title: Block Cipher output length puzzle
body: <p>My questions is - how the length of output ciphertext be determined?</p>
  
  <p>I vaguely know that the output length must be a multiple of block size of the cipher being used. But does that mean:</p>
  
  <ol>
  <li>If the length of input data is a multiple of cipher block size, then the output length will be the same as the input length?</li>
  <li>If the length of input data is not a multiple of cipher block size, then the output length will be the input length + one block size?</li>
  </ol>
  
  <p>Thanks!</p>