My New Favourite Brainteaser

I just had my mind blown by the most diabolical brainteaser. At first glance it seems impossible to figure out, but there is actually a fairly logical way to solve it. I wish I could say that I solved it, but I have to admit to giving up.  Here it is:

Two mathematicians are at the pub having a beer and a yarn. One of them says “Hey, I bet you $5 you can’t work out the ages of my three daughters.”
The other one says “Is that so? I’ll take your bet.”
“Okay, so the product of their ages is 72. The sum of their ages is the same as the number of the house across the street.”
The second mathematician thinks about it for a moment, then says “You haven’t given me enough information to solve the riddle.”
“Okay, my eldest daughter loves chocolate.”
The second mathematician says “Too easy”, gives the answer and takes his $5.

How old are the daughters?

Is your password really secure?

Having worked in IT for many years, I thought I had a good handle on how to create a secure password. My passwords didn’t use dictionary words, I used mixed case, numbers and symbols. Of course, they were damn difficult to remember, so I ended up using words and substituting numbers and symbols into them.

Well, it turns out that doing that probably made my passwords easier to crack. How could that be? Well password cracking tools are pretty sophisticated these days, and they automatically try common letter/number substitutions (like replacing an “o” with a zero). A while back I found an xkcd comic that explained exactly how easy such passwords are for computers to crack. Continue reading “Is your password really secure?”