title: What is sha-256 padding?
body: <p>Studying a source code of one of the cpu miners I found this piece of code:</p>
  
  <pre><code>work-&gt;data[20] = 0x80000000;
  </code></pre>
  
  <p>Well, I asked the coded about it and his answer was:</p>
  
  <p><em>"Those values are part of standard SHA-2 padding"</em> </p>
  
  <p>Googling "sha 2 padding" didn't help. Can you tell me what is this for?</p>
  
  <p>I thought that <strong>md5/sha256</strong> functions simply take data and return hash. </p>
  
  <p>I don't understand the "padding" concept.</p>