title: Padding the message in SHA256
body: <p>I am trying to understand SHA256. On the <a href="http://en.wikipedia.org/wiki/SHA-2#Pseudocode" rel="nofollow">Wikipedia page</a> it says:</p>
  
  <blockquote>
    <p>append the bit '1' to the message </p>
    
    <p>append k bits '0', where k is the minimum number >= 0 such that the resulting message
        length (modulo 512 in bits) is 448. </p>
    
    <p>append length of message (without the '1' bit or padding), in bits, as 64-bit big-endian
    integer
        (this will make the entire post-processed length a multiple of 512 bits)</p>
  </blockquote>
  
  <p>So if my message is <code>01100001 01100010 01100011</code> I would first add a <code>1</code> to get</p>
  
  <p><code>01100001 01100010 01100011 1</code> </p>
  
  <p>Then you would fill in <code>0</code>s so that the total length is 448 mod 512:</p>
  
  <p><code>01100001 01100010 01100011 10000000 0000 ... 0000</code> </p>
  
  <p>(So in this example, one would add 448 - 25 <code>0</code>s)</p>
  
  <p>My question is: What does the last part mean? I would like to see an example.</p>