title: Sign file with .der-Certificate and create signature (pkcs#7)
body: <p>The thing I would like to do is:</p>
  
  <ul>
  <li>Sign a zip-file with openssl using a certificate and create a signature-file (pkcs#7)</li>
  </ul>
  
  <p>What I have/I did so far:</p>
  
  <ol>
  <li>I installed openssl and opened the console</li>
  <li>I created a rsa key (openssl genrsa -out key.pem 2048)</li>
  <li>I created a request (openssl req -batch -sha256 -new -key key.pem
  -out request.pem –subj '/C=../ST=../L=../O=../OU=../CN=..')</li>
  <li>I sent this request to someone who did any magic with the request
  and sent me an file named 'certificate.der'. When I open this file there are some information like oscp-url and things like this.</li>
  </ol>
  
  <p>So far, so good. Next my naive approach is to sign the zip-file with this certificate and tell openssl to create the pkcs#7-signature so I can verify it using the ocsp-responder.
  But I have really not the foggiest notion whether the approach is correct and how to sign the zip-file. :-( If I have errors in reasoning please also let me know. :-)</p>
  
  <p>Can someone please help me?</p>