title: Timestamp Validation in Adobe Reader / Acrobat fails: Document was changed or damaged
body: <p>I'm currently working on a timestamp service producing PAdES-4-compliant timestamps. This is working fine with timestamps received from the Swisscom / Swisssign / QuoVadis servers. But whenever I use a timestamp received from my own timestamping authority or Signtrust, Adobe Reader (Version 11.0.06) keeps rejecting my timestamp with the German comment: "Dokument wurde nach dem Unterzeichnen verändert oder beschädigt", which means 'The document was changed or damaged after signature creation'. Adding the required certificates to the trust list (so that the tsa signer certificate validates successfully) has no impact on this behavior.</p>
  
  <p>Since the timestamps received from the TSAs mentioned above validate correctly, I assume that my basic digest calculation is just fine.</p>
  
  <p>Since my external (non-PAdES) CMS-based timestamps validate correctly with alternative signature applications, I assume the digest's encoding as well as the timestamp structure are just fine.</p>
  
  <p>With my own TSA, I use the same digest algorithms and structures as Swisssign, yet Adobe Reader just won't accept it. Since there is no further error detail given by Adobe Reader, I'm kind of lost.</p>
  
  <p>Has anyone got an idea, what is wrong with the timestamp in the document found under: <a href="https://dl.dropboxusercontent.com/u/40847151/Timestamping/TS%20-%20selfsigned.pdf" rel="nofollow">https://dl.dropboxusercontent.com/u/40847151/Timestamping/TS%20-%20selfsigned.pdf</a></p>
  
  <p>You cann find the working Swisssign test file here: <a href="https://dl.dropboxusercontent.com/u/40847151/Timestamping/TS%20-%20Swisssign.pdf" rel="nofollow">https://dl.dropboxusercontent.com/u/40847151/Timestamping/TS%20-%20Swisssign.pdf</a></p>
  
  <p>Any hint is highly appreciated!</p>
  
  <p>Regards,</p>
  
  <p>Thomas</p>