title: Decrypt p7s file on iOS
body: <p>Working on a test <code>iOS</code> app I have faced the following problem.</p>
  
  <p>From a remote webserver I recieve a <code>.p7s</code> file with the following contents (which are viewable in Mac's <code>TextEdit</code> app):</p>
  
  <pre><code>0Ä  *ÜHÜ˜
  †Ä0Ä10  +�0Ä    *ÜHÜ˜
  †Ä$ÄÇ˚&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
  &lt;plist version="1.0"&gt;
  &lt;dict&gt;
      &lt;key&gt;CHALLENGE&lt;/key&gt;
      &lt;string&gt;panacya&lt;/string&gt;
      &lt;key&gt;IMEI&lt;/key&gt;
      &lt;string&gt;01 232700 828513 5&lt;/string&gt;
      &lt;key&gt;PRODUCT&lt;/key&gt;
      &lt;string&gt;iPad1,1&lt;/string&gt;
      &lt;key&gt;SERIAL&lt;/key&gt;
      &lt;string&gt;GB0269NJETU&lt;/string&gt;
      &lt;key&gt;UDID&lt;/key&gt;
      &lt;string&gt;2866681d94ae6c56d189485d39c54eaedecf211c&lt;/string&gt;
      &lt;key&gt;VERSION&lt;/key&gt;
      &lt;string&gt;9A5288d&lt;/string&gt;
  &lt;/dict&gt;
  &lt;/plist&gt;
  ������†Ç
  [0ÇÛ0Ç\†
  u6ÜΩ~60
      *ÜHÜ˜
  �0Z10   UUS10U
  
  Apple Inc.10UApple iPhone10UApple iPhone Device CA0
  110808222517Z
  140808222517Z0ÅÉ1-0+U$2890C19C-43F9-47C5-8534-A54F184E37DC10    UUS10   UCA10U  Cupertino10U
  </code></pre>
  
  <p>Here's the link to the original file - <a href="https://www.dropbox.com/s/lm05gg866zdrz20/ota-response.p7s?dl=0" rel="nofollow">https://www.dropbox.com/s/lm05gg866zdrz20/ota-response.p7s?dl=0</a></p>
  
  <p>I then save the <code>NSData</code> as a <code>.p7s</code> file to disk.</p>
  
  <p>I need to get the embedded <code>.plist</code> out of the file (judging from what I see it contains exactly that) or at least convert it to readable <code>NSString</code> which I can then display in <code>UILabel</code>.</p>
  
  <p>Is it at all possible and how do I achieve it?</p>