title: complexity analysis of RSA algorithm
body: <p>The security of RSA hinges upon a simple assumption:</p>
  
  <blockquote>
    <p>Given N, e, and y = (x ^e) mod N, it is computationally intractable to
    determine x.</p>
  </blockquote>
  
  <p>This assumption is quite plausible. How might Eve try to guess x?</p>
  
  <p>She could experiment with all possible values of x, each time checking whether x^e is equal to  y mod N, but this would take exponential time. Or she could try to factor N to retrieve p and q, and then figure out d by inverting e modulo (p-1)(q-1), but we believe factoring to be hard. Intractability is normally a source of dismay; the insight of RSA lies in using it to advantage.</p>
  
  <p>My question on above text </p>
  
  <ol>
  <li>How we got exponential time for calcuation for each value of x in above context?</li>
  </ol>