title: Understanding SSL
body: <p>I have three questions regarding SSL that I don't fully understand.</p>
  
  <ol>
  <li><p>If I get it correctly, a server <code>A</code> submits a request to a certain CA. Then, it receives (after validation etc.) a digital certificate composed of a public key + identity + an encription of this information using the CA's private key.</p>
  
  <p>Later on, a client <code>B</code> wants to open an SSL communication with <code>A</code>, so <code>A</code> sends <code>B</code> its digital certificate.</p>
  
  <p>My question is can't <code>B</code> just take this certificate, thus stealing the identity <code>A</code> - which will allow them to authenticate as <code>A</code> to <code>C</code>, for example. I understand that <code>C</code> will decrypt the certificate with the CA's public key, It will then encrypt its symetric key which will only be decryptable by the real <code>A</code>.</p>
  
  <p>However, I do not see where authentication comes to play if <code>B</code> can actually steal <code>A</code>'s identity. Unless I am missing something.</p></li>
  <li><p>Second question: Why use hashing on the certificate if a part of it is already encrypted by the CA? Doesn't this mean that no one can mess around with a digital certificate (in high probability) anyway?</p></li>
  <li><p>If I am stackoverflow and I have 3 servers doing the same thing - allowing clients to access, read, identify etc. - do I have to have a different digital certificate for each of the 3 servers.</p></li>
  </ol>
  
  <p>Thank you very much.</p>