186 Let us look at another example which will help with

   186 Let us look at another example which will help with understanding how

   187 understanding how passwords should be verified and stored.

   187 passwords should be verified and stored.  Imagine you need to develop

   188 Imagine you need to develop a web-application that has the

   188 a web-application that has the feature of recording how many times a

   189 feature of recording how many times a customer visits a page.

   189 customer visits a page.  For example in order to give a discount

   190 For example in order to give a discount whenever the customer

   190 whenever the customer has visited a webpage some $x$ number of times

   191 has visited a webpage some $x$ number of times (say $x$ equal

   191 (say $x$ equal $5$). There is one more constraint: we want to store

   192 $5$). There is one more constraint: we want to store the

   192 the information about the number of visits as a cookie on the

   193 information about the number of visits as a cookie on the

   193 browser. I think, for a number of years the webpage of the New York

   194 browser. I think, for a number of years the webpage of the New

   194 Times operated in this way: it allowed you to read ten articles per

   195 York Times operated in this way: it allowed you to read ten

   195 month for free; if you wanted to read more, you had to pay. My best

   196 articles per month for free; if you wanted to read more, you

   196 guess is that it used cookies for recording how many times their pages

   197 had to pay. My best guess is that it used cookies for

   197 was visited, because if I switched browsers I could easily circumvent

   198 recording how many times their pages was visited, because if I

   198 the restriction about ten articles.\footnote{Another online media that

   199 switched browsers I could easily circumvent the restriction

   199   works in this way is the Times Higher Education

   200 about ten articles.

   200   \url{http://www.timeshighereducation.co.uk}. It also uses cookies to

   201 restrict the number of free articles to five.}