title: Numbers in initialization vector (IV) are all zeros
body: <p>I'm having trouble understanding the following sentence : "the numbers in initialization vector (IV) are all zeros (not the ASCII character '0').</p>
  
  <p>My goal is to use openssl enc command to encrypt a file using aes-128-cbc with a key K (let's say 1234567890) and the iv that fulfil such requirements.</p>
  
  <p>So far, I've tried not putting -iv option but it then says "iv undefined" because if option -K is used, option -iv must be provided. I've tried to used <em>-iv 0</em> but I'me not sure it is the correct one.</p>
  
  <p>For the instance, I used: </p>
  
  <pre><code>openssl enc -aes-128-cbc -e -in input.txt -out output.txt -K 1234567890 -iv 0
  </code></pre>
  
  <p>Can please you help me illustrate the correct iv that fulfill the above requirements?</p>