Showdown, Hans Überflügel of Stuttgart, Germany won the coveted "Golden I-Can't-Log-On-Even-If-I-Know-How Lemon of Excellence" for spotting 289 completely incomprehensible CAPTCHA-enabled login pages in less than 15 minutes. The competition was particularly tough that year.
CAPTCHA 2.0 (Captchr) is the Web 2.0 version of CAPTCHA. Web 2.0 encourages open sharing of information and makes adding information to websites as easy as possible - creation of user accounts shouldn't even be necessary and things like OpenID make life even easier.
CAPTCHA 2.0 is designed to make all that stuff as SECURE as possible. For example, when making an edit to a wiki, you need to log in though an SSL server, provide biometric credentials, and know the capital of Assyria. The major difference from CAPTCHA 1.0 is that it has rounded corners, pastel shades, glossy highlights and the the word "beta" in an actually working product.
Critics argue that merely using CAPTCHAs and Web 2.0 in a humour page makes the entire page seem predictable, drab, humourless and completely unfunny. (The readers are advised to add actually funny humour below.)