title: /dev/random permission denied
body: <p>I was reading about random numbers and their generation. I was interested in randomness since I started programming. I read that Linux Kernels also use random number generating architectures. </p>
  
  <pre><code>The structure consists of a two-level cascaded sequence of pools coupled with 
  CSPRNGs.
  Each pool is a large group of bits which represents the current state of the 
  random number generator. The CSPRNGs are currently based on SHA-1, but the 
  kernel developers are considering a switch to SHA-3.
  
  The kernel RNG produces two user-space output streams. One of these goes to 
  /dev/urandom and also to the kernel itself; the latter is useful because there 
  are uses for random numbers within the kernel. The other output stream goes to
  /dev/random. The difference between the two is that /dev/random tries to estimate
  how much entropy is coming into the system, and will throttle its output if there 
  is insufficient entropy. By contrast, the /dev/urandom stream does not throttle
  output, and if users consume all of the available entropy, the interface degrades
  to a pure CSPRNG.
  </code></pre>
  
  <p>So, full with excitement I tried to enter and check whats there in the /dev/random and /dev/urandom. But it said, </p>
  
  <pre><code>root@ubuntu:/home/sunny# /dev/random
  bash: /dev/random: Permission denied
  
  root@ubuntu:/home/sunny# /dev/urandom
  bash: /dev/urandom: Permission denied
  </code></pre>
  
  <p>However, when I check with "ls" command, I can see "random" there in /dev.
  I would like to know this in detail.</p>