Captcha

There are few things in the world that I hate too much. One such thing is to prove a stupid computer that I am really a human , not a bot. The way we have to prove it, is so much annoying. Most of the time we have to read some distorted letters and enter them to a text box. This text is called a "CAPTCHA". "CAPTCHA" stands for "Completely Automated Public Turing test to tell Computers and Human Apart". This is a kind of Turing test. Instead of administrated by a human and targeted at a machine "Captcha" is administrated by a machine and targeted for a human. The "Captcha"s are used for variety of purposes. The main purpose is to stop spams and automated votes in voting systems. Most of the time we encounter these while registering to a website or posting a comment on a blog post. Also sometimes we have to fill a "Captcha" if we incorrectly entered a password several times.  

But I feel this has become a very annoying thing to most people. Some of the "Captcha"s are really unreadable. It is interesting to know whether there are any data available on the time that is wasted due to these "Captchas". Thus the balance between the security and the user friendliness should be maintained by carefully selecting when to use "Captcha"s and their hardness to solve .

Will the World end on 2012 ? what about 2038 ?

"The end of the world on December 2012" , probably the most feared and widely discussed thing these days. This has been probably aggravated by the recent natural disasters faced by the world such as hurricane Sandy. Though there are no scientific evidence to suggest the end of the world on 2012 most of the people reluctant to accept it as just a myth.

They claim the Maya calender ends on December 21st 2012. So whats the big deal ? Calenders do need to have an end. In fact every thing do need to have a beginning and an end. The Maya calendar starts from 3114 BC . Does that mean that the world started or began on 3114 BC ? not really. The years 3114 BC and 2012 were the years where Mayans had to remove their old calenders and get a new calender. Just as we change our calenders on January 1st. The only difference is Mayan calender was so huge and one calender was enough for massive number of generations (Calender making would not have been a prosperous business in Mayan culture).  They may have further extend their calender if they had more space and time to write the calender.


Similar problems of running out of space for keeping the time occurs even in the modern world. The Year 2038 problem is one example. This will occur on January 19th 2038.The reason is that we use 32 bit integers to represent the date objects in computers and digital systems. In these systems the date is represented as the number of seconds since January 1st 1970. The maximum integer that can be represented  by 32 bit representation is 2147483647. This is the number of seconds up to January 19th 2038. So effectively our digital calenders ends on 2038. So will the world end on January 19th 2038 ? May be in the future when a more civilized and developed society finds about this conflict, they may fear that the world ends on that day. 

Although this 19th January 2038 does not physically end the world, many problems will arise in digital systems. Almost all the systems now been used would not be able to perform date calculations. The day will be reset to Friday 13th December 1901 after 2038 causing many problems. The solution is to increase the number of bits used to represent a date in digital systems. But this will introduce backward compatible problems with current software architectures. So still a universal solution have not been found. But probably in the near future people with come up with many plausible solutions and there is no need to fear about the end of the world, unless we dig our own grave due to wars and environment pollution.

http://en.wikipedia.org/wiki/Year_2038_problem

A Great Place for Free Online Learning - Coursera

Coursera is a great place for online learning. This has subjects varying from Computer Science to History , Sociology, Medicine and Music. All the subjects are offered from the top ranked Universities in the world. Currently there are 16 Universities affiliated with Coursera and this includes MIT, CIT , Stanford University and Princeton University.

Some available courses 

The courses offered are well organized. Around 5-12 hours per week are required to complete a course and the duration of the course will be 6-16 weeks. Almost all the courses includes weekly lectures which have a duration of around 10-20 minutes. There will be several lectures per week adding up to 2 hours per week. Also there may be weekly quizzes, assignments or programming assignment depending on the course. Quizzes will either MCQ or short answers which will be evaluated automatically. Assignments are normally peer reviewed. Also most of the courses have an end exam and mid exams.After the completion of the course participants will receive a certificate if they have performed well in exams and assignments. But this certificate will not be considered as an official certificate offered by the relevant University.

Coursera is started by Andrew Ng, an Associate Professor in the Department of Computer Science at Stanford University, and Director of the Stanford Artificial Intelligence Lab and Daphne Koller a Professor in the Department of Computer Science at Stanford University . Although this was started in this year it has many partners. Currently all the courses are free and the business model is not finalized. It is expected that it will be something about selling the information about participants to potential employees and offering of certificates.

Currently Coursera offers more than 100 different subjects. The number of enrollments per subject some times exceeds 100k. These courses will give a very good chance to learn some thing new in a very organized manner. The quality of the courses are very high and it is very good chance to experience the future of e-learning. This will be a very good opportunity to gather international quality knowledge freely.Visit the Coursera web site from the following link.


https://www.coursera.org/

Some Chuck Norris Facts- Explains Many Things

• Chuck Norris' tears cure cancer. Too bad he has never cried. 
• Chuck Norris has already been to Mars; that's why there are no signs of life there. 
• The Great Wall of China was originally created to keep Chuck Norris out. It failed miserably. 
• When Alexander Bell invented the telephone he had 3 missed calls from Chuck Norris 
• Chuck Norris counted to infinity - twice. 
• Chuck Norris wakes up his alarm clock 
• Chuck Norris doesn't call the wrong number. You answer the wrong phone. 
• There used to be a street named after Chuck Norris, but it was changed because nobody crosses Chuck Norris and lives. 
• Some magicians can walk on water, Chuck Norris can swim through land. 
• Chuck Norris remembers the future. 
• Chuck Norris and Superman once fought each other on a bet. The loser had to start wearing his underwear on the outside of his pants. 
• Chuck Norris will never have a heart attack. His heart isn't nearly foolish enough to attack him. 
• Chuck Norris received his pilots license by just looking at an airplane. 
• Chuck Norris does not hunt because the word hunting infers the probability of failure. Chuck Norris goes killing. 
• Chuck Norris called 911 to order Chinese food and got it. 
• Only Chuck Norris can dislike on Facebook 
• Chuck Norris uses a sundial at night. 
• When Chuck Norris looks at himself at a mirror, there is no reflection. There can only be one Chuck Norris. 
• Contrary to popular belief, Chuck Norris cannot fly. He just jumps and chooses when to come down. 

How Secured is Your Security Question ????

You may have seen different kinds of questions such as "What is your library card no ?" , "what is your mothers birth town ?", while registering for an online account.These questions are used in password recovery processes and additional sign in verifications. Normally we all care about our passwords and worry about the security of the password.

But do we really care about these security questions ? It seems most of us don't care much about these.Most of the time we give our real details as the answers to theses questions and simply forget about the security question.Even I was unaware of security questions selected for my email address until i decided to write this post.The most surprising thing is that I can't come up with the correct answer for those questions.I think this is common between most of us.We really DON'T CARE about those.

But in reality this is a great security risk.Even if you have a very good password that can not be guessed easily,you may be vulnerable to security threats.It is like locking the front door while leaving the backdoor open.The confidentiality of the answers for a security question will be far less than a password.If some one asks you a password you probably wont tell.But if some one asks you the birth town of your mother you may answer it.Also most of the details that are asked in security questions can be found publicly or can easily be guessed.That is what happened with the email account of Sarah Palin the vice president candidate during 2008 elections.

A good security question should have a answer which can be easily memorized, which is not publicly available and which does not change overtime. Further the possible number of answers for the question should be very large so that it can not be guessed. There are some websites which offers good security questions. But it is worth to note that the goodness of the question depends on the expected answer as well.